Hematite(α-Fe_(2)O_(3))is an ideal oxide semiconductor candidate for photoelectrochemical(PEC)water splitting.Doping of Fe_(2)O_(3)is known to benefit the PEC water oxidation efficiency,but despite extensive research...Hematite(α-Fe_(2)O_(3))is an ideal oxide semiconductor candidate for photoelectrochemical(PEC)water splitting.Doping of Fe_(2)O_(3)is known to benefit the PEC water oxidation efficiency,but despite extensive research efforts,the underlying mechanism still remains elusive.In this work,we report a comprehensive study on the relationship between the electronic structure,interfacial reaction kinetics and PEC activity of Ti-doped Fe_(2)O_(3)photoanodes.The results show that the interfacial charge transfer efficiency at the Fe_(2)O_(3)/electrolyte interface is the main factor in the significant increase of the PEC activity of doped Fe_(2)O_(3).Electrochemical impedance spectroscopy reveals that the interfacial charge transfer efficiency is determined by energy overlap between the water oxidation potential and energy distribution of an intermediate surface state that has been identified as Fe^(IV)=O groups on Fe_(2)O_(3)surface generated during PEC process.Interestingly,the potential energy distribution of this intermediate surface state can be modulated by Ti doping,and a shift towards a more positive potential of the intermediate surface state increases the overlap with the water oxidation potential and thus enhances the kinetics of charge transfer for PEC water splitting.The origin of such potential energy modulation is traced to the inductive effect from Ti-doping on the Fe^(3+)/Fe^(4+)redox transition and the Fe-O bond covalency.Our results provide new insight into the mechanism for the doping effect on the PEC water splitting,introducing new strategies to optimize the PEC activity by tuning the redox properties of active metal oxides.展开更多
基金financially supported by the funding support by the National Natural Science Foundation of China(22021001)funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant agreement No 101030782+1 种基金the RYC2021-034254-I grant funded by MCIN/AEI/10.13039/501100011033 and European Union“Next Generation EU/PRTR”financial support from FJC2020-044866-I/MCIN/AEI/10.13039/501100011033 and European Union“Next Generation EU”/PRTR
文摘Hematite(α-Fe_(2)O_(3))is an ideal oxide semiconductor candidate for photoelectrochemical(PEC)water splitting.Doping of Fe_(2)O_(3)is known to benefit the PEC water oxidation efficiency,but despite extensive research efforts,the underlying mechanism still remains elusive.In this work,we report a comprehensive study on the relationship between the electronic structure,interfacial reaction kinetics and PEC activity of Ti-doped Fe_(2)O_(3)photoanodes.The results show that the interfacial charge transfer efficiency at the Fe_(2)O_(3)/electrolyte interface is the main factor in the significant increase of the PEC activity of doped Fe_(2)O_(3).Electrochemical impedance spectroscopy reveals that the interfacial charge transfer efficiency is determined by energy overlap between the water oxidation potential and energy distribution of an intermediate surface state that has been identified as Fe^(IV)=O groups on Fe_(2)O_(3)surface generated during PEC process.Interestingly,the potential energy distribution of this intermediate surface state can be modulated by Ti doping,and a shift towards a more positive potential of the intermediate surface state increases the overlap with the water oxidation potential and thus enhances the kinetics of charge transfer for PEC water splitting.The origin of such potential energy modulation is traced to the inductive effect from Ti-doping on the Fe^(3+)/Fe^(4+)redox transition and the Fe-O bond covalency.Our results provide new insight into the mechanism for the doping effect on the PEC water splitting,introducing new strategies to optimize the PEC activity by tuning the redox properties of active metal oxides.
