The electrocatalytic behavior of glassy carbon (GC) electrode modified with ruthenium nanoparticl... more The electrocatalytic behavior of glassy carbon (GC) electrode modified with ruthenium nanoparticles and ruthenium film was studied for electrochemical reduction of nicotinamide adenine dinucleotide (NAD+). The surface of GC electrode was modified via cathodic deposition of nanosized ruthenium at different potentials. Scanning electron microscopy (SEM) images showed two kinds of surface morphologies based on deposition potential: Ru nanoparticles-decorated GC at −0.3 V and Ru film-coated GC at −0.5 V versus Ag/AgCl. The electrochemical behavior of Ru nanoparticles and Ru film-modified GC electrodes in phosphate buffer solution containing NAD+ was investigated using voltammetric techniques. A prominent cathodic peak was observed on bare GC and Ru nanoparticles-modified GC at −1.2 V versus Ag/AgCl which was related to NAD+ reduction. The electrochemical response of Ru film electrode was reversible, exhibiting a reduction peak at ca. −1.0 V and an oxidation peak at ca. −0.55 V which was attributed mainly to the hydrogen evolution reaction. Electrochemical impedance analysis indicated lower charge transfer resistance of Ru film electrode for hydrogen evolution as compared to GC and Ru nanoparticle electrodes. Ru film-modified electrode was found less reactive than the nanoparticles-modified GC electrode for NAD+ reduction reaction due to hydrogen evolution reaction that proceeds exclusively on Ru film.Graphical Abstract
Abstract Metal oxide-metal sulfide-based composites of desired properties are of great technologi... more Abstract Metal oxide-metal sulfide-based composites of desired properties are of great technological importance because of their applications ranging from photovoltaics to energy storage devices. Herein, we report on the structural and charge storage capabilities of nickel-doped zinc sulfide-decorated zinc oxide (Ni–ZnS/ZnO) composite prepared by wet chemical route. The synthesis of ZnO, Ni–ZnS, and Ni–ZnS/ZnO was performed at 80 °C in a single vessel which was followed by annealing at 300 °C for 1 h. Scanning electron microscopy (SEM) images indicated flower-like morphology of the ZnO decorated with Ni-doped ZnS (Ni–ZnS). The material exhibited characteristic X-ray diffraction (XRD) signals corresponding to ZnO and Ni–ZnS which confirmed the formation of a composite structure. Energy-dispersive X-ray analysis, UV–visible spectroscopy, and Fourier Transform Infrared (FTIR) spectroscopy measurements revealed the successful formation of Ni–ZnS/ZnO composites. Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) were carried out to examine the energy storage capabilities of the synthesized Ni–ZnS/ZnO composite. The composite electrode demonstrated a specific capacitance of 354 F g−1 in 1 M KOH electrolyte which was higher than that of the Ni–ZnS (154.7 F g−1) and ZnO (132 F g−1). The enhanced capacitive performance of the composite is attributed to the low charge transfer resistance and high electrochemically active specific surface area (27.54 m2 g−1), as revealed by EIS results.
Transition-metal sulfides with nanostructured features grown on a conductive substrate have been ... more Transition-metal sulfides with nanostructured features grown on a conductive substrate have been suggested as a promising alternative to precious metal-based electrocatalysts for energy conversion ...
A simple and one-step all solution-processed deposition of NixSy on a stainless steel substrate w... more A simple and one-step all solution-processed deposition of NixSy on a stainless steel substrate with controlled surface morphology dictated by the growth temperature and excellent electrochemical charge storage capabilities is presented.
A cathode material containing Ni content over 80% suffers from a poor cycling performance, despit... more A cathode material containing Ni content over 80% suffers from a poor cycling performance, despite its promising performance in a lithium ion battery. By utilizing the first-principles calculation, we show that the stability and electrochemical performance of the NCM-89 material, LiNi0.89Co0.055Mn0.055O2, can be enhanced by doping with zirconium (+4) or molybdenum (+6). The present doping increases Ni2+s in the NCM-89 material and stabilizes the layer of transition metal by strengthening the Zr−O and Mo−O
bonds. The doping also suppresses the phase transition from a layered-oxide to a spinel structure by restraining the migration of Ni2+ and thereby mitigating the release of an oxygen gas.
Titanium dioxide (TiO2) has been investigated for solar-energy-driven photoelectrical water split... more Titanium dioxide (TiO2) has been investigated for solar-energy-driven photoelectrical water splitting due to its suitable band gap, abundance, cost savings, environmental friendliness, and chemical stability. However, its poor conductivity, weak light absorption, and large indirect bandgap (3.2 eV) has limited its application in water splitting. In this study, we precisely targeted these limitations using first-principle techniques. TiO2 only absorbs near-ultraviolet radiation; therefore, the substitution (2.1%) of Ag, Fe, and Co in TiO2 significantly altered its physical properties and shifted the bandgap from the ultraviolet to the visible region. Cobalt (Co) substitution in TiO2 resulted in high absorption and photoconductivity and a low bandgap energy suitable for the reduction in water without the need for external energy. The calculated elastic properties of Co-doped TiO2 indicate the ductile nature of the material with a strong average bond strength. Co-doped TiO2 exhibited f...
