AimThis qualitative study explores with health professionals the provision of, and challenges for... more AimThis qualitative study explores with health professionals the provision of, and challenges for, postdischarge stroke care, focussing on eating, drinking and psychological support across India.DesignQualitative semistructured interviews.SettingSeven geographically diverse hospitals taking part in a Global Health Research Programme on Improving Stroke Care in India.ParticipantsA purposive sample of healthcare professionals with current experience of working with patients who had a stroke.ResultsInterviews with 66 healthcare professionals (23 nurses (14 staff nurses; 7 senior nurse officers; 1 intensive care unit nurse; 1 palliative care nurse)); 16 doctors (10 neurologists; 6 physicians); 10 physiotherapists; 5 speech and language therapists; 4 occupational therapists; 4 dieticians; 2 psychiatrists; and 2 social workers resulted in three main themes: integrated inpatient discharge care planning processes; postdischarge patient and caregiver role and challenges; patient and caregive...
Abstract We studied the nucleation and growth of TiO2 nanoflowers and carbon nanotubes-TiO2 nanoc... more Abstract We studied the nucleation and growth of TiO2 nanoflowers and carbon nanotubes-TiO2 nanocomposite (n-CNT-TiO2) by the hydrothermal method in a single step at 150 °C and tested them for the photocatalytic degradation of MB. The microstructural analysis confirmed the transformation of TiO2 nanoflowers to CNT-TiO2 spheres due to the role of surface energy of CNT. The XRD peak profile analysis of TiO2 and n-CNT-TiO2 confirmed the formation of pure rutile phase of Titania sintered at 400 °C. A red-shift in the bandgap of n-CNT-TiO2 nanocomposite (2.7eV) was observed due to the donor states towards the conduction band edge. The core-level of XPS showed the strong interaction between carbon and titanium atoms. The CNT facilitate the interfacial charge transfer or avoid the formation of charge recombination due to the variation of Ti4+ to Ti3+ sites. The highest photocatalytic degradation was achieved by using the photocatalyst of n-CNT-TiO2 nanocomposite. The incorporation of CNT provides the interfacial charge transfer facility that creates new interbands energy states for the delay of electron-hole recombination, which cater the environmental remediation.
The hole density of individual copper sulfide nanocrystals (Cu2-xS NCs) is determined from the st... more The hole density of individual copper sulfide nanocrystals (Cu2-xS NCs) is determined from the stoichiometric mismatch (x) between copper and sulfide atoms. Consequently, the electronic properties of the material vary over a range of x. To exploit Cu2-xS NCs in devices, assemblies of NCs are typically required. Herein, we investigate the influence of x, referred to as the stoichiometric doping effect, on the structural, optical, electrical, and thermoelectric properties of electronically coupled Cu2-xS NC assemblies. The doping process is done by immersing the solid NC assemblies into a solution containing a Cu(I) complex for different durations (0-10 min). As Cu+ gradually occupied the copper-deficient sites of Cu2-xS NCs, x could be controlled from 0.9 to less than 0.1. Consequently, the near-infrared (NIR) absorbance of Cu2-xS NC assemblies changes systematically with x. With increasing x, electrical conductivity increased and the Seebeck coefficient decreased systematically, leading to the maximal thermoelectric power factor from a film of Cu2-xS NCs at an optimal doping condition yielding x = 0.1. The physical characteristics of the Cu2-xS NC assemblies investigated herein will provide guidelines for exploiting this emerging class of nanocrystal system based on doping.
The microwave hydrothermal and photo-reduction/deposition methods were employed to synthesize sil... more The microwave hydrothermal and photo-reduction/deposition methods were employed to synthesize silver nanoparticles (Ag NPs) decorated α-Nickel molybdate (α-NiMoO 4) nanorods. TEM image clearly shows the decoration of Ag NPs on α-NiMoO 4 nanorods. The Ag NPs decorated α-NiMoO 4 revealed eight folds increase in photocatalytic degradation of tetracycline (TC) compared to the α-NiMoO 4 under visible light irradiation. The photocatalyst shows excellent stability even after 5 th cycle of TC degradation as confirmed by XRD, XPS, and FESEM measurements. In addition, the photocatalyst shows anti-photo corrosion properties. TOC analysis and fluorescence spectroscopy analysis indicate the efficient degradation and mineralization of TC. The enhanced photocatalytic activities of photocatalyst could be attributed to increase in visible light absorption, SPR effect, and efficient separation of electron-hole pairs. The suppression of charge recombination confirmed by PL spectra, transient photocurrent response, EIS, and CV. ESR measurement and scavenger experiment suggest that OH • plays a major role whereas O 2 •and h + show the minor role for TC degradation. In order to find out the transformation products in water and degradation pathways of TC, UPLC-PDA and HR-QTOF ESI/MS techniques were used. The five degradation pathways are designed for TC on the basis of demethylation, hydroxylation, dehydroxylation, oxidation, and deamination organic reactions. Moreover, the ESR measurement was used to prove the photocatalytic mechanism. So, this work could provide a fabrication of efficient photocatalyst for removal of pharmaceuticals pollutants from waste water as well as deeper insight into photocatalytic mechanism, transformation products, and degradation pathways of TC in water.
