Andrews Nirmala Grace

Bio: Andrews Nirmala Grace is an academic researcher from VIT University. The author has contributed to research in topics: Graphene & Cyclic voltammetry. The author has an hindex of 31, co-authored 97 publications receiving 3183 citations.

Development of Cu3N electrocatalyst for hydrogen evolution reaction in alkaline medium

Abstract: A wide variety of electrocatalysts has been evolved for hydrogen evolution reaction (HER) and it is reasonable to carry out HER with low cost electrocatalyst and a good efficiency. In this study, Cu3N was synthesized by nitridation of Cu2O and further utilized as an electrocatalyst towards HER. The developed Cu3N electrocatalyst was tested and results showed a low overpotential and moderate Tafel slope value (overpotential: 149.18 mV and Tafel slope 63.28 mV/dec at 10 mA/cm2) in alkaline medium with a charge transfer resistance value as calculated from electrochemical impendence spectroscopy being 1.44 Ω. Further from the experimental results, it was observed that the reaction kinetics was governed by Volmer-Heyrovsky mechanism. Moreover, Cu3N has shown an improved rate of electron transfer and enhanced accessible active sites, due to its structural properties and electrical conductivity. Thus the overall results show an excellent electrochemical performance, leading to a new pathway for the synthesis of low cost electrocatalyst for energy conversion and storage.

Thermal decomposition derived nano molybdenum nitride for robust counter electrode in dye-sensitized solar cells

Abstract: The unique category of transition metal nitrides has an immense scope as an electron-driven catalyst in redox reactions However, synthesizing metal nitrides without contamination is very challenging The residues present in the catalyst might affect catalytic activity This work reports a simple synthesis of contamination-free nanoscale molybdenum nitride (Mo2N) powder by integrated wet chemical and thermal decomposition techniques at 800 °C Systematic structural and morphological studies were done, which shows the spherical shape of γ -Mo2N nanoparticles Electrochemical and photovoltaic characteristics were studied using cyclic voltammetry, electrochemical impedance spectroscopy (EIS), Tafel polarization and J–V characteristics As a result of high electrolyte diffusivity, less charge transfer resistance, high electrochemical stability and catalytic activity, the nano Mo2N based DSSCs exhibits 53 % efficiency, which is comparable to Pt-based device (64 %) fabricated under the similar condition that is 837 % of the performance offered by an expensive counter electrode This simple synthesis method could enable low-cost mass production of Mo2N nanoparticles as counter electrodes in DSSC The developed counter electrodes may be a suitable alternative for stable, efficient and low-cost DSSCs

2D non-carbide MXenes: an emerging material class for energy storage and conversion

Abstract: Since the first discovery of MXene in 2011, various compositions of MXenes have been developed based on the combinations of different transition metals. Their exceptional and intriguing properties, such as...

Process optimisation for green synthesis of ZnO nanoparticles and evaluation of its antimacrofouling activity

Abstract: In recent years, considerable attention has been given to the plant-mediated synthesis of nanoparticles because it is an eco-friendly method compared to the synthesis by chemical route. This study aims to optimise the biosynthesis of zinc oxide nanoparticles (ZnO-NPs) mediated by coconut water using response surface methodology (RSM). The effects of the individual variables (concentration of coconut water, temperature and time) and their interactions during the biosynthesis of ZnO-NPs were determined by RSM employing Box-Behnken design. The variables selected were tested by a 17-run experiment and quadratic model was used for the analysis of the results. The accuracy of the model was confirmed by the coefficient of determination ( R 2 ) value of 0.9968. The significance of the regression model was found to be high which is validated by the low probability value of P <; 0.0001. The ZnO-NPs thus synthesised was evaluated for its antimacrofouling activity against mollusks using in-vitro foot-adherence bioassay. The results demonstrated the potential of biosynthesised ZnO-NPs in inhibiting fouling induced due to the test organisms.

I and i

Abstract: There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality. Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

Fast parallel algorithms for short-range molecular dynamics

Abstract: Three parallel algorithms for classical molecular dynamics are presented. The first assigns each processor a fixed subset of atoms; the second assigns each a fixed subset of inter-atomic forces to compute; the third assigns each a fixed spatial region. The algorithms are suitable for molecular dynamics models which can be difficult to parallelize efficiently—those with short-range forces where the neighbors of each atom change rapidly. They can be implemented on any distributed-memory parallel machine which allows for message-passing of data between independently executing processors. The algorithms are tested on a standard Lennard-Jones benchmark problem for system sizes ranging from 500 to 100,000,000 atoms on several parallel supercomputers--the nCUBE 2, Intel iPSC/860 and Paragon, and Cray T3D. Comparing the results to the fastest reported vectorized Cray Y-MP and C90 algorithm shows that the current generation of parallel machines is competitive with conventional vector supercomputers even for small problems. For large problems, the spatial algorithm achieves parallel efficiencies of 90% and a 1840-node Intel Paragon performs up to 165 faster than a single Cray C9O processor. Trade-offs between the three algorithms and guidelines for adapting them to more complex molecular dynamics simulations are also discussed.

Mn3O4-Graphene Hybrid as a High Capacity Anode Material for Lithium Ion Batteries

Abstract: We developed two-step solution-phase reactions to form hybrid materials of Mn3O4 nanoparticles on reduced graphene oxide (RGO) sheets for lithium ion battery applications. Mn3O4 nanoparticles grown selectively on RGO sheets over free particle growth in solution allowed for the electrically insulating Mn3O4 nanoparticles wired up to a current collector through the underlying conducting graphene network. The Mn3O4 nanoparticles formed on RGO show a high specific capacity up to ~900mAh/g near its theoretical capacity with good rate capability and cycling stability, owing to the intimate interactions between the graphene substrates and the Mn3O4 nanoparticles grown atop. The Mn3O4/RGO hybrid could be a promising candidate material for high-capacity, low-cost, and environmentally friendly anode for lithium ion batteries. Our growth-on-graphene approach should offer a new technique for design and synthesis of battery electrodes based on highly insulating materials.

Recent Advances in Inorganic Heterogeneous Electrocatalysts for Reduction of Carbon Dioxide

Abstract: In view of the climate changes caused by the continuously rising levels of atmospheric CO2 , advanced technologies associated with CO2 conversion are highly desirable. In recent decades, electrochemical reduction of CO2 has been extensively studied since it can reduce CO2 to value-added chemicals and fuels. Considering the sluggish reaction kinetics of the CO2 molecule, efficient and robust electrocatalysts are required to promote this conversion reaction. Here, recent progress and opportunities in inorganic heterogeneous electrocatalysts for CO2 reduction are discussed, from the viewpoint of both experimental and computational aspects. Based on elemental composition, the inorganic catalysts presented here are classified into four groups: metals, transition-metal oxides, transition-metal chalcogenides, and carbon-based materials. However, despite encouraging accomplishments made in this area, substantial advances in CO2 electrolysis are still needed to meet the criteria for practical applications. Therefore, in the last part, several promising strategies, including surface engineering, chemical modification, nanostructured catalysts, and composite materials, are proposed to facilitate the future development of CO2 electroreduction.