| As one of the ideal energy sources to replace traditional fossil resources,hydrogen energy with high energy density is the most promising renewable resource today,and its rational use is conducive to the realization of carbon peaking and carbon neutrality.Therefore,researchers have conducted a lot of research on hydrogen evolution catalysts,but simply relying on experimental methods cannot quickly and efficiently screen out hydrogen evolution catalysts with excellent comprehensive performance.Fortunately,with the emergence of highperformance computers and the rapid development of computing methods,the selection and design of electrocatalysts can be accelerated by theoretical computing methods,which can well guide the synthesis of experiments,practical applications,and even engineering applications.Based on first-principles calculations,this dissertation studies the effects of a series of double transition metal atom doping engineering,metal and non-metal doping engineering,strain engineering,etc.on the hydrogen evolution reaction of MoS2.From the theoretical perspective of"material genetic engineering",MoS2 material with high-efficient hydrogen evolution reaction are designed,and the method that improves the MoS2 hydrogen evolution reaction is found,which points out the direction for the experimental synthesis of MoS2,and reveals the mechanism of doping engineering,strain engineering and other methods to improve the MoS2 hydrogen evolution reaction.,which provides a theoretical basis for the design and synthesis of subsequent catalysts and engineering applications.The main work is as follows:1.Study of the hydrogen evolution performance on MoS2 by double metal atoms doping engineeringIn this chapter,we improve the the hydrogen evolution performance of MoS2 by double transition metal atom doping engineering.Normally,the active sites of MoS2 are concentrated at the edge and the Tafel reaction barrier is high,resulting in low active site density and high Tafel slope.Combining with previous experimental results and theoretical research,the excessive charge transfer on the S site as adsorbing hydrogen,is attributed to the high Tafel slope.However,the doping of bimetallic atoms synthesized in the existing experiments successfully broke the surface inertness of MoS2.The bimetallic atomic doping engineering reduces the charge transfer on the S site of adsorbed H,which is precisely beneficial to improve the catalytic performance of MoS2.We propose a co-doping project of Co and TM（TM=Ti-Fe,Ni）diatomic.Through theoretical calculations,it is revealed that the high activity derives from the synergistic effect of doping transition metal atoms and Co at the same time,then effectively improving the electrical conductivity,and optimized active sites.In particular,Ti-Co-MoS2（plane）and Ti-Co-MoS2（edge）exhibit |ΔGH|=0.009 eV,which is smaller than the reported ΔGH value of noble metal Pt.This modulation of double transition metal atom doping is universal,and can not only activate the reaction sites of MoS2 in-plane,but also activate the edge activity.This work provides a reliable theoretical study for the subsequent improvement of the catalytic activity and engineering application of MoS2.2.Strain engineering and heteroatom doping engineering to modulate the hydrogen evolution performance of MoS2In this chapter,we propose heteroatom doping（Co and X=B,C,N,P,S co-doping）and strain engineering approaches that to co-activate the inert planar S sites of MoS2.Our results show that the introduction of metal-nonmetal atom co-doping can activate the reaction sites in-plane of MoS2.The co-doped MoS2 emerges a new band gap at the Fermi level,resulting in good electronic conductivity,which is beneficial for the hydrogen evolution process.In a practical range,the catalytic activity can be further optimized and fine-tuned.Under various combinations of co-doping and strains,some excellent results indicate that ΔGH can be near thermally neutral.In particular,optimal conditions（ΔGH≈0 eV）can be achieved by various combinations of doping and strain,e.g.,CCo-MoS2（ΔGH≈0.000 eV）at 1.86%tensile strain,5%compressive strain NCo-MoS2 at 4%（ΔGH=-0.040 eV）,and SeCo-MoS2 at 4%compressive strain（ΔGH=-0.009 eV）.These systems achieve almost ideal catalytic states without applying large strains.Furthermore,we also investigated the origin of the hydrogen adsorption behavior by applying electron descriptors.Our study not only predicts an efficient and tunable catalyst for the hydrogen evolution reaction,but also explores the descriptor between intrinsic electronic properties and catalytic activity,facilitating the atomic design of efficient electrocatalysts.3.Transition metal atom and non-metal atom adsorpting engineering to enhance the hydrogen evolution performance of MoS2By anchoring metals（TM=Sc-Ni）and non-metals（X=B,C,N,O,P,Se,Te,S）,the inplane activity of MoS2 can be triggered without applying external force.Based on DFT calculations,we found that MoS2 is a very promising electrocatalyst for hydrogen evolution reaction via metal-nonmetal adsorpting,with good tunability and high activity,comparable to Pt-based catalyst.Compared with previous single-atom catalysts where the supported atoms are easy to aggregate,we propose to adsorb a non-metal atom on the TM,which can not only effectively prevent the aggregation of metal atoms,but also activate the inert MoS2.The anchored MoS2 arises a new band gap at the Fermi level,resulting in good electronic conductivity,which is beneficial for the hydrogen evolution process.Under various combinations of metals and non-metals,the ΔGH in some results can be near thermally neutral.In particular,the optimal condition（ΔGH≈-0.03 eV）can be achieved by first anchoring Cr and then adsorbing single atomic P on Cr.These systems almost reach the ideal catalytic state without the application of external force.In this study,new non-platinum catalysts were explored for the application of hydrogen energy.Compared with traditional catalysts,this new type of liming agent has a stronger hydrogen evolution catalytic effect,and the catalytic performance of some catalysts can be comparable to that of Pt. |
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