Targeted design of metal defects in photocatalysts helps to realize stable and efficient wastewater treatment. Herein, a novel spinel Cu1-xCo2-yO4-z with bimetal defects is precisely designed by a simple temperature programmed reduction method in hydrogen atmosphere. The co-existence of metallic defects leads to defects distortion forming polarization effect, which can significantly accelerate the separation of photogenerated carriers. By optimizing the band structure, Cu1-xCo2-yO4-z induced in-situ H2O2 production (190 μmol L−1·h−1 with sacrificial agent and 78 μmol L−1·h−1 without sacrificial agent) to boost the generation of hydroxyl radical, and the photodegradation activity was 7.8 and 8.4 times for MB and Cr(VI) as that of CuCo2O4, respectively. Bimetal defects achieve high performance through in-situ production of H2O2 and purification of contaminants, providing novel strategies for the applications of spinel photocatalysts in environmental purification.