α-Fe2O3/CeO2 S-scheme heterojunction photocatalyst for enhanced photocatalytic H2 evolution

High photo-stability and effective charge separation are pivotal for hydrogen production over the photocatalysts through solar energy. Here mesoporous CeO2 nanorods were hydrothermally synthesized using cetyltrimethyl ammonium bromide and tetrapropylammonium hydroxide as the template to construct the novel S-scheme heterojunction alpha-Fe2O3/CeO2 photocatalyst. The obtained heterojunction Fe2O3/CeO2 photocatalyst exhibited outstanding enhanced H2 evolution under visible illumination. The XRD results indicated that the Fe2O3/CeO2 nanocomposites revealed rhombohedral alpha-Fe2O3 and cubic CeO2 structures without impurities. TEM images revealed the formation of CeO2 nanorods with 400 nm length and 20 nm width decorated with Fe2O3 NPs (10 nm). The optimized S-scheme Fe2O3/CeO2 nanocomposites displayed a superior photocatalytic H2 evolution rate of 2973.2 mu molg- 1h- 1, which was promoted 5.43 folds greater than that of CeO2 nanorods (547.05 mu molg- 1h- 1). The electron transport channels in S-scheme Fe2O3/CeO2 nanocomposites interfacial junctions facilitated the directional migration spatial and separation of photocarriers. The H2 evolution rate over the obtained Fe2O3/ CeO2 photocatalyst was significantly promoted due to its synergistic effect, porous architecture, oxygen vacancies, small particle size and high visible light absorption ability. There was no decrease in the H2 evolution rate after five cycles of photocatalytic H2 evolution, which could verify the durability and stability of the Fe2O3/ CeO2 nanocomposite. The photoluminescence (PL) and electrophotochemical responses were conducted to determine the charge carriers separation rate and understand the photocatalytic mechanism.

Automated summary

In this study, mesoporous CeO2 nanorods were hydrothermally synthesized and a novel S-scheme heterojunction alpha-Fe2O3/CeO2 photocatalyst was constructed. The optimized S-scheme Fe2O3/CeO2 nanocomposites displayed a superior photocatalytic H2 evolution rate of 2973.2 mu molg- 1h- 1, which was 5.43 folds greater than that of CeO2 nanorods. The electron transport channels in S-scheme Fe2O3/CeO2 nanocomposites facilitated the spatial migration and separation of photocarriers. The high H2 evolution rate of the Fe2O3/ CeO2 photocatalyst was attributed to its synergistic effect, porous architecture, oxygen vacancies, small particle size and high visible light absorption ability. The durability and stability of the Fe2O3/ CeO2 nanocomposite were confirmed by the consistent H2 evolution rate after five cycles.