Bulletin of The Korean Chemical Society, Mar 16, 2023
We report the map of 20 reactions that take place during vapor‐phase photochemical dehydrogenatio... more We report the map of 20 reactions that take place during vapor‐phase photochemical dehydrogenation of ethanol on four metal‐doped TiO2 (Mn/TiO2, Mn = nanoparticles of Pd, Pt, Au, and Cu) under solar simulated light. The reactions are sensitively affected by the moisture amount and the nature of the carrier gas. To construct the above map, we also used CH3CHO, CH3CO2H, (C2H5O)2CHCH3, and CH3CO2C2H5, respectively, as an independent starting reagent. Amazingly, Mn/TiO2 not only serves as photocatalysts but also as thermocatalysts for various reactions that appear in the above map. The reaction is proposed to proceed by a radical mechanism in which photoinduced electron transfer from the valence band to the conduction band of TiO2 is the initial step and the subsequent electron injection from organic reactants to the hole in the TiO2 valence band. This report also features highly valuable unprecedented reactions, which bear great potential to be commercialized.
We report the map of 20 reactions that take place during vapor‐phase photochemical dehydrogenatio... more We report the map of 20 reactions that take place during vapor‐phase photochemical dehydrogenation of ethanol on four metal‐doped TiO2 (Mn/TiO2, Mn = nanoparticles of Pd, Pt, Au, and Cu) under solar simulated light. The reactions are sensitively affected by the moisture amount and the nature of the carrier gas. To construct the above map, we also used CH3CHO, CH3CO2H, (C2H5O)2CHCH3, and CH3CO2C2H5, respectively, as an independent starting reagent. Amazingly, Mn/TiO2 not only serves as photocatalysts but also as thermocatalysts for various reactions that appear in the above map. The reaction is proposed to proceed by a radical mechanism in which photoinduced electron transfer from the valence band to the conduction band of TiO2 is the initial step and the subsequent electron injection from organic reactants to the hole in the TiO2 valence band. This report also features highly valuable unprecedented reactions, which bear great potential to be commercialized.
The characteristic NIR of copper sulfide nanocrystals (Cu2−xS NCs) assemblies based on the LSPR c... more The characteristic NIR of copper sulfide nanocrystals (Cu2−xS NCs) assemblies based on the LSPR can be controlled by exploiting monovalent lithium ions through electrochemical methods.
Lately, the upsurge in the liberation of synthetic dyes into the environment, primarily by the te... more Lately, the upsurge in the liberation of synthetic dyes into the environment, primarily by the textile industries, is a threat to the natural habitat and existing ecosystem. Various methods such as adsorption and degradation with nanoparticles are currently being used to degrade those hazardous materials, but still, the yearning for novel methods continues. In this study, hydrothermal reactions were performed at 160°C to synthesize manganese dioxide nanostructures (MnNSs) under different incubation periods that facilitated the comparison of the size, morphology, and crystallinity of MnNSs. The study revealed the change in crystallinity over the incubation period; MnNSs prepared at 24 hrs were highly crystalline among others. Additionally, the size and morphology of MnNSs changed from the sea-urchin or flower-like structure, predominantly sheet/layer form, to nanorods as the reaction proceeded for 24 hrs. Characterization of MnNSs was followed by heterogeneous Fenton’s reaction, usin...
The hole density of individual copper sulfide nanocrystals (Cu2-xS NCs) is determined from the st... more The hole density of individual copper sulfide nanocrystals (Cu2-xS NCs) is determined from the stoichiometric mismatch (x) between copper and sulfide atoms. Consequently, the electronic properties of the material vary over a range of x. To exploit Cu2-xS NCs in devices, assemblies of NCs are typically required. Herein, we investigate the influence of x, referred to as the stoichiometric doping effect, on the structural, optical, electrical, and thermoelectric properties of electronically coupled Cu2-xS NC assemblies. The doping process is done by immersing the solid NC assemblies into a solution containing a Cu(I) complex for different durations (0-10 min). As Cu+ gradually occupied the copper-deficient sites of Cu2-xS NCs, x could be controlled from 0.9 to less than 0.1. Consequently, the near-infrared (NIR) absorbance of Cu2-xS NC assemblies changes systematically with x. With increasing x, electrical conductivity increased and the Seebeck coefficient decreased systematically, leading to the maximal thermoelectric power factor from a film of Cu2-xS NCs at an optimal doping condition yielding x = 0.1. The physical characteristics of the Cu2-xS NC assemblies investigated herein will provide guidelines for exploiting this emerging class of nanocrystal system based on doping.
