Boosting oxygen evolution in seawater media at large current density via boron-doped (Ni,Fe)OOH grown on Ni3N nanosheets

Exploiting highly efficient oxygen-evolving electrocatalysts is crucial for hydrogen production through seawater electrolysis. Here, a hierarchical structure of boron-doped (Ni,Fe)OOH grown on Ni3N nanosheets supported on nickel foam [denoted as B-(Ni,Fe)OOH/Ni3N/NF] is fabricated. Benefiting from the formation of abundant active sites and the reduced free energy barrier of the rate-determining step caused by B doping, the obtained B-(Ni,Fe)OOH/Ni3N/NF exhibits extraordinary electrocatalytic activity for oxygen evolution reaction, requiring overpotentials of only 283 mV and 309 mV to achieve a current density of 1000 mA cm−2 in alkaline pure water and seawater media, respectively, as well as superior stability. When driven by a commercial Si solar cell, the electrolyzer using B-(Ni,Fe)OOH/Ni3N/NF as the anode and a previously reported Ru/(Fe,Ni)(OH)2/NF as the cathode can achieve a high current of over 1000 mA in alkaline seawater media. This shows the great potential in applying a photovoltaic-driven electrolyzer toward large-scale hydrogen production in seawater electrolysis.