First-principles calculations on CO2 hydrogenation to formic acid over a metal-doped boron phosphide

Abstract

Converting greenhouse gasses into value-added products are a promising approach to protect the environment. The aim of this work is to design new path which can reduce the use of catalysts for CO2 hydrogenation and further broaden the range of applications of boron phosphide (BP) based materials. The (DFT) was used to investigate the adsorption of H2 and CO2 and their co-adsorption on a transition metal-doped hexagonal BP (M-BP with M = Al, Fe, Co, Ni, Cu, Zn, Pd and Pt). After comparing the binding strength of M-BP to H2 and CO2, Fe-, Co- and Ni-doped BP showed the great potential as catalyst for CO2 hydrogenation. The catalytic mechanism of CO2 hydrogenation reaction was investigated in detail subsequently. It was found that the reaction proceeds through three feasible pathways: (i) path-1 (route A and B starting with the initial co-adsorption of H2 and CO2, where H2 is chemically adsorbed on M-BP, (ii) path-2 starting with the dissociation of H2, (iii) path-3 (route C and D) which starts with the co-adsorption of CO2 and H2, where the CO2 is chemically adsorbed on M-BP. Among them, Fe-BP catalyzed CO2 hydrogenation through path-1 (route B) possesses the smallest energy barrier of (0.19) eV which means that the reaction could be realized at room temperature. Furthermore, in comparison with already reported common CO2 hydrogenation catalysts, Fe-BP can be classified the high quality catalyst with very low energy barrier. These theoretical outcomes might be helpful in the removal and conversion of CO2 into chemical goods with additional value in real-world applications.