title: Improved photoactivity of TiO2-Fe2O3 nanocomposites for visible-light water splitting after phosphate bridging and its mechanism.
abstract: In this work, we have successfully constructed phosphate bridges in a TiO2-Fe2O3 nanocomposite using wet-chemical processes. Based on FTIR, XPS and TEM measurements it is confirmed that phosphate groups form bridges that effectively connect TiO2 and α-Fe2O3. From steady-state surface photovoltage spectra (SS-SPS) and transient-state surface photovoltage (TS-SPV) measurements in N2, it is clearly demonstrated that the separation and lifetime of the photogenerated charge carriers in the TiO2-Fe2O3 nanocomposite are greatly enhanced by the introduction of the phosphate bridges. As a consequence, the visible light photocatalytic activity in water reduction by methanol and the photoelectrochemical water oxidation were obviously improved after phosphate bridging. It is concluded mainly on the basis of ultra-low-temperature EPR signals, EIS spectra, and the normalized photocurrent action spectra that the photogenerated electrons of α-Fe2O3 under irradiation with visible light would transfer to TiO2 in the nanocomposite, and the built phosphate bridges are favorable for charge transportation, leading to the greatly-increased separation and lifetime of visible-light excited charge carriers. This work provides a feasible route to improve the photoactivity of other visible-response nanocomposites for water splitting.
authors.affiliation: Key Laboratory of Functional Inorganic Materials Chemistry (Heilongjiang University), Ministry of Education, School of Chemistry and Materials Science, Harbin, P. R. China. Jinglq@hlju.edu.cn.
authors.forename: Peng
authors.initials: P
authors.lastname: Luan
authors.forename: Mingzheng
authors.initials: M
authors.lastname: Xie
authors.forename: Xuedong
authors.initials: X
authors.lastname: Fu
authors.forename: Yang
authors.initials: Y
authors.lastname: Qu
authors.forename: Xiaojun
authors.initials: X
authors.lastname: Sun
authors.forename: Liqiang
authors.initials: L
authors.lastname: Jing