Fe₂O₃/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 Fe2O3/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 Fe2O3/FePO4/FeOOH photoanode are 0.247 and 0.111 μmol min−1, which is 2.15 and 1.95 times that of the Fe2O3/FePO4 photoanode, respectively. The incident photocurrent efficiency (IPCE) of Fe2O3/FePO4/FeOOH photoanode under 365 nm light irradiation is 1.5 and 1.8 times that of Fe2O3/FePO4 and Fe2O3/FeOOH photoanodes, respectively. This work provides an attractive strategy for solar energy conversion to construct efficient photoelectrochemical photoanode materials.

Deposition of FeOOH Layer on Ultrathin Hematite Nanoflakes to Promote Photoelectrochemical Water Splitting

“…The FeOOH layer can serve as an oxygen evolution cocatalyst. It could make the photogenerated holes on the valence band of hematite transfer to the FeOOH layer [ 47 , 48 , 49 ], to finish the water oxidation and produce oxygen, which is shown in the inset of Figure 7 . On the other hand, the FeOOH facilitates the suppression of the formation of the surface recombination centers.…”

Boosting the photoelectrochemical water splitting of Fe2O3 by surface-state regulation

“…), morphology control, coupling with narrow bandgap semiconductors (WS 2 , 16 CuO, 17 In 2 O 3 , 18 etc . ), and modification with oxygen evolution catalysts (OECs), such as FeOOH, 19 NiOOH, 20 and Co-Pi. 21 However, the specific changing factors are still worth exploring.…”

The impact of iron–boron electrocatalysts on the charge transport and oxygen evolution reaction of bismuth vanadate photoanodes

“…Suitable semiconductor materials include TiO 2 , 7,8 WO 3 , 9,10 Fe 2 O 3 , 11–14 BiVO 4 , 15–18 Ta 3 N 5 , 19,20 etc . Among them, BiVO 4 , existing in three phases, monoclinic scheelite, tetragonal zircon, and tetragonal scheelite, has been reported as a visible-light-driven semiconductor for PEC water splitting.…”

“…4,5 The research of photoelectrode materials is the key point of PEC cells, because light capture, charge transport and water splitting reactions are carried out using photoelectrodes. 6 Suitable semiconductor materials include TiO 2 , 7,8 WO 3 , 9,10 Fe 2 O 3 , [11][12][13][14] BiVO 4 , [15][16][17][18] Ta 3 N 5 , 19,20 etc. Among them, BiVO 4 , existing in three phases, monoclinic scheelite, tetragonal zircon, and tetragonal scheelite, has been reported as a visiblelight-driven semiconductor for PEC water splitting.…”