Long-term durability of metastable β-Fe2O3 photoanodes in highly corrosive seawater

Durability is one prerequisite for material application. Photoelectrochemical decomposition of seawater is a promising approach to produce clean hydrogen by using solar energy, but it always faces the problem of serious Cl − corrosion. We find that the main deactivation mechanism of the photoanode is oxide surface reconstruction accompanied by the coordination of Cl − during seawater splitting, and the stability of the photoanode can be effectively improved by enhancing the metal-oxygen interaction. Taking the metastable β -Fe 2 O 3 photoanode as an example, Sn added to the lattice can enhance the M–O bonding energy and hinder the transfer of protons to lattice oxygen, thereby inhibiting excessive surface hydration and Cl − coordination. Therefore, the bare Sn/ β -Fe 2 O 3 photoanode delivers a record durability for photoelectrochemical seawater splitting over 3000 h.