Construction Of Descriptor And Volcano Realationship For Nitrogen Reduction Reaction And Other Electrocatalytic Reactions

The development of electrochemical ammonia synthesis technology at room temperature and pressure is essential,given the high energy consumption and the generation of polluting gases in the Haber-Bosch（H-B）process.However,the electrochemical synthesis of ammonia still faces serious challenges such as low ammonia generation rate and low Faraday efficiency.Therefore,it is imperative to find catalysts with high electrochemical nitrogen reduction（NRR）intrinsic activity and low electrochemical hydrogen elution（HER）intrinsic activity.Recently,transition metal single-atom catalysts（SACs）have been widely used in the electrochemical synthesis of ammonia,yet only a few theoretical computational studies on the electrochemical synthesis of ammonia on such catalysts have been carried out.To this end,a total of 34transition metal single-atom catalysts have been constructed,potential catalysts for electrochemical ammonia synthesis have been screened using DFT theoretical calculations,and volcanic relationships based on energy span models and microkinetic models have been constructed in order to provide some reference for future experiments on electrochemical ammonia synthesis and theoretical calculations.In addition,with the rapid development of computer technology,high-throughput calculations are widely used in the search for structure-activity relationship.In this paper,the high-throughput calculations are used to briefly explore the structure-activity relationship of hydrogen adsorption on metal surfaces,which provides some reference for more in-depth exploration of structure-activity relationship in the future.The work of this thesis is summarized as follows.1.Computational screening of effcient catalysts based on transition metal nitrogen carbon（TM-N-C）for nitrogen electroreductionThe electrochemical NRR on seven transition metals Co,Fe,Nb,Re,Ru,V,and W were probed using DFT to embed graphite in five different ways,for a total of 34（Fe@Zig-4 was failure）single-atom catalysts.By using the computational hydrogen electrode method and the maximum energy barrier model proposed by Norskov et al,it was predicted that most of the structure of the metal Ru and Co@Basal-3 and Fe@Basal-3 have the potential to become catalysts for the electrochemical synthesis of ammonia,considering the competitive reaction of hydrogen precipitation.In addition,a new descriptor is proposed that is more suitable than the traditional descriptor（35）E_*N to describe the nitrogen reduction reaction with a associative mechanism.Finally,by combining the BEP relationship in electrochemistry and the Curtin-Hammett theory,it is obtained that the NRR reaction mechanism in the region near the apex of the thermodynamic volcanic relationship is all Distal*,which means that the reaction mechanism of the electrochemical NRR on the TM-N-C single-atom catalyst can be roughly considered Distal*.2.Correction of traditional volcanic relationsThe prediction of the order of activity of the catalysts near the volcanic top is purely in error due to（35）Gmax model.Based on the computational data in the previous section,this paper uses the Energetic span model and the Micro-kinetics model to obtain the corresponding volcanic relationships.It is found that at low potentials,the volcanic tops do not change with potential and their positions are consistent with the volcanic tops based on the maximum energy barrier model;at high potentials,the volcanic tops show potential dependence as they change with potential.Further exploring,the reason for the above is that at low potentials the rate determination step is a single step,and at high potentials there is no single determination step but a multi-step reaction to jointly control the catalytic reaction.In addition,by comparing the results of the Energetic span model and the Micro-kinetics model,it was found that the two models yielded essentially identical conclusions,which laterally corroborates the accuracy and utility of the Energetic span model in describing catalytic reactions with multiple intermediates.3.High throughput calculations to investigate structure-activity relationships of adsorbed hydrogen on transition metal surfacesThe automatic generation of metal surface structures and the adsorption of hydrogen atoms on metal surfaces is achieved by using the third-party libraries ASE and Pymatgen in Python,and a large amount of data is obtained by performing DFT theoretical calculations on these structures.The input features and specific expressions of the hydrogen adsorption energy are firstly obtained using some common descriptors as input features and SISSO is used,however,a large root mean square error（RMSE）of the true and predicted values is obtained.So,using the recently popular machine learning algorithm Random Forest,which also uses these descriptors as input features,the RMSE is 0.078 e V,which is a big improvement.In addition,to consider the relationship between the electronic structure and the hydrogen adsorption energy,the d-electron DOS value of the surface metal was used as an input feature,and again using the random forest method,an RMSE of 0.0705 e V was obtained,which is a slight improvement from 0.078 e V.This is followed by the recent method proposed by Goddard III to obtain input characteristics that reflect the surface metal ligand environment,and the random forest method to obtain an RMSE of0.072 e V,which is larger than 0.0705 e V,but the latter one requires a large number of DOS calculations,so this method of Goddard III is clearly more practical and provides a better analytical tool for continuing the search for conformational relationships in the future.4.Theoretical and computational studies on the reduction of oxygen to produce hydrogen peroxide on oxygenated carbonThe collaborators found that oxygenated carbon can effectively catalyze the two-electron reduction of O₂ to H₂O₂,so this chapter obtained the effect of different oxygen-containing functional groups on oxygenated carbon on this catalytic reaction by constructing a thermodynamic volcanic relationship for the two-electron generation of H₂O₂ by O₂ with（35）G*OOH as descriptor.The results show that the functional groups-CHO（edge）,-C-O-C-（body phase）and-COOH（edge）all enhance the activity of O₂two-electron reduction of carbon dioxide in graphite to produce H₂O₂,which theoretically validates the experimental results.