Abstract We studied the nucleation and growth of TiO2 nanoflowers and carbon nanotubes-TiO2 nanoc... more Abstract We studied the nucleation and growth of TiO2 nanoflowers and carbon nanotubes-TiO2 nanocomposite (n-CNT-TiO2) by the hydrothermal method in a single step at 150 °C and tested them for the photocatalytic degradation of MB. The microstructural analysis confirmed the transformation of TiO2 nanoflowers to CNT-TiO2 spheres due to the role of surface energy of CNT. The XRD peak profile analysis of TiO2 and n-CNT-TiO2 confirmed the formation of pure rutile phase of Titania sintered at 400 °C. A red-shift in the bandgap of n-CNT-TiO2 nanocomposite (2.7eV) was observed due to the donor states towards the conduction band edge. The core-level of XPS showed the strong interaction between carbon and titanium atoms. The CNT facilitate the interfacial charge transfer or avoid the formation of charge recombination due to the variation of Ti4+ to Ti3+ sites. The highest photocatalytic degradation was achieved by using the photocatalyst of n-CNT-TiO2 nanocomposite. The incorporation of CNT provides the interfacial charge transfer facility that creates new interbands energy states for the delay of electron-hole recombination, which cater the environmental remediation.
A novel type of adsorbent, TiO2 impregnated pomegranate peels (PP@TiO2) was successfully synthesi... more A novel type of adsorbent, TiO2 impregnated pomegranate peels (PP@TiO2) was successfully synthesized and its efficacy was investigated based on the removal of As(III) from water. The adsorbent was characterized using Scanning Electron Microscopy (SEM), Energy Dispersive X-ray Spectrometer (EDS), X-ray Diffraction (XRD) analysis, and Fourier Transform Infrared (FTIR) Spectroscopy, to evaluate its morphology, elemental analysis, crystallinity, and functional groups, respectively. Batch experiments were conducted on PP@TiO2 for As(III) adsorption to assess the adsorption isotherm, effect of pH, and adsorption kinetics. Characterization data suggested that TiO2 was successfully impregnated on the biomass substrate. The equilibrium data better fitted to the Langmuir isotherm model having a maximum adsorption capacity of 76.92 mg/g and better distribution coefficients (KD) in the order of ~103 mL/g. The highest percentage of adsorption was found at neutral pH. The adsorption kinetics foll...
Abstract We synthesized yttrium-doped CNT-ZnO (CNT-YZO) nanoparticles (NPs) and nanoflowers (NFs)... more Abstract We synthesized yttrium-doped CNT-ZnO (CNT-YZO) nanoparticles (NPs) and nanoflowers (NFs) from the hydrothermal method at 130 °C. The effect of Y3+-concentrations in nanostructured CNT-YZO was determined in terms of the photocatalytic degradation of methylene blue (MB). Microstructural analysis showed the hexagonal cubic structure of ZnO regardless of Y-concentration or the addition of CNTs during the nucleation and growth. The specific surface area, total pore volume, and mean pore diameter of typical CNT-YZO NFs were observed to be 36.109 m2/g, 0.162 cm3/g, and 17.932 nm, respectively. The photocatalytic degradation performance of CNT-YZO NFs improved due to increase reactive sites of the catalyst and reduced recombination of photo-induced carriers. The surface-area normalized first-order decomposition rates (r/m2) of CNT-YZO NFs showed the highest photocatalytic degradation (99%). The CNT-YZO has produced a new kind of material for the photocatalytic degradation under the irradiation of visible light using a solar simulator.
Zinc oxide (ZnO) nanorods incorporated activated carbon (AC) composite photocatalyst was synthesi... more Zinc oxide (ZnO) nanorods incorporated activated carbon (AC) composite photocatalyst was synthesized using a hydrothermal process. The AC was prepared from lapsi (Choerospondias axillaris) seed stone, an agricultural waste product, found in Nepal by the chemical activation method. An aqueous suspension of AC with ZnO precursor was subjected to the hydrothermal treatment at 140 °C for 2 h to decorate ZnO rods into the surface of AC. As-obtained ZnO nanorods decorated activated carbon (ZnO/AC) photocatalyst was characterized by various techniques, such as scanning electron microscopy (SEM), X-ray diffraction (XRD), and photoluminescence (PL) spectroscopy. Results showed that highly crystalline hexagonal ZnO nanorods were effectively grown on the surface of porous AC. The photocatalytic property of the as-prepared ZnO/AC composite was studied by degrading methylene blue (MB) dye under UV-light irradiation. The ZnO/AC composite showed better photocatalytic property than that of the pris...
