Photocatalytic hydrogen evolution via water splitting is considered as one of ideal ways to solar energy conversion and storage, however, the low energy conversion efficiency and weak catalyst stability are still two main obstacles to overcome. In our present study, we found hydrogen peroxide formed during water splitting affect deleteriously the hydrogen evolution activity of catalyst due to the occupation of active sites on catalyst. Such a negative effect of hydrogen peroxide on hydrogen generation can be prohibited by introduction of superoxide dismutase (SOD), which is able to decompose the adsorbed hydrogen peroxide. The in-situ synthesized Sn⁴⁺center over SnO photocatalyst can catalytically decompose hydrogen peroxide more efficiently than SOD, and as a result, Sn⁴⁺/SnO photocatalyst exhibited higher activity for over-all water splitting and better stability. By taking advantage of Sn⁴⁺catalytic properties for hydrogen peroxide, the rate of H₂ evolution reached 18.3 μmol·g⁻¹·h⁻¹ and the corresponding AQE of 0.18% at 420nm over Sn⁴⁺/SnO catalyst under visible light irradiation without noble metal loading.