Boosting the Solar Water Oxidation Performance of Fe2O3 Photoanode via Embedding Laser-Generated Pt Nanocrystals

Abstract

α-Fe₂O₃ with suitable band structure, good chemical stability, and easy preparation, is a potential photoanode material. However, the key to enhance the performance of α-Fe₂O₃ photoanode is to improve the transport characteristics of bulk carriers. It is expected to form a Schottky barrier to improve the carrier separation efficiency by embedding metal nanoparticles into the matrix, but the process is still challenging. Herein, a strategy of forming the Schottky barrier is shown to improve bulk carrier transport dynamics by embedding laser-generated Pt nanocrystals in α-Fe₂O₃ photoanode, which achieves photocurrent densities of up to 1.16 mA cm^-2 at 1.23 V_RHE (from original 0.21 mA cm^-2). This work provides another way to promote the carrier transfer and separation of α-Fe₂O₃, which is of great significance to improve the photoelectrochemical water splitting performance.

Keywords: composite Fe2O3@Pt; nanocrystals embedding; nanoporous α‐Fe2O3; photoanodes; photoelectrochemical water splitting.

Figure 1

a) Schematic illustration of Pt nanocrystals generated by PLIL. b) TEM image and c) HRTEM image of Pt nanocrystals. d) Size distribution of Pt nanocrystals (insert: photographs of Pt solution before and after PLIL).

Figure 2

a) Surface SEM images of Fe₂O₃ and b) Fe₂O₃@Pt‐2 films. c) Cross‐section SEM images of Fe₂O₃ and d) Fe₂O₃@Pt‐2 films. e) Optical microscopies of the Fe₂O₃ precursor and f) Fe₂O₃@Pt‐2 precursor. g) TEM and h) HRTEM images of Fe₂O₃@Pt‐2 film.

Figure 3

a) Schematic illustration of Fe₂O₃@Pt films. b) J–V curve of Fe₂O₃ and different Fe₂O₃@Pt films. c) Transient photocurrent measurements of Fe₂O₃ and Fe₂O₃@Pt‐2 films. d) IPCE spectra. e) ABPE spectra. f) Electrochemical impedance spectra (EIS) curves under irradiation of Fe₂O₃ and Fe₂O₃@Pt‐2 film.

Figure 4

a) The calculated current density flux and integrated current density (J _abs) of Fe₂O₃ and Fe₂O₃@ Pt‐2 films. b) Surface charge injection efficiency (η _inj) of Fe₂O₃ and Fe₂O₃@ Pt‐2 films. c) Bulk charge separation efficiency (η _sep) of Fe₂O₃ and Fe₂O₃@ Pt‐2 films. d) Open‐circuit potential of Fe₂O₃ and Fe₂O₃@Pt‐2 films. Schematic diagram of band structures of Fe₂O₃ and Fe₂O₃@Pt‐2 films: e) before and f) after contacting with the electrolytes.

Figure 5

a) TEM image of Au nanocrystals (insert: HRTEM image). b) HRTEM images of Fe₂O₃@Au films. c) J–V curve of Fe₂O₃ and Fe₂O₃@Au films. d) IPCE spectra. e) EIS curves under irradiation of Fe₂O₃ and Fe₂O₃@Au film. f) Open‐circuit potential of Fe₂O₃ and Fe₂O₃@Au films.