Polymeric microspheres from polylactide and infusion of Woodfordia fruticosa flower were prepared... more Polymeric microspheres from polylactide and infusion of Woodfordia fruticosa flower were prepared using emulsion-solvent evaporation method. The obtained microspheres were spherical to oval in shape with the size ranging from 1-29.8 µM with WFPM-2 yielding the major population within a range of 1-6 µm.
Porous activated carbon (AC) and magnetic iron oxide nanoparticles (NPs) are widely used for the ... more Porous activated carbon (AC) and magnetic iron oxide nanoparticles (NPs) are widely used for the removal of arsenic from water body. Fabrication of composite material of iron oxide NPs on the surface of porous AC can further enhance this activity for commercial application. In this research, a magnetic AC composite for arsenic adsorption was prepared by facile hydrothermal treatment of aqueous solution containing activated carbon obtained from lapsi seed stone, iron(II) chloride, polyvinylpyrrolidone (PVP) and ethanol. Several analytical techniques such as scanning electron microscopy (SEM), energy dispersive x-ray (EDX), X-ray diffraction (XRD) and Fourier-transform infrared spectroscopy (FTIR) confirmed the formation of magnetite (Fe3O4) nanoparticles on the surface of porous AC. The prepared materials were accessed for their arsenic adsorption capacity using arsenic (III) trioxide solution and found that composite Fe2O3/AC can remove the arsenic from water far more effectively th...
Activated carbon is greatly used to adsorb toxic heavy metals from water bodies. Simultaneous re... more Activated carbon is greatly used to adsorb toxic heavy metals from water bodies. Simultaneous removal of such pollutants and pathogenic impurities is essential for safe drinking water. In this study, silver nanoparticles (NPs) doped activated carbon (AC) composite was fabricated via hydrothermal technique and green synthesis technique using commercial activated carbon powder and silver nitrate solution. Several analytical techniques, including scanning electron microscopy (SEM), energy dispersive x-ray (EDX), X-ray diffraction (XRD) and Fourier-transform infrared spectroscopy (FTIR) confirmed the formation of silver nanoparticles on the surface and pores of AC. The prepared composite materials were accessed for their anti-bacterial property using Escherichia coli and Staphylococcus aureus and found that such materials have good antibacterial activity which shows that as fabricated composite can be used potentially for water treatment.
Plant-mediated synthesis of silver nanoparticles through green chemistry approach has evolved int... more Plant-mediated synthesis of silver nanoparticles through green chemistry approach has evolved into a new era of research; however, the heterogeneous size and dispersity of silver nanoparticles have limited its applications, such as surface-enhanced Raman scattering, plasmon resonance, and more specifically in the medical field of target drug delivery and therapeutic activity. Here-we investigated the effect of purification and separation modes on the dispersity, size, and morphology of silver nanoparticles, synthesized by plant extract (Nyctanthes arbor-tristis). Transmission electron microscopy revealed silver nanoparticles with an average diameter of 13.0 nm when synthesized through ethanol precipitation, which is advantageously smaller. This result suggests that the silver nanoparticles size can be fine-tuned by changing the separation mode during purification from plant extract. Due to uniformity, our obtained nanoparticles can be expected to show higher catalytic activity towar...
The microwave hydrothermal and photo-reduction/deposition methods were employed to synthesize sil... more The microwave hydrothermal and photo-reduction/deposition methods were employed to synthesize silver nanoparticles (Ag NPs) decorated α-Nickel molybdate (α-NiMoO 4) nanorods. TEM image clearly shows the decoration of Ag NPs on α-NiMoO 4 nanorods. The Ag NPs decorated α-NiMoO 4 revealed eight folds increase in photocatalytic degradation of tetracycline (TC) compared to the α-NiMoO 4 under visible light irradiation. The photocatalyst shows excellent stability even after 5 th cycle of TC degradation as confirmed by XRD, XPS, and FESEM measurements. In addition, the photocatalyst shows anti-photo corrosion properties. TOC analysis and fluorescence spectroscopy analysis indicate the efficient degradation and mineralization of TC. The enhanced photocatalytic activities of photocatalyst could be attributed to increase in visible light absorption, SPR effect, and efficient separation of electron-hole pairs. The suppression of charge recombination confirmed by PL spectra, transient photocurrent response, EIS, and CV. ESR measurement and scavenger experiment suggest that OH • plays a major role whereas O 2 •and h + show the minor role for TC degradation. In order to find out the transformation products in water and degradation pathways of TC, UPLC-PDA and HR-QTOF ESI/MS techniques were used. The five degradation pathways are designed for TC on the basis of demethylation, hydroxylation, dehydroxylation, oxidation, and deamination organic reactions. Moreover, the ESR measurement was used to prove the photocatalytic mechanism. So, this work could provide a fabrication of efficient photocatalyst for removal of pharmaceuticals pollutants from waste water as well as deeper insight into photocatalytic mechanism, transformation products, and degradation pathways of TC in water.
