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To convert greenhouse gas CO2 to available energy by using solar energy is a promising approach for addressing energy dilemma and global warming issues. Although CdS as a photocatalyst can achieve CO2 reduction to fuel, there are still two main problems of activity and stability to be solved. Herein, a simple hydrothermal method with the presence of a little quantity of H2O2 is used to prepare CdS with Cd vacancies, which can promote the separation of photogenerated electrons and holes for activity improvement. It is found that the best catalyst 0.4CdS demonstrates not only high CO selectivity over other carbonaceous products, but also a considerable CO production rate of 316 mu mol g(-1) h(-1), which is 2.1 times as high as that of pure CdS for CO2 reduction under visible light irradiation. In addition, an efficient solution through an additional feeble negative voltage to improve the photo stability of 0.4CdS is achieved, which makes this sample remain 94.2% of its original CO2 photoelectrocatalytic reduction performance after four cycles. Thus, this study provides a facile strategy to address the stability and activity issues of CdS under visible light irradiation, which is presumably suitable for improving the other semiconductors with low stability and activity for highly efficient CO2 reduction.