Simple Summary Nanocarriers have been used to solve the problems associated with conventional ant... more Simple Summary Nanocarriers have been used to solve the problems associated with conventional antitumor drug delivery systems, including no specificity, severe side effects, burst release and damaging the normal cells. It improves the bioavailability and therapeutic efficiency of antitumor drugs, while providing preferential accumulation at the target site. Various 2D nanomaterials such as graphene, MoS2, and WSe2 have been used as nanocarrier. The recent discovery of phosphorene has introduced new possibilities in designing a sensible drug delivery system, due to low cytotoxicity, biocompatibility, high surface to volume ratio, which can increase its drug loading capacity. The biodegradation of phosphorene inside the human body produces non-toxic intermediates, like phosphate. Phosphate is necessary for the formation of bone and teeth. Phosphate is also used by the cell for energy, cell membranes, and DNA (deoxyribonucleic acid). Therefore, phosphorene nanocarrier is not harmful, e...
Mussels have a remarkable ability to bond to solid surfaces under water. From a microscopic persp... more Mussels have a remarkable ability to bond to solid surfaces under water. From a microscopic perspective, the first step of this process is the adsorption of dopa molecules to the solid surface. In fact, it is the catechol part of the dopa molecule that is interacting with the surface. These molecules are able to make reversible bonds to a wide range of materials, even underwater. Previous experimental and theoretical efforts have produced only a limited understanding of the mechanism and quantitative details of the competitive adsorption of catechol and water on hydrophilic silica surfaces. In this work, we uncover the nature of this competitive absorption by atomic scale modeling of water and catechol adsorbed at the geminal (001) silica surface using density functional theory calculations. We find that catechol molecules displace preadsorbed water molecules and bond directly on the silica surface. Using molecular dynamics simulations, we observe this process in detail. We also calculate the interaction force as a function of distance, and observe a maximum of 0.5 nN of attraction. The catechol has a binding energy of 23 kcal/mol onto the silica surface with adsorbed water molecules.
The electrocatalytic behavior of glassy carbon (GC) electrode modified with ruthenium nanoparticl... more The electrocatalytic behavior of glassy carbon (GC) electrode modified with ruthenium nanoparticles and ruthenium film was studied for electrochemical reduction of nicotinamide adenine dinucleotide (NAD+). The surface of GC electrode was modified via cathodic deposition of nanosized ruthenium at different potentials. Scanning electron microscopy (SEM) images showed two kinds of surface morphologies based on deposition potential: Ru nanoparticles-decorated GC at −0.3 V and Ru film-coated GC at −0.5 V versus Ag/AgCl. The electrochemical behavior of Ru nanoparticles and Ru film-modified GC electrodes in phosphate buffer solution containing NAD+ was investigated using voltammetric techniques. A prominent cathodic peak was observed on bare GC and Ru nanoparticles-modified GC at −1.2 V versus Ag/AgCl which was related to NAD+ reduction. The electrochemical response of Ru film electrode was reversible, exhibiting a reduction peak at ca. −1.0 V and an oxidation peak at ca. −0.55 V which was attributed mainly to the hydrogen evolution reaction. Electrochemical impedance analysis indicated lower charge transfer resistance of Ru film electrode for hydrogen evolution as compared to GC and Ru nanoparticle electrodes. Ru film-modified electrode was found less reactive than the nanoparticles-modified GC electrode for NAD+ reduction reaction due to hydrogen evolution reaction that proceeds exclusively on Ru film.Graphical Abstract
Abstract Metal oxide-metal sulfide-based composites of desired properties are of great technologi... more Abstract Metal oxide-metal sulfide-based composites of desired properties are of great technological importance because of their applications ranging from photovoltaics to energy storage devices. Herein, we report on the structural and charge storage capabilities of nickel-doped zinc sulfide-decorated zinc oxide (Ni–ZnS/ZnO) composite prepared by wet chemical route. The synthesis of ZnO, Ni–ZnS, and Ni–ZnS/ZnO was performed at 80 °C in a single vessel which was followed by annealing at 300 °C for 1 h. Scanning electron microscopy (SEM) images indicated flower-like morphology of the ZnO decorated with Ni-doped ZnS (Ni–ZnS). The material exhibited characteristic X-ray diffraction (XRD) signals corresponding to ZnO and Ni–ZnS which confirmed the formation of a composite structure. Energy-dispersive X-ray analysis, UV–visible spectroscopy, and Fourier Transform Infrared (FTIR) spectroscopy measurements revealed the successful formation of Ni–ZnS/ZnO composites. Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) were carried out to examine the energy storage capabilities of the synthesized Ni–ZnS/ZnO composite. The composite electrode demonstrated a specific capacitance of 354 F g−1 in 1 M KOH electrolyte which was higher than that of the Ni–ZnS (154.7 F g−1) and ZnO (132 F g−1). The enhanced capacitive performance of the composite is attributed to the low charge transfer resistance and high electrochemically active specific surface area (27.54 m2 g−1), as revealed by EIS results.
