Selective photocatalytic CO 2 reduction to CH 4 over metal-free porous polyimide in the solid-gas mode.

Using a catalyst-free one-pot polycondensation approach, a new donor-acceptor (D-A) based porous polyimide (PeTt-POP) photocatalyst was developed. PeTt-POP produced CH 4 (125.63 ppm g -1 in 6 h) from CO 2 under visible light irradiation in the gas-solid mode without the use of co-catalysts or sacrificial agents. The progress of the reaction and the corresponding intermediate species involved in the CO 2 reduction were identified by operando DRIFTS experiments, from which a plausible reaction mechanism was proposed.