AimThis qualitative study explores with health professionals the provision of, and challenges for... more AimThis qualitative study explores with health professionals the provision of, and challenges for, postdischarge stroke care, focussing on eating, drinking and psychological support across India.DesignQualitative semistructured interviews.SettingSeven geographically diverse hospitals taking part in a Global Health Research Programme on Improving Stroke Care in India.ParticipantsA purposive sample of healthcare professionals with current experience of working with patients who had a stroke.ResultsInterviews with 66 healthcare professionals (23 nurses (14 staff nurses; 7 senior nurse officers; 1 intensive care unit nurse; 1 palliative care nurse)); 16 doctors (10 neurologists; 6 physicians); 10 physiotherapists; 5 speech and language therapists; 4 occupational therapists; 4 dieticians; 2 psychiatrists; and 2 social workers resulted in three main themes: integrated inpatient discharge care planning processes; postdischarge patient and caregiver role and challenges; patient and caregive...
Abstract We studied the nucleation and growth of TiO2 nanoflowers and carbon nanotubes-TiO2 nanoc... more Abstract We studied the nucleation and growth of TiO2 nanoflowers and carbon nanotubes-TiO2 nanocomposite (n-CNT-TiO2) by the hydrothermal method in a single step at 150 °C and tested them for the photocatalytic degradation of MB. The microstructural analysis confirmed the transformation of TiO2 nanoflowers to CNT-TiO2 spheres due to the role of surface energy of CNT. The XRD peak profile analysis of TiO2 and n-CNT-TiO2 confirmed the formation of pure rutile phase of Titania sintered at 400 °C. A red-shift in the bandgap of n-CNT-TiO2 nanocomposite (2.7eV) was observed due to the donor states towards the conduction band edge. The core-level of XPS showed the strong interaction between carbon and titanium atoms. The CNT facilitate the interfacial charge transfer or avoid the formation of charge recombination due to the variation of Ti4+ to Ti3+ sites. The highest photocatalytic degradation was achieved by using the photocatalyst of n-CNT-TiO2 nanocomposite. The incorporation of CNT provides the interfacial charge transfer facility that creates new interbands energy states for the delay of electron-hole recombination, which cater the environmental remediation.
The hole density of individual copper sulfide nanocrystals (Cu2-xS NCs) is determined from the st... more The hole density of individual copper sulfide nanocrystals (Cu2-xS NCs) is determined from the stoichiometric mismatch (x) between copper and sulfide atoms. Consequently, the electronic properties of the material vary over a range of x. To exploit Cu2-xS NCs in devices, assemblies of NCs are typically required. Herein, we investigate the influence of x, referred to as the stoichiometric doping effect, on the structural, optical, electrical, and thermoelectric properties of electronically coupled Cu2-xS NC assemblies. The doping process is done by immersing the solid NC assemblies into a solution containing a Cu(I) complex for different durations (0-10 min). As Cu+ gradually occupied the copper-deficient sites of Cu2-xS NCs, x could be controlled from 0.9 to less than 0.1. Consequently, the near-infrared (NIR) absorbance of Cu2-xS NC assemblies changes systematically with x. With increasing x, electrical conductivity increased and the Seebeck coefficient decreased systematically, leading to the maximal thermoelectric power factor from a film of Cu2-xS NCs at an optimal doping condition yielding x = 0.1. The physical characteristics of the Cu2-xS NC assemblies investigated herein will provide guidelines for exploiting this emerging class of nanocrystal system based on doping.
The microwave hydrothermal and photo-reduction/deposition methods were employed to synthesize sil... more The microwave hydrothermal and photo-reduction/deposition methods were employed to synthesize silver nanoparticles (Ag NPs) decorated α-Nickel molybdate (α-NiMoO 4) nanorods. TEM image clearly shows the decoration of Ag NPs on α-NiMoO 4 nanorods. The Ag NPs decorated α-NiMoO 4 revealed eight folds increase in photocatalytic degradation of tetracycline (TC) compared to the α-NiMoO 4 under visible light irradiation. The photocatalyst shows excellent stability even after 5 th cycle of TC degradation as confirmed by XRD, XPS, and FESEM measurements. In addition, the photocatalyst shows anti-photo corrosion properties. TOC analysis and fluorescence spectroscopy analysis indicate the efficient degradation and mineralization of TC. The enhanced photocatalytic activities of photocatalyst could be attributed to increase in visible light absorption, SPR effect, and efficient separation of electron-hole pairs. The suppression of charge recombination confirmed by PL spectra, transient photocurrent response, EIS, and CV. ESR measurement and scavenger experiment suggest that OH • plays a major role whereas O 2 •and h + show the minor role for TC degradation. In order to find out the transformation products in water and degradation pathways of TC, UPLC-PDA and HR-QTOF ESI/MS techniques were used. The five degradation pathways are designed for TC on the basis of demethylation, hydroxylation, dehydroxylation, oxidation, and deamination organic reactions. Moreover, the ESR measurement was used to prove the photocatalytic mechanism. So, this work could provide a fabrication of efficient photocatalyst for removal of pharmaceuticals pollutants from waste water as well as deeper insight into photocatalytic mechanism, transformation products, and degradation pathways of TC in water.
