Photodeposition fabrication of hierarchical layered Co-doped Ni oxyhydroxide (Ni_xCo_1-xOOH) catalysts with enhanced electrocatalytic performance for oxygen evolution reaction

Highly active, durable and inexpensive oxygen evolution reaction (OER) catalysts are crucial for achieving practical and high-efficiency water splitting. Herein, hierarchical interconnected Ni_xCo_1-xOOH nanosheet arrays supported on TiO₂/Ti substrate have been fabricated through a facile photodeposition method. Compared with pristine NiOOH, the obtained Ni_xCo_1-xOOH nanosheet arrays possess larger exposed electrochemical active surface area, faster transfer and collection of electrons and stronger electronic interaction, showing a low overpotential of 350 mV at a current density of 10 mA·cm^-2 and a small Tafel slope of 41 mV·dec^-1 in basic solutions, with the OER performance superior to pristine NiOOH and most Ni-based catalysts. Furthermore, the Ni_xCo_1-xOOH electrode demonstrates excellent stability at the current density of 10 mA·cm^-2 for 24 hours, which is attributed to the structural maintenance caused by the good adhesion of the catalyst and the substrate. Our study provides an alternative approach for the rational design of highly active and promising OER electrocatalysts.