Integrating the g-C3N4 Nanosheet with B-H Bonding Decorated Metal-Organic Framework for CO2 Activation and Photoreduction.

Abstract

BIF-20, a zeolite-like porous boron imidazolate framework with high density of exposed B-H bonding, is combined with graphitic carbon nitride (g-C3N4) nanosheets via a facile electrostatic self-assembly approach under room temperature, forming an elegant composite BIF-20@g-C3N4 nanosheet. The as-constructed composite preferably captures CO2 and further photoreduces CO2 in high efficiency. The photogenerated excitations from the carbon nitride nanosheet can directionally migrate to B-H bonding, which effectively suppresses electron-hole pair recombination and thus greatly improves the photocatalytic ability. Compared to the g-C3N4 nanosheet, the BIF-20@g-C3N4 nanosheet composite displayed a much-enhanced photocatalytic CO2 reduction activity, which is equal to 9.7-fold enhancements in the CH4 evolution rate (15.524 μmol g-1 h-1) and 9.85-fold improvements in CO generation rate (53.869 μmol g-1 h-1). Density functional theory simulations further prove that the presence of B-H bonding in the composite is favorable for CO2 adhesion and activation in the reaction process. Thus, we believe that the implantation of functional active sites into the porous matrix provides important insights for preparation of a highly efficient photocatalyst.