A solar-light double illumination photoelectrocatalytic cell (SLDIPEC) was fabricated for autonomous CO2 reduction and O2 evolution with the aid of photosystem Ⅱ (PS-Ⅱ,an efficient light-driven water-oxidized enzyme from nature) and utilized in a photoanode solution.The proposed SLPEC system was composed of Cu foam as the photoanode and p-Si nanowires (Si-NW) as the photocathode.Under solar irradiation,it exhibited a super-photoelectrocatalytic performance for CO2 conversion to methanol,with a high evolution rate (41.94 mmol/hr),owing to fast electron transfer from PS-Ⅱ to Cu foam.Electrons were subsequently trapped by Si-NW through an extal circuit via bias voltage (0.5 V),and a suitable conduction band potential of Si (-0.6 eV) allowed CO2 to be easily reduced to CH3OH at the photocathode.The constructed Z-scheme between Cu foam and Si-NW can allow the SLDIPEC system to reduce CO2 (8.03 mmol/hr) in the absence of bias voltage.This approach makes full use of the energy band mismatch of the photoanode and photocathode to design a highly efficient device for solving environmental issues and producing clean energy.