Hierarchically ordered microporous Ag2S QDs-CoOx/NC nanostructures for enhancing photocatalytic CO2 reduction to chemical fuels.

[Display omitted] • A novel 3DOM Ag 2 S-CoO x /NC had been developed by integrating ultrafine Ag 2 S QDs on the surface of 3DOM CoO x /NC. • The 3DOM Ag 2 S-CoO x /NC composite exhibited remarkable performances for the photocatalytic conversion of CO 2 and H 2 O vapor to fuels. • There were dual Z-scheme charge transfer pathways in the 3DOM Ag 2 S-CoO x /NC. • The key role of Ag 2 S QDs was served as an auxiliary to improve the electronic structure and facilitate adsorption/activation capacity of CO 2 and H 2 O. • The multiple photocatalytic mechanisms of CO 2 reduction were further identified by in situ DRIFTS. Rational design of advanced architectural photocatalysts with efficient separation and transfer of photoinduced charge carriers, and well solar light absorption ability is of critical significance for solar energy utilization and CO 2 -to-fuel conversion. Herein, a novel three-dimensional (3D) ordered hollow-wall hybrid composite (3DOM Ag 2 S-CoO x /NC) has been developed by integrating ultrafine Ag 2 S quantum dots (QDs) on the surface of metal–organic frameworks (MOFs)-derived hierarchically ordered macroporous nitrogen-doped carbon skeletons with implanted CoO x nanoclusters (3DOM CoO x /NC). Compared with pristine 3DOM CoO x /NC and traditional ZIF-67-derived CoO x /NC, the constructed 3DOM Ag 2 S-CoO x /NC composite exhibits remarkable performances toward the photocatalytic conversion of CO 2 and H 2 O vapor without any sacrifice reagents to fuels (CO-66.00 μmol g−1h−1, CH 4 -1.21 μmol g−1h−1 and C 2 H 4 -2.33 μmol g−1h−1) and a higher C 2 H 4 selectivity (16.47%) in the gas–solid system under light irradiation (λ > 420 nm). Impressively, dual Z-scheme charge transfer pathways in the 3DOM Ag 2 S-CoO x /NC can provide good channels for boosting electron transfer and charge separation. Experimental characterizations combined with density functional theory (DFT) calculations further elucidate that the key role of Ag 2 S QDs is served as an auxiliary in the 3DOM Ag 2 S-CoO x /NC catalyst to improve the electronic structure and further facilitate adsorption/activation capacity of CO 2 and H 2 O. Moreover, the multiple photocatalytic mechanisms including related key intermediates and conversion process of CO 2 molecules are further identified by in-situ diffuse reflectance infrared fourier transform spectra (DRIFTS). This innovation provides a novel strategy to design well-designed hierarchically porous hybrid structures for photocatalytic CO 2 reduction to high-value fuels. [ABSTRACT FROM AUTHOR]