All-inorganic perovskite/graphitic carbon nitride composites for CO2 photoreduction into C1 compounds under low concentrations of CO2

CsPbBr3 is widely used in solar cells and LEDs for its excellent photoelectric properties that are also attractive for CO2 photoreduction, but it is less used in the photocatalytic reduction of CO2 mainly owing to its limited charge separation efficiency. To alleviate this issue, herein, all-inorganic orthorhombic CsPbBr3 was combined with graphitic carbon nitride (g-C3N4) and the resultant composite (CsPbBr3@g-C3N4) showed enhanced activity in CO2 photoreduction. Under the irradiation of AM1.5 filter for 12 h, CO2 was converted into CH4 and CO with high selectivity to methane (91%) and the total amount of gaseous products up to ∼300 μmol g-1. This reactivity is 6-fold and 4-fold higher than that of pure g-C3N4 and CsPbBr3, respectively. CsPbBr3@g-C3N4 also shows excellent catalytic activity at low concentrations of CO2. Studies of energy band level and steady-state and transient photoluminescence spectroscopy indicated that the incorporation of CsPbBr3 and g-C3N4 increases charge separation, which may result in sharply enhanced catalytic efficiency. This study has provided opportunities for the combination of CsPbBr3 and other semiconductor catalysts for the photocatalytic reduction of CO2.