Theoretical Study On The Catalytic Mechanism Of Carbon Dioxide Catalyzed By Metal Corrole

Corroles,as the ring-contracted analogues of porphyrins,are also aromatic macrocyclic systems constructed by the four conjugated pyrrole rings.Similar to metal-porphyrins,metal-corroles exhibit excellent catalytic properties.In order to find excellent catalyst for CO₂ reduction,the catalytic mechanism for metal corroles mediated CO₂ reduction has been investigated by density functional calculations.Firstly,the reduction of CO₂ by H2 to HCOOH catalyzed by Mn-corrole and Cu-corrole in different spin multiplicities has been studied.Calculations demonstrate that quintet state of Mn-corrole is ground state.And the reaction goes through the transition state?TS1?which the H-H bond is cleaved.Then the HCOOH product is obtained.And the whole reaction of CO₂ reduction is carried out in quintet state potential surface.To regulate the reactivity of Mn-corrole,Br atoms are introduced to??2,3?sites.However,the introduction of Br atoms has little effect on the reactivity of Mn-corrole.Similar to Mn-corrole,Cu-corrole mediated CO₂ reduction also go through TS1 to get HCOOH product.Although here are crossings among potential-energy surfaces with different spin states along the reaction pathway catalyzed by Cu-corrole,the reaction of CO₂ reduction is mainly carried out in its ground state.Based on the previous studies,the catalytic mechanisms for metal?Fe,Ag,Au,Pd,Pt and Rh?corroles mediated CO₂ reduction have been investigated by density functional calculated.Calculations demonstrate that the reaction of CO₂ reduction catalyzed by Fe-corrole and Ag-corrole go through TS1 to get HCOOH product,the energy barriers of which are relatively high.However,when Au-corrole,Pd-corrole,Pt-corrole and Rh-corrole are used as catalysts,the reactions of CO₂ reduction go through two steps.In the first step,H-H bond is cleaved.And HCOOH product is got by the H bonding with metal atom transferring to CO₂ in the second step.The energybarriers in the first step are much more than the ones in second stage.The first stage is rate-determining step.The reaction energy barrier is lowest when Rh-corrole used as catalyst,which is a potential excellent catalyst.In addition,we also studied the photocatalytic activity of single-atom Au-doped monolayer graphite phase?Au/g-C₃N₄?,which were studied from the aspects of the electronic band structure,the density of states?DOS?and the partial density of states?PDOS?and bader charge analysis.The results show that the addition of single atom Au to g-C₃N₄ can introduce a new local energy level at the top of valence band of g-C₃N₄,which greatly promotes the migration of photo-generated carriers and enhances the photocatalytic performance of the material.Further investigations on the adsorption of O₂ indicate that O₂ can be activated to super oxygen on the single atom Au of Au/g-C₃N₄ single layer.