In addition to the work mentioned above, two research articles in Table and the valence state of active metals affect the yield and stability of OER. Under the irradiation of λ≥ 420 nm, the TON of photodriven water oxidation reaction is 360 when [Co Ⅲ Co Ⅱ (H2O)W11O39] 7-is placed in [Ru(bpy)3] 2+ /Na2S2O8 as photosensitizer/oxidant system. To simulate the oxygen production centre structure of natural photosynthesis, Han X B and colleagues synthesized four Co-POMs, [{Co4(OH)3(PO4)}4(SiW9O34)4] 32-, [{Co4(OH)3(PO4)}4(GeW9O34)4] 32-, [{Co4(OH)3(PO4)}4(PW9O34)4] 28-, and [{Co4(OH)3(PO4)}4(AsW9O34)4] 28-containing Co4O4 cubane structure (Figure ). These four homogeneous catalysts show excellent water oxidation activity, and their structure remains stable in the catalytic process. Meanwhile, the difference in photocatalytic activity of the four clusters can be attributed to the influence of different heteroatoms. The research focus of photo-driven water splitting is to design non-noble metal catalysts with high catalytic activity. Cheap transition metal-modified POMs as multi-electron transfer catalysts have attracted the attention of researchers. The introduction of 3d-metals (such as Mn, Fe, Co, Ni, Cu, etc.) into POMs can adjust the energy gap of POMs-based materials and broaden the absorption spectrum. In conclusion, photocatalytic reactions such as the HER and the OER continue to be attractive research topics due to the increasing demand for environmental improvement and energy transition in countries around the world. In addition, the enhancement of photocatalytic efficiency will be one of the hot topics for POM-based photocatalysts. As, Ge), orange tetrahedra; PO4, yellow tetrahedra; O, red spheres; Co, violet spheres. Reproduced with permission. Copyright 2014, American Chemical Society.