Monoclinic-rich CsPbBr₃/α-Fe₂O₃S-scheme heterojunction for highly efficient thermal-assisted CO₂photoreduction

A new monoclinic-rich CsPbBr3/porous α-Fe2O3 with 3D/3D heterojunction has been prepared by a facile one-step ligand-assisted reprecipitation (LARP) under low temperature and air atmosphere. The morphologies (i.e., cubic and monoclinic phases) of CsPbBr3 are easily tuned by varying the ratios of precursor solution during the LARP process. We observed that monoclinic-rich CsPbBr3 is favorable to the photocatalytic reduction of CO2 with the superior electron consumption rate of 1.42 mmol g-1 h-1. Upon the heterojunction of monoclinic-rich CsPbBr3 with porous α-Fe2O3, the electron consumption rate is further enhanced to 3.38 mmol g-1 h-1, which is ca. 2.4-fold improvements of pristine monoclinic-rich CsPbBr3. More importantly, the activity can maintain ca. 90% after three consecutive cycles of photocatalytic CO2 reduction. The surpassing performance could be attributed to the higher CO2 uptakes, superior charge separation properties of the CsPbBr3/α-Fe2O3 heterojunction. The apparent activation energies of CO and H2 production calculated by the Arrhenius equation are 26.67 and 31.95 kJ mol-1, respectively. Time-resolved photoluminescence and ultraviolet photoelectron spectroscopy were used to evidence that the S-scheme pathway with an interfacial charge transfer constant of 2.53 × 108 s-1 occurs at the interface of monoclinic-rich CsPbBr3/porous α-Fe2O3. This study demonstrates a very simple wet-chemistry route to synthesize efficient morphology-dependent perovskite/α-Fe2O3 heterojunctions with 3D/3D construction which may provide the promising applications in the solar conversions of CO2.