Porous edge confinement: High carrier potential and low activation energy barrier synergistically boosting the efficiency of selective photocatalytic CO2 conversion

Abstract

Catalysts which allow directional transfer of photogenerated electrons to catalytic sites are crucial to efficient photocatalytic CO2 reduction. Herein, 2D BiOCl porous nanosheets (BOC-PNS) are prepared by triblock polymer (F127) assisted mechanical ball milling. The main exposed plane is (001) on the BOC-PNS surface and the porous structure increases the edge (110) facet. The (001)/(110) heterojunction enhances directional migration and separation of photogenerated carriers. In situ Raman scattering, in situ Fourier transform infrared spectroscopy, 3D FDTD simulation and theoretical calculations reveal that the BOC (001) plane is enriched with directionally migrating photogenerated electrons and provides the primary active sites to bridge adsorption-activated CO2 molecules consequently producing a smaller energy barrier for the intermediate product of *COOH. Weak CO adsorption on the BOC (001) plane further promotes CO2 reduction. Upon exposure to simulated sunlight, the CO yield of BOC-PNS is enhanced by the rich edge confinement effect reaching 28.2 μmol g−1 h−1, which is 2.1 and 2.8 times that of the BOC nanosheets (13.5 μmol g−1 h−1) and nanoplates (9.9 μmol g−1 h−1), respectively.