Defect-Engineering is a promising way to introduce metal cation vacancies into target materials, thereby resulting in excellent performance for photocatalytic or electrocatalytic water splitting. Inspired by this, we propose an efficient Z-scheme system comprised of 2D MnO₂/Monolayer g-C₃N₄ with defective Mn³⁺ active sites to realize overall water splitting. These defective Mn³⁺ active sites might boost H₂O adsorption and optimize the interfacial charge separation/transfer in the photocatalytic process by introducing the Mn³⁺/Mn⁴⁺ redox couple. As a result, the composite displays an excellent and stable H₂ and O₂ evolution rates of 60.6 and 28.9 μmol g⁻¹ h⁻¹, respectively. Meanwhile, the H₂ evolution rate is up to 28.0 mmol g⁻¹ h⁻¹ with apparent quantum efficiency of 23.33% at 420 nm in the H₂ evolution half reaction. This study provides a new opportunity for constructing a Z-scheme overall water splitting system by exploiting the redox reactions of other metal cation vacancies.

缺陷工程是一种将金属阳离子空位引入目标材料的有前途的方法，从而为光催化或电催化水分解提供了卓越的性能。受此启发，我们提出了一种由2D MnO ₂ /单层gC ₃ N _{4组成的，}具有缺陷Mn ³⁺活性位点的高效Z方案系统，以实现整体水分解。这些有缺陷的Mn ³⁺活性位点可以通过引入Mn ³⁺ / Mn ⁴⁺氧化还原对来增强H ₂ O的吸附并优化光催化过程中的界面电荷分离/转移。结果，该复合材料显示出优异且稳定的H _2。O ₂的释放速率分别为60.6和28.9μmolg ^-1  h ^-1。同时，在H ₂析出半反应中，H ₂析出速率高达28.0 mmol g ^-1  h ^-1，在420 nm处的表观量子效率为23.33％。这项研究为利用其他金属阳离子空位的氧化还原反应构建Z方案整体水分解系统提供了新的机会。