Lattice oxygen mechanism triggered via stable Ni–O–W for solar-boosted water electrolysis

Developing an alkaline overall water splitting (OWS) photo-electrocatalyst with high structural stability and excellent solar response capability remains a critical challenge. Here, we report a 10 × 10 cm scalable nickel–tungsten polyoxometalate (NiW-POM) on nickel foam (NF) catalyst that exhibits exceptionally structural stability and synergistic photo-electrocatalytic effects, benefiting from Ni–O–W bridging oxygen bonds. In situ Raman/Fourier transform infrared spectroscopy confirms that NiW-POM experiences no change during the oxygen evolution reaction via the Ni–O–W bridging oxygen bonds, since Ni and W undergo electronic rearrangement by increasing the bond length, thereby demonstrating the excellent structural stability of NiW-POM. Five representative sites on the 10 × 10 cm NiW-POM/NF confirm that all sites exhibit highly consistent crystalline phase structures and catalytic activities via stable Ni–O–W bonds. Notably, NiW-POM achieves a high solar-to-hydrogen conversion efficiency of 23.90% and maintains 1 A cm−2 for 1000 h in industrial-scale electrolysis. Density functional theory calculations clarify the dual role of Ni–O–W bonds in (i) reducing the electron density of lattice oxygen near Ni sites and (ii) enhancing Ni–O electrophilicity, thereby preferentially activating the lattice oxygen mechanism. This work establishes a non-reconstructive photo-electrocatalyst design paradigm for solar-boosted OWS in high-current-density conditions, offering a novel and scalable solution for green hydrogen production.