摘要：SummaryArtificial photo-driven water oxidation has been proposed over half a century through a four-charge involved multiple-step oxygen evolution process. However, the knowledge of the intrinsic activity, such as the rate-law of the water oxidation reactions, has been inadequately studied. Up to date, the highest order reported is the third one under photoelectrochemical condition. In this work, we identified the fourth-order charge decay reactions on hematite by using a time-resolved surface photovoltage probe technique. A theoretical turnover frequency (TOF) > 100 nm−2·s−1can be expected for O2molecules when the hole density >0.1 nm−2. This work demonstrates a facile and robust method to investigate the high-order reaction kinetics. More excitingly, this research built the bridge between the rate-law, rate-determining step, and energy barrier of intermediates.Graphical abstractDisplay OmittedHighlights•The serial-parallel reaction model is proposed for charge reaction kinetic study•Charge reaction analyzed by the time-resolved surface photovoltage technique•Fourth-order water oxidation is observed on hematite surface•The reaction order depends on the rate-limiting step and the initial intermediatesChemistry; Chemical reaction; Catalysis; Surface chemistry; Materials characterization techniques
