Theoretical Study On The Catalyst Design For The Conversion Of CO₂ And CO

Carbon peaking and carbon neutrality goals have become major needs in China and the forefront of world science and technology.How to improve the conversion of carbon dioxide to high-value chemicals has attracted extensive attentions of scientific researchers at home and abroad.Due to the important role of catalysts and their catalytic mechanism in improving the catalytic conversion efficiency,the design and discovery of new materials become an important link to promote related developments.In the benefits of the rapid development of first principles and the continuous breakthrough of computer technology,applying theory and calculation method to systematically design and develop new materials has become possible.Compared with the research process through experimental trial and error,this method will largely improve the efficiency of new material mining,effectively save costs and reduce human investment.Moreover,theory and calculation method lays the foundation for the rapid and efficient design and development of new materials on demand and meeting the increasing demands of industry and experiment for new materials.Thus,combining the principle of computational chemistry and the global optimization algorithm,this paper focuses on the design of materials for CO2/CO catalytic conversions.The details are as follows:1.The design and development of metal-free catalysts used for CO2 reduction is highly challenging.Frustrated Lewis pairs(FLPs)have been considered potential metal-free catalysts for this reaction.However,most FLPs are unstable,which limits their practical applications.In this study,a class of novel metal-free catalysts composed of K3-nHnPO4(n=0,1,2)and B(C6F5-mHm)3(m=0,3,5)were designed.These novel Lewis pairs can be identified as effective catalysts for CO2 hydrogenation to formate by density functional theory calculations.The simulations show that the B-H bond formation is the rate-determining step.The acid(base)strength and repulsive steric interactions affect the corresponding energy barrier.B(C6H5)3KH2PO4 pair with the lowest barrier height show the best performance among these catalysts,is suggested as a promising metal-free catalyst for CO2 hydrogenation.This study may provide help to design new LP-based metal-free catalysts.2.The conversion of carbon monoxide(CO)to valuable multi-carbon chemicals by electro-catalysts is the potential methods to ensure a sustainable carbon cycle.Many catalysts have been designed and developed to achieve efficient conversion.However,research efforts on CO reduction have rarely focused on metal-free catalysts despite them being naturally abundant,non-toxic,environmentally friendly,and possessing a controllable composition.In this paper,a series of nitrogenated graphene(C2N)-based electrocatalysts with heteroatom-doped(B,P,and S atoms)is reported and discussed.Based on the Sabatier theory,the average CO adsorption energy is a key indicator of C-C coupling.The adsorption and ethylene desorption energy are used for the primary screening of various dual-doped catalysts.The stability of the catalysts is used for subsequent screening.It is found that B&P/C2N is suitable for the electro-catalysis.The hydrogenation of the*COCO intermediate is the rate-determining step with a free-energy increase of 0.44 eV.In addition,ethene can easily escape from its surface.This work will assist in the future design of more efficient metal-free catalysts for facilitating the sustainable synthesis of C2H4.3.The morphology of nanocrystals plays a crucial role in determining their physical and chemical properties,such as their catalytic activity.Global optimization methods based on quantum mechanics(QM)have been used to study the morphology of nanocrystals.However,the sizes of the simulated nanocrystals,limited by the computational power,were generally below 0.5 nm.Here,we report an iterative global optimization method(ItGOM),which is capable of globally optimizing gold nanocrystals up to a size of 1.5 nm by combining the iterative QM and molecular mechanics(MM)methods.The QM/MM energy is described by using an effective and simple subtractive approach,and a genetic algorithm technique is developed.In addition,the lower-energy structure of Au13 has been found compared with the previously report.The benchmark simulations of gold nanocrystals reveal that the scheme is efficient in locating the global minimum of nanocrystals.Therefore,this optimization strategy can be used for global optimization and mining the stable conformations of gold nanoclusters.