Bulletin of The Korean Chemical Society, Mar 16, 2023
We report the map of 20 reactions that take place during vapor‐phase photochemical dehydrogenatio... more We report the map of 20 reactions that take place during vapor‐phase photochemical dehydrogenation of ethanol on four metal‐doped TiO2 (Mn/TiO2, Mn = nanoparticles of Pd, Pt, Au, and Cu) under solar simulated light. The reactions are sensitively affected by the moisture amount and the nature of the carrier gas. To construct the above map, we also used CH3CHO, CH3CO2H, (C2H5O)2CHCH3, and CH3CO2C2H5, respectively, as an independent starting reagent. Amazingly, Mn/TiO2 not only serves as photocatalysts but also as thermocatalysts for various reactions that appear in the above map. The reaction is proposed to proceed by a radical mechanism in which photoinduced electron transfer from the valence band to the conduction band of TiO2 is the initial step and the subsequent electron injection from organic reactants to the hole in the TiO2 valence band. This report also features highly valuable unprecedented reactions, which bear great potential to be commercialized.
We report the map of 20 reactions that take place during vapor‐phase photochemical dehydrogenatio... more We report the map of 20 reactions that take place during vapor‐phase photochemical dehydrogenation of ethanol on four metal‐doped TiO2 (Mn/TiO2, Mn = nanoparticles of Pd, Pt, Au, and Cu) under solar simulated light. The reactions are sensitively affected by the moisture amount and the nature of the carrier gas. To construct the above map, we also used CH3CHO, CH3CO2H, (C2H5O)2CHCH3, and CH3CO2C2H5, respectively, as an independent starting reagent. Amazingly, Mn/TiO2 not only serves as photocatalysts but also as thermocatalysts for various reactions that appear in the above map. The reaction is proposed to proceed by a radical mechanism in which photoinduced electron transfer from the valence band to the conduction band of TiO2 is the initial step and the subsequent electron injection from organic reactants to the hole in the TiO2 valence band. This report also features highly valuable unprecedented reactions, which bear great potential to be commercialized.
The characteristic NIR of copper sulfide nanocrystals (Cu2−xS NCs) assemblies based on the LSPR c... more The characteristic NIR of copper sulfide nanocrystals (Cu2−xS NCs) assemblies based on the LSPR can be controlled by exploiting monovalent lithium ions through electrochemical methods.
Lately, the upsurge in the liberation of synthetic dyes into the environment, primarily by the te... more Lately, the upsurge in the liberation of synthetic dyes into the environment, primarily by the textile industries, is a threat to the natural habitat and existing ecosystem. Various methods such as adsorption and degradation with nanoparticles are currently being used to degrade those hazardous materials, but still, the yearning for novel methods continues. In this study, hydrothermal reactions were performed at 160°C to synthesize manganese dioxide nanostructures (MnNSs) under different incubation periods that facilitated the comparison of the size, morphology, and crystallinity of MnNSs. The study revealed the change in crystallinity over the incubation period; MnNSs prepared at 24 hrs were highly crystalline among others. Additionally, the size and morphology of MnNSs changed from the sea-urchin or flower-like structure, predominantly sheet/layer form, to nanorods as the reaction proceeded for 24 hrs. Characterization of MnNSs was followed by heterogeneous Fenton’s reaction, usin...
The hole density of individual copper sulfide nanocrystals (Cu2-xS NCs) is determined from the st... more The hole density of individual copper sulfide nanocrystals (Cu2-xS NCs) is determined from the stoichiometric mismatch (x) between copper and sulfide atoms. Consequently, the electronic properties of the material vary over a range of x. To exploit Cu2-xS NCs in devices, assemblies of NCs are typically required. Herein, we investigate the influence of x, referred to as the stoichiometric doping effect, on the structural, optical, electrical, and thermoelectric properties of electronically coupled Cu2-xS NC assemblies. The doping process is done by immersing the solid NC assemblies into a solution containing a Cu(I) complex for different durations (0-10 min). As Cu+ gradually occupied the copper-deficient sites of Cu2-xS NCs, x could be controlled from 0.9 to less than 0.1. Consequently, the near-infrared (NIR) absorbance of Cu2-xS NC assemblies changes systematically with x. With increasing x, electrical conductivity increased and the Seebeck coefficient decreased systematically, leading to the maximal thermoelectric power factor from a film of Cu2-xS NCs at an optimal doping condition yielding x = 0.1. The physical characteristics of the Cu2-xS NC assemblies investigated herein will provide guidelines for exploiting this emerging class of nanocrystal system based on doping.
