Selective photocatalytic CO2 reduction in aerobic environment by microporous Pd-porphyrin-based polymers coated hollow TiO2

Abstract Direct photocatalytic CO 2 reduction from primary sources, such as flue gas and air, into fuels, is highly desired, but the thermodynamically favored O 2 reduction almost completely impedes this process. Herein, we report on the efficacy of a composite photocatalyst prepared by hyper-crosslinking porphyrin-based polymers on hollow TiO 2 surface and subsequent coordinating with Pd(II). Such composite exhibits high resistance against O 2 inhibition, leading to 12% conversion yield of CO 2 from air after 2-h UV-visible light irradiation. In contrast, the CO 2 reduction over Pd/TiO 2 without the polymer is severely inhibited by the presence of O 2 ( ≥ 0.2 %). This study presents a feasible strategy, building Pd(II) sites into CO 2 -adsorptive polymers on hollow TiO 2 surface, for realizing CO 2 reduction with H 2 O in an aerobic environment by the high CO 2 /O 2 adsorption selectivity of polymers and efficient charge separation for CO 2 reduction and H 2 O oxidation on Pd(II) sites and hollow TiO 2 , respectively.