Theoretical Study On Electrocatalytic Performance Of Transition Metals And Transition-Metal Oxides Described By Bond-Energy-Integrated Coordination Number

Heterogeneous catalysis on transition metal and transition metal-oxides is determined by the chemisorption on the catalytic sites that exhibit distinct catalytic activity and selectivity.Unveiling the nature of chemisorption for different active sites is of crucial importance to unravel catalytic mechanism and design optimal catalysts.However,a simple and efficient theoretical model for describing adsorption property is still lacking,limiting the exploration for identifying active sites.Herein,we presented bond-energy-integrated coordination number for this purpose.This descriptor is simple and effective with high precision which can avoid time-consuming and complex calculations.The specific research results and innovation are as follows:?1?By using moments theorem and linear combination of atomic orbitals?LCAO?model,we build a bond-energy-integrated orbitalwise coordination number as an effective descriptor.This descriptor exhibits a stronger scaling relation with catalysts reaction intermediates in comparison with the usual coordination number?cn?,the generalized coordination number?????,the orbitalwise coordination number(CN),and d-band center theory.The reason for such an excellent descriptor lies in the consideration of the bond energy between the active site and its neighboring sites,as well as the implicit account of the orbital interaction between the adsorbate and surface atoms.From Fermi's golden rule,through an approximation,we reveal the physical nature of bond-energy-integrated orbitalwise coordination number.?2?Bond-energy-integrated orbitalwise coordination number?????,involves the contribution of the bond energy of s-and d-orbitals,which can be used on transition metal-oxides electrocatalysis.According to our theory,-MnO₂ catalyst should exhibit the best oxygen electrocatalytic performance when its??? is at around 5.74.Especially,the theoretical prediction made by the??? descriptor is in good agreement with experimental results,which shows the correctness of the theory.?3?Bond-energy-integrated orbitalwise coordination number?????for transition metal involves the contribution of the bond energy of d-orbitals,which can be used to devise the optimal catalyst for CRR and CMOR.Using this concept,optimal Au catalyst with???=6.1 is devised for CRR with the lowest overpotential?0.3V?.The theoretical prediction made by our model is consistent with experimental results and universal for other heterogeneous catalysis.?4?Bond-energy-integrated orbitalwise coordination number can be unified for performance description in both transition metal and transition metal-oxides.This coordination number can well distinguish surface sites in catalytic activity and selectivity.More importantly,??? is readily extended to other heterogeneous catalysis.This newly identified universal descriptor allows us to gain deep insight into various effects on the catalytic activity including vacancy,strain and different facets.This descriptor provides chances for fast screening and designing optimal catalysts.Therefore,this work paves a new avenue for the development of the theory of heterogeneous catalysis.