Gas‐phase photocatalytic coprocessing of CO2 ‐ H2O(v) to energy products promoted by the n,n‐junction In2O3@g‐C3N4 under VIS‐light

Abstract Carbon dioxide capture and utilization is a strategic technology for moving away from fossil‐C. The conversion of CO 2 into fuels demands energy and hydrogen that cannot be sourced from fossil‐C. Co‐processing of CO 2 and water under solar irradiation will have a key role in the long‐term for carbon‐recycling and energy products production. This article discusses the synthesis, characterization and application of the two‐phase composite photocatalyst, In 2 O 3 @g‐C 3 N 4 , formed by thermal condensation of melamine in the presence of indium(III)nitrate. The composite exhibits a n,n ‐heterojunction between two n ‐type semiconductors, g‐C 3 N 4 and In 2 O 3 , leading to a more efficient charge separation. The composite has a flat band potential enabling it to effectively catalyze the reduction of CO 2 in the gas phase to produce CO, CH 4 and CH 3 OH. While the composite‘s overall photocatalytic efficiency is comparable to that of neat g‐C 3 N 4 , its ability to promote multielectron‐transfer and Proton Coupled to Electron Transfer (PCET) suggests that there is a potential for further optimization of its properties. The use of labelled 13 CO 2 has allowed us to clearly exclude that the reduced species are derived from the photocatalyst decomposition or the degradation of contaminants.