Unexpected electro-catalytic activity of the CO reduction reaction on Cr-embedded poly-phthalocyanine realized by strain engineering: a computational study

Abstract

The electrochemical conversion of carbon monoxide (CO) into value-added products is highly promising for carbon utilization and CO removal. Based on previous theoretical studies, we computationally explored the effect of strain engineering on electrocatalysis of the CO reduction reaction (CORR) by two-dimensional (2D) transition metal embedded polyphthalocyanines (MPPcs). By calculating the adsorption energy of CO and the free energies of key intermediates on the MPPcs under uniaxial and biaxial strains, it was revealed that only CrPPc under biaxial strain has the potential to exhibit significant enhancement of the catalytic performance. The free energy diagrams of the CORR catalyzed by CrPPc were plotted under specific biaxial strains, where both the optimal reaction pathway and rate-determining step are found to be evidently changed. What's more, the 5% compressive strain imposed on CrPPc results in an ultra-low limiting potential (U_L = −0.09 V) with high selectivity on CH₄ as the final product, indicating unexpected electro-catalytic activity. Our study clearly elucidates that moderate strain could greatly enhance the electrocatalytic performance of 2D materials in the CORR.