Fabrication of mesoporous Cr2O3 with highly distributed α-Fe2O3 and Pt nanoparticles for ultrafast H2 evolution rate

In the present contribution, p-n type heterojunction α-Fe2O3/Cr2O3 S-scheme system photocatalyst has been fabricated utilizing a sol-gel approach with assisted nonionic surfactant for a highly effective H2 evolution rate under visible illumination. Pt NPs have been reduced by photodeposition during the photocatalytic reaction to collect Pt@α-Fe2O3/Cr2O3 finally. XRD analysis of Fe2O3/Cr2O3 nanocomposites verified the construction of Fe2O3 and Cr2O3 with rhombohedral phases. TEM images of Cr2O3 NPs were almost spherical and uniform in shape and size (20 ± 5 nm), and very small Fe2O3 NPs (3-5 nm) were distributed on the mesoporous Cr2O3 networks. The obtained α-Fe2O3/Cr2O3 photocatalyst exhibited noteworthy photocatalytic H2 evolution with high efficiency and stability for 45 h. Interestingly, the photocatalytic H2 evolution rate gradually boosted with the extent of Fe2O3 percentage up to 15% and its rate of 2215.4 μmol g-1h-1, which was fostered 7.25 folds larger than that of Cr2O3 NPs (305.7 μmol g-1h-1). The enhancement H2 evolution rate of Fe2O3/Cr2O3 photocatalyst in comparison with bare Cr2O3 NPs was ascribed to facilitate the separation of photocarriers and existing considerable reactive sites. In addition, constructing n-type Fe2O3 and p-type Cr2O3 with close contact is essential in improving the H2 evolution rate. The possible photocatalytic mechanism over Fe2O3/Cr2O3 nanocomposite was addressed based on electrochemical measurements. The construction of the S-scheme system of Fe2O3/Cr2O3 nanocomposite could be suggested to improve the separation of photocarriers through optimal transfer channels owing to the formation of synergistic characteristics. Our results provide avenues for constructing stable photocatalysts with high efficiency for H2 evolution through visible exposure.