The establishment of an economic means of hydrogen production by electrochemical water‐splitting can help alleviate the intermittency problem associated with renewable energy sources such as solar and wind, and also provide for the extensive commercialization of fuel cell technologies. To enable this, cheap, active, and stable hydrogen evolution catalysts that can replace precious metal catalysts such as Pt must be developed. Herein, a scalable synthesis of porous Mo2C nanostructures derived from biochar, an inexpensive plant byproduct, is reported. The Mo2C catalyst materials prepared using this solid‐state method, loaded on planar substrates, require overpotentials of only 35 and 60 mV to drive current densities of −10 and −100 mA cm−2 in 0.50 m H2SO4 solution and exhibit stable operation for >100 h at operating current densities of −10 and −100 mA cm−2.
A highly selective, ultrasensitive (visual and instrumental detection limits of 40 nM and 0.1 nM, respectively), environmentally-friendly, simple and rapid colorimetric sensor was developed for the detection of copper(II) in water. This sensor is based on a novel signal-amplification mechanism involving reactive halide species (RHSs) including chlorides or bromides, which accelerate copper Fenton reactions oxidizing the chromogenic substrate to develop colour. The results of this study expand our understanding of copper-based Fenton chemistry.
Magnesiothermic reduction of silicon oxide can result in the formation of nanostructured, mesoporous elemental silicon (mp-Si), which has been explored in a variety of energy applications such as Li-ion battery anodes, photocatalytic water splitting, CO 2 reduction, drug delivery vehicles, and sensors as well as for gas storage. The physical properties of the resultant mp-Si generated via magnesiothermic reduction, and thus the potential utility, are highly dependent on the specific reduction conditions utilized. Herein, we report a modified magnesiothermic reduction method which allows for the synthesis of high surface area mp-Si nanoparticles. The reaction was initiated at 650 °C and then cooled to a lower temperature to minimize heat-induced morphological damage. The nanoparticles were characterized by using powder X-ray diffraction, scanning and transmission electron microscopies, and N 2 adsorption isotherm measurements. Particles prepared by using two-step annealing with the initial processing condition of 650 °C for 30 min followed by 300 °C for 4 h resulted in crystalline and completely reduced mp-Si with a high specific surface area of 542 ± 18 m 2 /g. mp-Si nanoparticles generated by using these specific parameters were further used for stoichiometric CO 2 conversion to CH 3 OH, and the reaction yields were 2.5 times higher than prior reports, demonstrating usefulness in effecting an important chemical transformation.
Surface modification has been shown to be useful for improving the cycling performance of cathode materials. Typically heterocompositional coatings are applied on cathode particle surfaces using methods, such as aqueous deposition and atomic layer deposition (ALD), that can be expensive and inefficient. In this report, a dry mechanofusion method was used to treat cathode particles with no auxiliary coating applied. This resulted in a drastic reduction in surface area and the elimination of surface features on the particles. Furthermore, the processing results in an iso-compositional amorphous shell on the surface of each particle. The resulting particles have improved cycling. We believe the mechanofusion process is an important step toward the goal of improving the cycling performance of cathode materials.
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