Sulfide@hydroxide core-shell nanostructure via a facile heating-electrodeposition method for enhanced electrochemical and photoelectrochemical water oxidation

Abstract Designing low-cost, easy-fabricated, highly stable and active electrocatalysts for oxygen evolution reaction (OER) is crucial for electrochemical (EC) and solar-driven photoelectrochemical (PEC) water splitting. By using a facile heating-electrodeposition method, here we fabricated a porous but crystalline Fe-doped Ni3S2. A thin porous surface NiFe hydroxide layer (∼10 nm) is then formed through OER-running. By virtue of the core Fe-doped Ni3S2 with good conductivity and the shell NiFe hydroxide surface with good electrocatalytic activity, the core-shell nanostructure on Ni foam exhibits excellent OER activity in 1 M NaOH, needing only 195 mV and 230 mV to deliver 10 and 100 mA/cm2, respectively, much more superior to those of 216 and 259 mV for the sample deposited under normal temperature. The enhanced photo-response of the sulfide@hydroxide core-shell structure was also demonstrated, due to the efficient transfer of photo-generated carriers on the core/shell interface. More interestingly, it shows a good compatibility with Si based photoanode, which exhibits an excellent PEC performance with an onset potential of 0.86 V vs. reversible hydrogen electrode, an applied bias photon-to-current efficiency of 5.5% and a durability for over 120 h under AM 1.5 G 1 sun illumination, outperforming the state-of-the-art Si based photoanodes.