Fe2 O3 /FePO4 /FeOOH Ternary Stepped Energy Band Heterojunction Photoanode with Cascade-Driven Charge Transfer and Enhanced Photoelectrochemical Performance.

Abstract

Controlling the charge transfer pathway in semiconductors is an important method to improve charge separation efficiency and enhance photoelectrochemical activity. In this work, a Fe2 O3 /FePO4 /FeOOH nanorod photoanode with stepped energy band structure is prepared by a hydrothermal and water bath method. The charge separation efficiency of the ternary heterojunction is higher than that of the traditional type II heterojunction, which might be due to the efficient cascade charge transfer and separation effect of the ternary stepped energy band heterojunction. The H2 and O2 evolution rates for photoelectrochemical water splitting of Fe2 O3 /FePO4 /FeOOH photoanode are 0.247 and 0.111 μmol min-1 , which is 2.15 and 1.95 times that of the Fe2 O3 /FePO4 photoanode, respectively. The incident photocurrent efficiency (IPCE) of Fe2 O3 /FePO4 /FeOOH photoanode under 365 nm light irradiation is 1.5 and 1.8 times that of Fe2 O3 /FePO4 and Fe2 O3 /FeOOH photoanodes, respectively. This work provides an attractive strategy for solar energy conversion to construct efficient photoelectrochemical photoanode materials.