Ambesh Dixit

Developing high‐performance energy storage devices is essential to meet the rising energy demands. The present work demonstrates the improved electrochemical properties of rGO/ZFO by Mg, Mn codoping approach. The incorporation of rGO (reduced graphene oxide) with dual‐doped zinc ferrite significantly improves charge storage behavior, thereby enhancing the capacitance. The doping of Mg and Mn is ensured by X‐ray diffraction (XRD), while Brunauer–Emmett–Teller (BET) shows the enhanced surface area due to doping. Dielectric permittivity ( ε ) and tangent loss (tan δ ) were analyzed over different frequency ranges. Electrochemical performance was evaluated using both three‐electrode and symmetric coin‐cell (SCC) configurations. In the 3‐electrode system, the specific capacitance ( C _sp ) was found to be 157.39 and 376.68 F g ⁻¹ while corresponding SCC devices deliver 68.17 and 90.57 F g ⁻¹ at 1 mV s ⁻¹ . The energy density ( E _D ) and powder density ( P _D ) was 8.22 and 14.26 Wh kg ⁻¹ and 28.7 and 28.8 W kg ⁻¹ at 0.04 A g ⁻¹ for rGO/ZFO and Mg, Mn doped rGO/ZFO SCC, respectively. Moreover, the Mg, Mn doped rGO/ZFO SCC device shows an exceptional capacitance retention of 96% after 10 000 cycles at 0.4 A g ⁻¹ . These results highlight the effectiveness of dual doping and rGO incorporation in advancing zinc ferrite‐based supercapacitors (SCs).

The use of photo-assisted rechargeable batteries integrating solar harvesting and electrochemical storage represents a sustainable approach for next-generation energy devices.

A corrugated diaphragm based 4H-SiC piezoresistive pressure sensor is designed and investigated for high-temperature pressure-sensing applications. The sensor consists of a square corrugated diaphragm integrated with four piezoresistors arranged in full Wheatstone bridge configuration to enhance stress and pressure sensitivity. Finite element simulations are performed over a pressure range of 0-20MPa & temperature range of 25°C-500°C. The influence of corrugated geometry on mechanical and electrical performance is evaluated, where a five-ring corrugated diaphragm exhibited the highest sensitivity among others. Temperature-dependent analyses reveal that the maximum diaphragm displacement increased from 27.11μm at 25°C to 43.85μm at 500°C, while maximum stress increased from 4001.9MPa to 6181 MPa. The sensor exhibited a linear response of output voltage with pressure at different temperatures. The output voltage and sensitivity decreased with increasing temperature due to reduction in piezoresistive coefficients of 4H SiC. The sensitivity decreases from 857.29μV/MPa at 25°C to 373.4μV/MPa at 500°C. Thermal stability of sensor is also investigated through temperature coefficient of offset (ranging between -147 ppm/°C and -45 ppm/°C), temperature coefficient of sensitivity, and temperature coefficient of resistance (TCR) (lies within 117-172 ppm/°C) analyses. Noise performance also evaluated, showing the sensor maintains output noise voltage below 1.4µV, a signal to noise ratio (SNR) greater than 75dB & a minimum detectable pressure (MDP) of 3.56kPa even at 500°C. The obtained results show that corrugated 4H SiC MEMS pressure sensors offer high sensitivity, good thermal stability and excellent pressure resolution, making them suitable for harsh environment sensing applications.

Carbonaceous Chondrites have special significance in the stellar evolution and in particular in the evolution of life on earth. The carbonaceous meteorite that fell in Mukundpura village, Jaipur, Rajasthan on 6th June 2017 is one such rare CM2 carbonaceous meteorite. We carried out high resolution scanning and transmission electron microscopic studies on typical thin sections, showing abundant grains of iridium, pentlandite, and more interestingly crystalline carbon. These crystallite carbon grains resemble nanodiamond like signature in the freshest Mukundpura meteorite. The high-resolution Raman spectroscopic measurements are carried out on the crystalline carbon grains, showing well resolved three distinct peaks with a vibrational mode at 1315 cm-1, with the onset of a weak vibrational mode at 1150 cm-1, substantiating the observation of nanocrystalline diamond in Mukundpura meteorite. The broad peak centered at 1360 cm-1 and 1575 cm-1 (as an average), suggest the presence of graphitic carbon as well together with apparent presence of nanocrystalline diamond. The average size of nanocrystalline diamond is ~ 3-5 nm. High iridium content in this meteorite supports the meteoric impact related iridium anomaly in geological stratigraphic boundaries (e.g. Cretaceous-Tertiary boundary) that has caused mass extinction of flora and fauna.

Electrochemical water splitting has emerged as a promising route to sustainable, green hydrogen production, playing a key role in advancing clean energy systems. The continued advancement of water electrolysis relies heavily on the rational design and evaluation of efficient, durable, and cost-effective electrocatalysts. However, a meaningful and fair comparison of electrocatalyst performance depends on accurate and standardized measurement protocols. This tutorial provides an in-depth overview of the best measurement practices for assessing performance parameters, including overpotential, Tafel slope, charge transfer, electrolyte resistance, electrochemical surface area, turnover frequency, stability, and Faradaic efficiency of electrocatalysts for water splitting. More emphasis is given on highlighting the strengths and limitations of various electrochemical methods, such as linear sweep voltammetry (LSV), cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), chronoamperometry (CA), and chronopotentiometry (CP). Further, special attention is given to proper iR compensation, selection of appropriate scan rates, and identification of the non-Faradaic region for accurate determination of electrochemical surface area (ECSA). The role of redox peak integration in estimating active site densities, particularly for transition-metal-based electrocatalysts, is also a focus. The transition from standard three-electrode testing to a full-cell alkaline water electrolyzer is also discussed in detail, highlighting standard protocols to minimize the gap between lab-scale testing and commercial-scale electrolyzers. Thus, overall, this tutorial can be considered a practical guide for academicians and researchers, especially beginners in the field, aiming to enhance the reliability of electrochemical measurements and further catalyze the innovation and development of high-performance, energy-efficient water-splitting electrocatalysts for green hydrogen production.

In this study experimental nanoindentation-derived mechanical properties of a-SiC were directly integrated into finite element simulations to establish the relationship between annealing-induced mechanical evolution and MEMS pressure sensor performance. The a-SiC thin films were deposited on Si substrates by RF sputtering system and later annealed at 10000 C for 1 hour and 2 hours to investigate the effect of thermal treatment on their mechanical properties and MEMS pressure sensor performance. Surface morphology was evaluated by atomic force microscopy, while the nanoindentation technique was used to determine the nanomechanical properties, including hardness, elastic modulus, stiffness, contact depth, and depth recovery ratio. The nanoindentation results revealed a significant reduction in hardness from 37.05 GPa for pristine to 14.82 GPa after 2 hours annealing. Also, a reduction in elastic modulus is also seen from 282.9 GPa for unannealed sample to 156.88 GPa for the 2 hours annealed sample. The increase in contact depth indicates structural relaxation and softening of SiC thin films after annealing. Based on experimentally obtained mechanical properties, SiC-based piezoresistive pressure sensor was designed and simulated over the pressure range of 1-10 MPa. The annealed samples exhibited higher diaphragm displacement, von Mises stress and strain due to reduced hardness, and stiffness. The estimated sensitivity of the sensor structure is 71.47 µV/V/MPa (unannealed), 70.97 µV/V/MPa (1 hour annealed) and 70.47 µV/V/MPa (2 hours annealed), with < 1% (full-scale) non-linearity. The results establish a direct correlation between the mechanical properties and pressure sensor performance induced by annealing.