A halide perovskite based ternary heterojunction with multi-shell hollow structure for stable and efficient artificial photosynthesis

Low-cost halide perovskite materials hold great promise as photocatalysts for CO 2 reduction. However, their inferior water-tolerance will lead to a substantial decline in activity during prolonged photocatalytic CO 2 reduction with water as the electron source. Herein, we integrate a lead-free halide perovskite Cs 3 Bi 2 I 9 as photoactive layer with TiO 2 as water oxidation catalyst and g-C 3 N 4 as CO 2 reduction catalyst to construct a ternary heterojunction (TiO 2 /Cs 3 Bi 2 I 9 /g-C 3 N 4 ) with a multi-shell hollow structure. The formation of heterojunction endows TiO 2 /Cs 3 Bi 2 I 9 /g-C 3 N 4 composite with enhanced photocatalytic activity for CO 2 reduction due to the improved photogenerated carrier separation. TiO 2 /Cs 3 Bi 2 I 9 /g-C 3 N 4 achieves a CO yield of 120.6 μmol g −1 h −1 for photocatalytic CO 2 reduction, which is 3.1 times higher than that of individual Cs 3 Bi 2 I 9 . More importantly, benefitting from the double-sided protection of g-C 3 N 4 and TiO 2 , the photocatalytic CO 2 reduction activity of TiO 2 /Cs 3 Bi 2 I 9 /g-C 3 N 4 remains undiminished even over 100 h of continuous light irradiation, demonstrating significantly improved stability in water-contained reaction system.