Electronic modulation and surface reconstruction of cactus-like CoB2O4@FeOOH heterojunctions for synergistically triggering oxygen evolution reactions

Cactus-like heterojunctions with FeOOH nanosheets wrapped on CoB2O4 nanorods/nickel foam-(CoB2O4@FeOOH/NF) were fabricated by a hydrothermal and an electrodeposition strategy for OER processes. Benefiting from the cactus-like architecture for fast mass transfer and more accessible active sites, and strong synergistic effects induced by the formation of Fe-B bond for optimizing electrical conductivity, as well as facilitating the generation of CoOOH unveiled by in situ UV-vis measurement during the OER process, CoB2O4@FeOOH/NF shows superior OER performance with a low overpotential of 255 mV at 100 mA cm(-2), and robust stability for 100 h at 100 mA cm(-2). The two-electrode alkaline electrolyzer (CoB2O4@FeOOH/NF||Pt/C/NF) using CoB2O4@FeOOH/NF as the anode requires a low cell voltage of 1.576 V at 100 mA cm(-2) for driving water splitting, and maintains steadily for 125 h without attenuation at 300 mA cm(-2). This work provides insights into the roles of interfacial engineering by constructing heterojunctions of FeOOH and transition metal borate to design high-performance electrocatalysts for OERs.