B₈₀ Fullerene: A Promising Metal-Free Photocatalyst for Efficient Conversion of CO₂ to HCOOH

Abstract

Developing photocatalysts with high efficiency and selectivity for CO2 reduction is essential in the sight of both energy and environment. Through comprehensive density functional theory calculations, we have found that B80 fullerene can be used as an excellent metal-free photocatalyst for reducing CO2 to value-added chemicals in this report. Our results reveal that electron-deficient boron fullerene can effectively activate CO2 (Lewis acid) through Lewis acid–base interactions on the three basic sites of B80 (B80 is an amphoteric molecule). The charge density difference analysis indicates that there are significant charge transfers between CO2 and B80 fullerene on the adsorption sites, which are responsible for the activations of CO2. On the basis of calculating the adsorption energies of the possible products (CO, HCOOH, CH2O, CH3OH, and CH4) on B80 fullerene and the possible reaction pathways producing these products, the B80 fullerene shows high efficiency and selectivity for producing HCOOH. The minimum |Ulim| (0.18 V) of the reaction pathway to produce HCOOH and weaker binding of HCOOH on B80 fullerene (the adsorption energy is −0.51 eV) than the counterparts of CO2 both indicate that the formation and release of HCOOH from the B80 fullerene surface is feasible. In all, our work provides useful information for searching for an excellent metal-free photocatalyst for CO2 reduction.