Transition-metal sulfides with nanostructured features grown on a conductive substrate have been ... more Transition-metal sulfides with nanostructured features grown on a conductive substrate have been suggested as a promising alternative to precious metal-based electrocatalysts for energy conversion ...
A simple and one-step all solution-processed deposition of NixSy on a stainless steel substrate w... more A simple and one-step all solution-processed deposition of NixSy on a stainless steel substrate with controlled surface morphology dictated by the growth temperature and excellent electrochemical charge storage capabilities is presented.
A cathode material containing Ni content over 80% suffers from a poor cycling performance, despit... more A cathode material containing Ni content over 80% suffers from a poor cycling performance, despite its promising performance in a lithium ion battery. By utilizing the first-principles calculation, we show that the stability and electrochemical performance of the NCM-89 material, LiNi0.89Co0.055Mn0.055O2, can be enhanced by doping with zirconium (+4) or molybdenum (+6). The present doping increases Ni2+s in the NCM-89 material and stabilizes the layer of transition metal by strengthening the Zr−O and Mo−O
bonds. The doping also suppresses the phase transition from a layered-oxide to a spinel structure by restraining the migration of Ni2+ and thereby mitigating the release of an oxygen gas.
Titanium dioxide (TiO2) has been investigated for solar-energy-driven photoelectrical water split... more Titanium dioxide (TiO2) has been investigated for solar-energy-driven photoelectrical water splitting due to its suitable band gap, abundance, cost savings, environmental friendliness, and chemical stability. However, its poor conductivity, weak light absorption, and large indirect bandgap (3.2 eV) has limited its application in water splitting. In this study, we precisely targeted these limitations using first-principle techniques. TiO2 only absorbs near-ultraviolet radiation; therefore, the substitution (2.1%) of Ag, Fe, and Co in TiO2 significantly altered its physical properties and shifted the bandgap from the ultraviolet to the visible region. Cobalt (Co) substitution in TiO2 resulted in high absorption and photoconductivity and a low bandgap energy suitable for the reduction in water without the need for external energy. The calculated elastic properties of Co-doped TiO2 indicate the ductile nature of the material with a strong average bond strength. Co-doped TiO2 exhibited f...
Simple Summary Nanocarriers have been used to solve the problems associated with conventional ant... more Simple Summary Nanocarriers have been used to solve the problems associated with conventional antitumor drug delivery systems, including no specificity, severe side effects, burst release and damaging the normal cells. It improves the bioavailability and therapeutic efficiency of antitumor drugs, while providing preferential accumulation at the target site. Various 2D nanomaterials such as graphene, MoS2, and WSe2 have been used as nanocarrier. The recent discovery of phosphorene has introduced new possibilities in designing a sensible drug delivery system, due to low cytotoxicity, biocompatibility, high surface to volume ratio, which can increase its drug loading capacity. The biodegradation of phosphorene inside the human body produces non-toxic intermediates, like phosphate. Phosphate is necessary for the formation of bone and teeth. Phosphate is also used by the cell for energy, cell membranes, and DNA (deoxyribonucleic acid). Therefore, phosphorene nanocarrier is not harmful, e...
Mussels have a remarkable ability to bond to solid surfaces under water. From a microscopic persp... more Mussels have a remarkable ability to bond to solid surfaces under water. From a microscopic perspective, the first step of this process is the adsorption of dopa molecules to the solid surface. In fact, it is the catechol part of the dopa molecule that is interacting with the surface. These molecules are able to make reversible bonds to a wide range of materials, even underwater. Previous experimental and theoretical efforts have produced only a limited understanding of the mechanism and quantitative details of the competitive adsorption of catechol and water on hydrophilic silica surfaces. In this work, we uncover the nature of this competitive absorption by atomic scale modeling of water and catechol adsorbed at the geminal (001) silica surface using density functional theory calculations. We find that catechol molecules displace preadsorbed water molecules and bond directly on the silica surface. Using molecular dynamics simulations, we observe this process in detail. We also calculate the interaction force as a function of distance, and observe a maximum of 0.5 nN of attraction. The catechol has a binding energy of 23 kcal/mol onto the silica surface with adsorbed water molecules.
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bonds. The doping also suppresses the phase transition from a layered-oxide to a spinel structure by restraining the migration of Ni2+ and thereby mitigating the release of an oxygen gas.
bonds. The doping also suppresses the phase transition from a layered-oxide to a spinel structure by restraining the migration of Ni2+ and thereby mitigating the release of an oxygen gas.