Pulse-activation engineering induced lattice transformation of layered double hydroxides for efficient alkaline hydrogen evolution

In order to accelerate water dissociation kinetics and improve hydrogen evolution reaction (HER) in alkaline electrolyzer, pulse-activation engineering was proposed to induce lattice transformation of layered double hydroxides (LDHs) electrocatalysts. Physicochemical characterizations and density functional theory (DFT) calculations confirmed that FeOOH crystals diminished with a pulse potential of 1000 cycles (cls) in non-Faradaic region (-0.8~0 V) and transformed into more stable CoFeLDH nanosheet arrays in Fe-rich system. The above transformation effectively reduced H* adsorption energy to accelerate water decomposition for efficient hydrogen evolution reaction. This was because pulse-activation accelerated electron transfer from Co2+ to Fe(3+d)+ through intermittent input negative potential, reducing the high oxidation state of Fe(3+d)+ in FeOOH to generate more stable CoFeLDH. The optimized pulse-activation with CoFeLDH electrocatalyst after 1000 cls decreased the overpotential of alkaline hydrogen evolution by 36%, from 225 mV to 144 mV at-10 mA cm-2. (c) 2022 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.