Inhibiting competing reactions of iodate/iodide redox mediators by surface modification of photocatalysts to enable Z-scheme overall water splitting

•Surface modification strategy was applied to inhibit the competing reactions enable Z-scheme overall water splitting.•MgO modification on Ta3N5 can suppress the adsorption and oxidation of I− ions as well as promoting the O2-evolving rate.•Surface coating of Cr2O3 on Pt loaded on ZrO2/TaON can inhibit the reduction of IO3− ions and improve the H2-evolving rate.