Electrocatalysts with engaging oxygen evolution reaction (OER) activity with lesser overpotentials are highly desired to have increased cell efficiency. In this work, cobalt selenide catalysts were prepared utilizing both wet-chemical route (CoSe and CoSe-DNA) and hydrothermal route (Co0.85Se-hyd). In wet-chemical route, cobalt selenide is prepared with DNA (CoSe-DNA) and without DNA (CoSe). The morphological results in the wet-chemical route had given a clear picture that, with the assistance of DNA, cobalt selenide had formed as nanochains with particle size below 5 nm, while it agglomerated in the absence of DNA. The morphology was nano networks in the hydrothermally assisted synthesis. These catalysts were analyzed for OER activity in 1 M KOH. The overpotentials required at a current density of 10 mA cm–2 were 352, 382, and 383 mV for Co0.85Se-hyd, CoSe, and CoSe-DNA catalysts, respectively. The Tafel slope value was lowest for Co0.85Se-hyd (65 mV/dec) compared to CoSe-DNA (71 mV/dec) and CoSe (80 mV/dec). The chronoamperometry test was studied for 24 h at a potential of 394 mV for Co0.85Se-hyd and was found to be stable with a smaller decrease in activity. From the OER study, it is clear that Co0.85Se was found to be superior to others. This kind of related study can be useful to design the catalyst with increased efficiency by varying the method of preparation.

Water electrolysis is a field growing rapidly to replace the limited fossil fuels for harvesting energy in future. In searching of non-noble and advanced electrocatalysts for the oxygen evolution reaction (OER), here we highlight a new and advanced catalyst, selenized Cu 3 Sn@Cu foam, with overwhelming activity for OER under both alkaline (1 M KOH) and near-neutral (1 M NaHCO 3 ) conditions. The catalysts were prepared by a double hydrothermal treatment where Cu 3 Sn is first formed which further underwent for second hydrothermal condition for selenization. For comparison, Cu 7 Se 4 @Cu foam was prepared by a hydrothermal treatment under the same protocol. The as-formed Cu 3 Sn@Cu foam, selenized Cu 3 Sn@Cu foam, and Cu 7 Se 4 @Cu foam were utilized as electrocatalysts and showed their potentiality in terms of activity and stability. In 1 M KOH, for attaining the benchmarking current density of 50 mA cm −2 , selenized Cu 3 Sn@Cu foam required a low overpotential of 384 mV and increased charge transfer kinetics with a lower Tafel slope value of 177 mV/dec comparing Cu 3 Sn@Cu foam, Cu 7 Se 4 @Cu foam, and pristine Cu foam. Furthermore, potentiostatic analysis (PSTAT) was carried out for 40 h for selenized Cu 3 Sn@Cu foam and with minimum degradation in activity assured the long-term application for hydrogen generation. Similarly, under neutral condition selenized Cu 3 Sn@Cu foam also delivered better activity trend at higher overpotentials in comparison with others. Therefore, the assistance of both Sn and Se in Cu foam ensured better activity and stability in comparison with only selenized Cu foam. With these possible outcomes, it can also be combined with other active, non-noble elements for enriched hydrogen generation in future.

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Development of low-cost and highly abundant transition metal-based electrocatalysts for oxygen evolution reaction (OER) activity with low overpotential and high stability is desired for the utilization of electrolytic water-splitting cells to generate hydrogen (H2) fuel. The electrocatalytic activity could be further improved with the fabricated catalyst possessing microporous structures. In this study, binder-free hydrogen bubble-assisted electrodeposition of Cu, Ni, and phosphorous over a Cu sheet (CuNiP@Cu sheet) electrode was constructed. Three electrodeposition solutions consisting of 3:1, 1:1, and 1:3 mole ratios of Cu to Ni and 0.50 M sodium hypophosphite were utilized to produce electrodes under a range of electrodeposition potentials from −2.0 to −9.0 V vs Hg/Hg2SO4 so as to control the rate of hydrogen bubble template generation. The optimum performance for the OER in 1.0 M KOH solution was achieved using the electrode [i.e., CuNiP@Cu (1:1)] generated from an electrodeposition solution consisting of 1:1 mole ratio of Cu to Ni at −4.0 V vs Hg/Hg2SO4 for 5–20 min, which demonstrated a low overpotential value of 318 mV to achieve 10 mA/cm2 current density with a Tafel slope of 100 mV/dec. The potentiodynamic studies of the electrode showed minimal change in the overpotential value for the OER even after 786 cycles at a scan rate of 200 mV/s. The stability was also confirmed with the potentiostatic studies in which the electrode was found to be stable for 20 h of the experimental time. The outcomes suggest that low-cost, readily synthesized, and binder-free hydrogen bubble-assisted one-step electrodeposited microporous electrocatalysts hold excellent features toward the OER.

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