Effect of tantalum doping on the Fe2O3 toward photoelectrochemical water oxidation

Metal doping is an effective method to increase the photogenerated carrier concentration and improve the carrier transport performance of Fe2O3 for photoelectrochemical water oxidation. This work synthesized a series of Ta-doped Fe2O3 nanoparticles on FTO glasses using a hydrothermal-pyrolysis method. The XPS, XRD, and Raman spectra demonstrated that the Ta5+ dopants occupy the Fe3+ sites. The Ta-doped Fe2O3 photoanodes show noticeable improvement in photoelectrochemical water oxidation via enhanced electron separation and transfer competence. Doping Ta into Fe2O3 forces the Fermi level of Fe2O3 to move to the conduction band, leading to the decrease of charge transfer resistance in Fe2O3 and water oxidation on the surface. Moreover, the carrier concentration was increased. Whereas, to maintain the charge neutrality of the system, the Ta doping inhibits the formation of oxygen vacancies, which act as the effective defects. Consequently, 2%Ta-Fe2O3 performed the optimum enhanced photoelectrochemical water oxidation activity.