A gold nanodendrite-decorated layered double hydroxide as a bifunctional electrocatalyst for hydrogen and oxygen evolution reactions in alkaline media

In this work, a gold nanodendrites-CuMgFe layered double hydroxide composite (AuNDs@LDH) was introduced as a bifunctional electrocatalyst for hydrogen and oxygen evolution reactions (HER and OER, respectively) in alkaline media. AuNDs@LDH/GCE was prepared by the coating of the surface of a glassy carbon electrode using the CuMgFe-LDH suspension, and followed by Au electrodeposition. Field emission scanning electron microscopy (FE-SEM) images and energy dispersive X-ray spectroscopy (EDX) analysis showed that nanodendrite-like structures of Au are formed on the LDH film, while Au is electrodeposited as nanoparticles on the GCE (AuNPs/GCE). The performance of the catalysts for HER and OER was investigated using polarization curves, Tafel plots and electrochemical impedance spectroscopy (EIS). AuNDs@LDH/GCE exhibited the lowest onset potential and highest current density in comparison with AuNPs/GCE and LDH@AuNPs/GCE for both the OER and HER. The lower values of Tafel slope and charge transfer resistance indicated that the kinetics of charge transfer for the AuNDs@LDH are faster than those for the other studied electrodes. A durability test was performed using chronopotentiometry method that reveals the highest durability of the AuNDs@LDH for both of the reactions. The synergistic effect of the AuNDs and LDH and the high active surface area of AuNDs could be major parameters for enhanced catalytic performance of the AuNDs@LDH. As a result, this strategy provides a promising approach for the fabrication of highly efficient metal nanostructure-decorated LDHs, which can be used as a catalyst in water electrolyzers.