Abstract We studied the nucleation and growth of TiO2 nanoflowers and carbon nanotubes-TiO2 nanoc... more Abstract We studied the nucleation and growth of TiO2 nanoflowers and carbon nanotubes-TiO2 nanocomposite (n-CNT-TiO2) by the hydrothermal method in a single step at 150 °C and tested them for the photocatalytic degradation of MB. The microstructural analysis confirmed the transformation of TiO2 nanoflowers to CNT-TiO2 spheres due to the role of surface energy of CNT. The XRD peak profile analysis of TiO2 and n-CNT-TiO2 confirmed the formation of pure rutile phase of Titania sintered at 400 °C. A red-shift in the bandgap of n-CNT-TiO2 nanocomposite (2.7eV) was observed due to the donor states towards the conduction band edge. The core-level of XPS showed the strong interaction between carbon and titanium atoms. The CNT facilitate the interfacial charge transfer or avoid the formation of charge recombination due to the variation of Ti4+ to Ti3+ sites. The highest photocatalytic degradation was achieved by using the photocatalyst of n-CNT-TiO2 nanocomposite. The incorporation of CNT provides the interfacial charge transfer facility that creates new interbands energy states for the delay of electron-hole recombination, which cater the environmental remediation.
A novel type of adsorbent, TiO2 impregnated pomegranate peels (PP@TiO2) was successfully synthesi... more A novel type of adsorbent, TiO2 impregnated pomegranate peels (PP@TiO2) was successfully synthesized and its efficacy was investigated based on the removal of As(III) from water. The adsorbent was characterized using Scanning Electron Microscopy (SEM), Energy Dispersive X-ray Spectrometer (EDS), X-ray Diffraction (XRD) analysis, and Fourier Transform Infrared (FTIR) Spectroscopy, to evaluate its morphology, elemental analysis, crystallinity, and functional groups, respectively. Batch experiments were conducted on PP@TiO2 for As(III) adsorption to assess the adsorption isotherm, effect of pH, and adsorption kinetics. Characterization data suggested that TiO2 was successfully impregnated on the biomass substrate. The equilibrium data better fitted to the Langmuir isotherm model having a maximum adsorption capacity of 76.92 mg/g and better distribution coefficients (KD) in the order of ~103 mL/g. The highest percentage of adsorption was found at neutral pH. The adsorption kinetics foll...
Abstract We synthesized yttrium-doped CNT-ZnO (CNT-YZO) nanoparticles (NPs) and nanoflowers (NFs)... more Abstract We synthesized yttrium-doped CNT-ZnO (CNT-YZO) nanoparticles (NPs) and nanoflowers (NFs) from the hydrothermal method at 130 °C. The effect of Y3+-concentrations in nanostructured CNT-YZO was determined in terms of the photocatalytic degradation of methylene blue (MB). Microstructural analysis showed the hexagonal cubic structure of ZnO regardless of Y-concentration or the addition of CNTs during the nucleation and growth. The specific surface area, total pore volume, and mean pore diameter of typical CNT-YZO NFs were observed to be 36.109 m2/g, 0.162 cm3/g, and 17.932 nm, respectively. The photocatalytic degradation performance of CNT-YZO NFs improved due to increase reactive sites of the catalyst and reduced recombination of photo-induced carriers. The surface-area normalized first-order decomposition rates (r/m2) of CNT-YZO NFs showed the highest photocatalytic degradation (99%). The CNT-YZO has produced a new kind of material for the photocatalytic degradation under the irradiation of visible light using a solar simulator.
Zinc oxide (ZnO) nanorods incorporated activated carbon (AC) composite photocatalyst was synthesi... more Zinc oxide (ZnO) nanorods incorporated activated carbon (AC) composite photocatalyst was synthesized using a hydrothermal process. The AC was prepared from lapsi (Choerospondias axillaris) seed stone, an agricultural waste product, found in Nepal by the chemical activation method. An aqueous suspension of AC with ZnO precursor was subjected to the hydrothermal treatment at 140 °C for 2 h to decorate ZnO rods into the surface of AC. As-obtained ZnO nanorods decorated activated carbon (ZnO/AC) photocatalyst was characterized by various techniques, such as scanning electron microscopy (SEM), X-ray diffraction (XRD), and photoluminescence (PL) spectroscopy. Results showed that highly crystalline hexagonal ZnO nanorods were effectively grown on the surface of porous AC. The photocatalytic property of the as-prepared ZnO/AC composite was studied by degrading methylene blue (MB) dye under UV-light irradiation. The ZnO/AC composite showed better photocatalytic property than that of the pris...
