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Developing highly efficient catalysts using facile approaches is important for accelerating the slow reaction kinetics of the alkaline hydrogen evolution reaction (HER) and ensuring cost-effective hydrogen production. In this study, we reported a facile alkali etching method to boost the HER activity immediately after electrodeposition of a NiFeZn catalyst on Ti paper. During etching, (oxy)hydroxides were formed on the surface, and Zn species were etched from the deposits, which resulted in a roughened surface with more valleys generated between grains, facilitating a faster mass transport during the electrochemical reaction. The etched catalyst exhibited a boosted HER overpotential of 57 mV at −10 mA/cm2 and accelerated HER kinetic with Tafel slope of 97 mV/dec compared with that of the pristine catalyst. Our results demonstrated an efficient approach for boosting the catalyst activity in the alkaline HER. [Display omitted] • NiFeZn electrocatalysts were prepared on Ti paper using electrodeposition method. • Their morphology and composition were controlled by varying deposition potential. • An alkali etching method is proposed to boost the pristine NiFeZn electrocatalyst. • The defect surface of NiFeZn generated by alkali etching improved HER activity. [ABSTRACT FROM AUTHOR]

To solve the issues of energy shortage and environmental pollution, it is essential to develop highly effective catalysts for hydrogen evolution reaction (HER) in water electrolysis. Herein, we report a facile and rapid fabrication of a Cu–Co–P catalyst on a carbon paper (CP) substrate using electrodeposition. First, the deposition conditions for Co–P/CP were optimized. The prepared Co–P consisted of numerous spheres and exhibited acceptable catalytic activity towards HER in an alkaline medium with an overpotential of 72 mV at current density of −10 mA/cm2. Further performance enhancement was achieved by the incorporation of Cu to modify the electronic structure of the Co–P catalyst. In a half-cell test, the optimized Cu–Co–P/CP exhibits remarkable performance, achieving −10 mA/cm2 at an overpotential of 59 mV, and the Tafel slope is 38 mV/dec. In a single-cell test, an anion exchange membrane water electrolyzer with a Cu–Co–P/CP cathode and commercial IrO 2 /CP anode exhibited high current density of 0.70 A/cm2 at 1.9 V cell. [Display omitted] • Cu–Co–P was electrodeposited on carbon paper while varying the Cu content. • The catalyst shows low overpotential of 59 mV to deliver −10 mA/cm2 and small Tafel slope in 1.0 M KOH. • The Cu–Co–P/CP gas diffusion electrode exhibited high cell performance (0.7 A/cm2 at 1.9 V cell) in AEMWE single cell. [ABSTRACT FROM AUTHOR]

It is important to consider the synergy of heterostructures to improve the slow kinetics of water dissociation in the alkaline hydrogen evolution reaction (HER). Herein, we report a simple method to design a heterohierarchical CoMo catalyst. The CoMo catalyst was prepared by simple one-pot electrodeposition on carbon paper (CP). The CoMo/CP catalyst was optimized for the alkaline HER by controlling the electrodeposition bath conditions, potential, and time. The optimized catalyst shows the heterohierarchical structure containing the electrically conductive metallic Co in the bulk and Mo-incorporated Co containing Mo4+ at the surface. It exhibited a lower HER overpotential of 0.11 V at −20 mA/cm2 compared to those of the others owing to the synergetic effect of the between the Co and Mo incorporated Co. The results highlight the advantages of the simple method developed herein for the design of heterohierarchical catalysts. [Display omitted] • A heterohierarchical CoMo catalyst is fabricated on carbon paper. • The optimized CoMo/CP shows a low HER overpotential of 0.11 V at −20 mA/cm2. • A facile method is proposed to design the heterostructured catalyst. [ABSTRACT FROM AUTHOR]