Enhanced Photocatalytic Carbon Dioxide Reduction to Carbon Monoxide Via 2D g-C3N4 Modifying Homologous Perovskite CsPbBr3/CsPb2Br5 Heterojunction
Abstract
Developing stable and efficient photocatalysts for carbon dioxide (CO2) reduction remains challenging due to the inherent limitations of homologous halide perovskites. While CsPbBr3/CsPb2Br5 heterojunctions exhibit promising band alignment for photocatalytic reactions, their practical application is hindered by the instability of CsPbBr3 quantum dots and the low activity of CsPbBr3. Herein, we propose a modification strategy through the physical recombination of 2D g-C3N4 nanosheets with CsPbBr3/CsPb2Br5 heterojunctions. The constructed type I-II heterojunction architecture establishes dual charge-transfer channels, where g-C3N4 serves as an electron reservoir while the perovskite heterojunction provides CO2 activation sites. Under visible light, the optimized composite achieves a record carbon monoxide (CO) production rate of 28.17 μmol g-1 h-1, representing 4.5 and 4.6 times enhancements over pristine g-C3N4 and CsPbBr3/CsPb2Br5, respectively. Mechanistic studies reveal that the interfacial electric field between g-C3N4 and perovskites prolongs carrier lifetime and reduces the energy barrier for CO desorption (ΔG = -0.54 eV). This study resolves the stability-activity trade-off in perovskite photocatalysts and provides a generalizable paradigm for designing 0D/2D hybrid systems in solar energy conversion.