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.