Polymeric microspheres from polylactide and infusion of Woodfordia fruticosa flower were prepared... more Polymeric microspheres from polylactide and infusion of Woodfordia fruticosa flower were prepared using emulsion-solvent evaporation method. The obtained microspheres were spherical to oval in shape with the size ranging from 1-29.8 µM with WFPM-2 yielding the major population within a range of 1-6 µm.
Porous activated carbon (AC) and magnetic iron oxide nanoparticles (NPs) are widely used for the ... more Porous activated carbon (AC) and magnetic iron oxide nanoparticles (NPs) are widely used for the removal of arsenic from water body. Fabrication of composite material of iron oxide NPs on the surface of porous AC can further enhance this activity for commercial application. In this research, a magnetic AC composite for arsenic adsorption was prepared by facile hydrothermal treatment of aqueous solution containing activated carbon obtained from lapsi seed stone, iron(II) chloride, polyvinylpyrrolidone (PVP) and ethanol. Several analytical techniques such as scanning electron microscopy (SEM), energy dispersive x-ray (EDX), X-ray diffraction (XRD) and Fourier-transform infrared spectroscopy (FTIR) confirmed the formation of magnetite (Fe3O4) nanoparticles on the surface of porous AC. The prepared materials were accessed for their arsenic adsorption capacity using arsenic (III) trioxide solution and found that composite Fe2O3/AC can remove the arsenic from water far more effectively th...
Activated carbon is greatly used to adsorb toxic heavy metals from water bodies. Simultaneous re... more Activated carbon is greatly used to adsorb toxic heavy metals from water bodies. Simultaneous removal of such pollutants and pathogenic impurities is essential for safe drinking water. In this study, silver nanoparticles (NPs) doped activated carbon (AC) composite was fabricated via hydrothermal technique and green synthesis technique using commercial activated carbon powder and silver nitrate solution. Several analytical techniques, including scanning electron microscopy (SEM), energy dispersive x-ray (EDX), X-ray diffraction (XRD) and Fourier-transform infrared spectroscopy (FTIR) confirmed the formation of silver nanoparticles on the surface and pores of AC. The prepared composite materials were accessed for their anti-bacterial property using Escherichia coli and Staphylococcus aureus and found that such materials have good antibacterial activity which shows that as fabricated composite can be used potentially for water treatment.
Plant-mediated synthesis of silver nanoparticles through green chemistry approach has evolved int... more Plant-mediated synthesis of silver nanoparticles through green chemistry approach has evolved into a new era of research; however, the heterogeneous size and dispersity of silver nanoparticles have limited its applications, such as surface-enhanced Raman scattering, plasmon resonance, and more specifically in the medical field of target drug delivery and therapeutic activity. Here-we investigated the effect of purification and separation modes on the dispersity, size, and morphology of silver nanoparticles, synthesized by plant extract (Nyctanthes arbor-tristis). Transmission electron microscopy revealed silver nanoparticles with an average diameter of 13.0 nm when synthesized through ethanol precipitation, which is advantageously smaller. This result suggests that the silver nanoparticles size can be fine-tuned by changing the separation mode during purification from plant extract. Due to uniformity, our obtained nanoparticles can be expected to show higher catalytic activity towar...
The microwave hydrothermal and photo-reduction/deposition methods were employed to synthesize sil... more The microwave hydrothermal and photo-reduction/deposition methods were employed to synthesize silver nanoparticles (Ag NPs) decorated α-Nickel molybdate (α-NiMoO 4) nanorods. TEM image clearly shows the decoration of Ag NPs on α-NiMoO 4 nanorods. The Ag NPs decorated α-NiMoO 4 revealed eight folds increase in photocatalytic degradation of tetracycline (TC) compared to the α-NiMoO 4 under visible light irradiation. The photocatalyst shows excellent stability even after 5 th cycle of TC degradation as confirmed by XRD, XPS, and FESEM measurements. In addition, the photocatalyst shows anti-photo corrosion properties. TOC analysis and fluorescence spectroscopy analysis indicate the efficient degradation and mineralization of TC. The enhanced photocatalytic activities of photocatalyst could be attributed to increase in visible light absorption, SPR effect, and efficient separation of electron-hole pairs. The suppression of charge recombination confirmed by PL spectra, transient photocurrent response, EIS, and CV. ESR measurement and scavenger experiment suggest that OH • plays a major role whereas O 2 •and h + show the minor role for TC degradation. In order to find out the transformation products in water and degradation pathways of TC, UPLC-PDA and HR-QTOF ESI/MS techniques were used. The five degradation pathways are designed for TC on the basis of demethylation, hydroxylation, dehydroxylation, oxidation, and deamination organic reactions. Moreover, the ESR measurement was used to prove the photocatalytic mechanism. So, this work could provide a fabrication of efficient photocatalyst for removal of pharmaceuticals pollutants from waste water as well as deeper insight into photocatalytic mechanism, transformation products, and degradation pathways of TC in water.
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Papers by Agni Koirala