Biomimetic (Co, Ni, W)OxNy/WO3 photoelectrocatalyst for robust seawater oxidation

As an intriguing strategy for massive hydrogen production, photoelectrochemical (PEC) seawater splitting compels the anode to be highly hypochlorite-resistant. Inspired by algae, we designed a robust photoelectrocatalyst that WO 3 nanorods (NRs) are covered by N/W co-doped (Co, Ni, W)O x N y nanosheets (NSs). The NSs expose (111) faces and are decorated by (Co, Ni)WO 4 nanoparticles. DFT calculations reveal that Co and Ni atoms on the (111) surface of N/W co-doped NSs are more likely to adsorb OH - , while W atoms are more favorable to adsorb Cl - . Secondly, the lattice distortion and multi-crystal phases of NSs are triggered by doped W atoms, and the evacuation of 5d electrons makes W atoms as donor centers, leading to enhanced catalytic activity of CoNi atoms and corrosion resistance to Cl - . Furthermore, the N atoms expand the valence band of CoNiO x and elevate the conduction band of (Co, Ni)WO 4 , facilitating more electrons to participate in PEC reaction and the realization of seawater full-splitting. Resultantly, the N/W co-doped (Co, Ni, W)O x N y /WO 3 hetero-NRs (HNRs) demonstrate a PEC current density about 0.35 mA/cm 2 at 1.23 V RHE with durability over 100 hours in seawater. This work provides a practical strategy towards the durable PEC anode for seawater splitting.