Fe 2 O 3 /FePO 4 /FeOOH Ternary Stepped Energy Band Heterojunction Photoanode with Cascade-Driven Charge Transfer and Enhanced Photoelectrochemical Performance.

Controlling the charge transfer pathway in semiconductors is an important method to improve charge separation efficiency and enhance photoelectrochemical activity. In this work, a Fe 2 O 3 /FePO 4 /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 H 2 and O 2 evolution rates for photoelectrochemical water splitting of Fe 2 O 3 /FePO 4 /FeOOH photoanode are 0.247 and 0.111 μmol min -1 , which is 2.15 and 1.95 times that of the Fe 2 O 3 /FePO 4 photoanode, respectively. The incident photocurrent efficiency (IPCE) of Fe 2 O 3 /FePO 4 /FeOOH photoanode under 365 nm light irradiation is 1.5 and 1.8 times that of Fe 2 O 3 /FePO 4 and Fe 2 O 3 /FeOOH photoanodes, respectively. This work provides an attractive strategy for solar energy conversion to construct efficient photoelectrochemical photoanode materials.