Investigations on molybdenum phosphide surfaces for CO2 adsorption and activation

Abstract

The activation of CO 2 molecule over a catalyst surface is an imperative step to tackle the depletion of fossil fuels and global warming effects. Here, we present density functional calculations to explore sensitivity of molybdenum phosphide (MoP) surfaces for this purpose. Despite well documented efficacy of MoP as a catalyst for electrochemical hydrogen evolution, the fundamental understanding of their structural and electronic analysis remains incomplete. We consider four types of surfaces, (001), (100), (101) and (110) that have varied distribution pattern of metal atoms (Mo and P) that allowed us to investigate the role of p anions in CO 2 activation. Various adsorption sites over each surface were taken into account, the CO 2 molecule adsorbed over the hcp site of MoP (001) surface adopted bent geometry with elongation of C-O bond length to 1.31 Å with adsorption energy 1.50 eV. The electron localization plots and charge transfer as computed via Density Derived Electrostatic and Chemical (DDEC6) approach provide significant overlap of 0.75 e charge density between adsorbate and adsorbent. The activated CO 2 is investigated in detail through charge density difference plots, Projected Density of states (PDOS) and red shift in the symmetric and antisymmetric stretching frequency. The study provides conclusive evidence for catalytic potential of MoP(001) surface towards CO 2 activation.