Modulating the Reaction Configuration by Breaking the Structural Symmetry of Active Sites for Efficient Photocatalytic Reduction of Low-concentration CO2.

Abstract

Photocatalytic conversion of low-concentration CO2 is considered as a promising way to simultaneously mitigate the environmental and energy issues. However, the weak CO2 adsorption and tough CO2 activation process seriously compromise the CO production, due to the chemical inertness of CO2 molecule and the formed fragile metal-C/O bond. Herein, we designed and fabricated oxygen vacancy contained Co3O4 hollow nanoparticles on ordered macroporous N-doped carbon framework (Vo-HCo3O4/OMNC) towards photoreduction of low-concentration CO2. In-situ spectra and ab initio molecular dynamics simulations reveal that the constructed oxygen vacancy is able to break the local structural symmetry of Co-O-Co sites. The formation of asymmetric active site switches the CO2 configuration from a single-site linear model to a multiple-sites bending one with a highly stable configuration, enhancing the binding and structural polarization of CO2 molecules. As a result, Vo-HCo3O4/OMNC shows unprecedent activity in the photocatalytic conversion of low-concentration CO2 (10% CO2/Ar) under laboratory light source or even natural sunlight, affording a syngas yield of 337.8 or 95.2 mmol g-1 h-1, respectively, with an apparent quantum yield up to 4.2%.