Water splitting is thermodynamically uphill reaction, hence it cannot occur easily, and also highly complicated and challenging reaction in chemistry. in electrocatalytic water splitting, the combination of oxygen and hydrogen evolution reactions produces highly clean and sustainable hydrogen energy and which attracts research communities. Also, fabrication of highly active and low cost materials for water splitting is a major challenge. Therefore, in the present study, γ-fe 2 o 3 nanowires were fabricated from highly available and cost-effective iron plate without any chemical modifications/doping onto the surface of the working electrode with high current density. The fabricated nanowires achieved the current density of 10 mA/cm 2 at 1.88 V vs. RHE with the scan rate of 50 mV/sec. Stability measurements of the fabricated fe 2 o 3 nanowires were monitored up to 3275 sec with the current density of 9.6 mA/cm 2 at a constant potential of 1.7 V vs. RHE and scan rate of 50 mV/sec.
Since the fabrication technique for high-entropy alloy (HEA) nanowires/nanopillars is still in its infancy, neither experimental nor modeling analyses of their cold-welding performance have been reported. Based on insights accumulated in our previous experiments and simulations regarding cold-welded metallic nanowires, in this study, the cold-welding performance of HEA nanowires is probed by atomistic simulations. Among different materials, our simulations reveal that extensively twinned structures are formed in CoCrMnFeNi samples, but not in CoCrCuFeNi or Ni samples. The larger fracture strain in certain HEAs is due to the improved ductility around the fracturing area as well as multiple twinning. Unlike in Ni samples, the fracture strains in HEA samples, regardless of being cuboid or cylindrical, are improved by shrinking the sample size. Among different orientations, the [010]-direction monocrystalline nanowires fail at a strain over 0.6, which is almost double that of the [111] direction. The fracture strains in polycrystalline HEA samples are, on average, larger than those in polycrystalline Ni samples. Furthermore, fracture strains in randomly generated polycrystalline HEA samples are more predictable than those in polycrystalline Ni samples with identical grain configurations. As previously reported, dislocation emission is still a prerequisite to fracture in all cold-welded samples.
In this study, we successfully fabricated a single-crystal Fe2O3 nanowire array based on stress-induced atomic diffusion and used this array as the photoelectrode for solar water splitting. With the surface polishing treatment on the sample surface, the density of the Fe2O3 nanowire array reached up to 28.75 wire µm−2 when heated for 90 min at 600°C. The photocurrent density of the optimized sample was 0.9 mA cm−2 at 1.23 V versus a reversible hydrogen electrode in a three-electrode system under AM 1.5 G illumination. The incident photon-to-electron conversion efficiency was 6.8% at 400 nm.
In this research, we propose a new simple method to fabricate high-density Fe2O3 nanowire arrays for solar water splitting, based on oxidation-assisted stress-induced atomic-diffusion.
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