An artificial photosynthetic system containing an inorganic semiconductor and a molecular catalyst for photocatalytic water oxidation

Abstract Water oxidation has long been considered to be the bottleneck of the water splitting reaction. Most semiconductor-based photocatalysts show low oxidation activity, mainly because of poor charge separation and transfer. Here, we construct an artificial photosynthetic system for photocatalytic water oxidation using BiVO4 as a photosensitizer and cubic Co complex as the oxygen-evolving catalyst. This system exhibits a high turnover frequency (TOF = 2.0 s−1) for O2 evolution in the presence of NaIO3 as an electron acceptor, with an apparent quantum efficiency (AQE) yield of 4.5% at 420 nm, which is ninefold that of bare BiVO4 (0.5%), but the decomposition of the Co complex leads to decreased photocatalytic activity as time goes on. Spectroscopic studies confirmed an efficient interfacial hole transfer process from the semiconductor to the molecular catalyst. These results may shed light on designing artificial photocatalysts with highly efficient molecular catalysts and suitable semiconductor materials for water oxidation.