Optimizing The Catalytic Hydrogen Evolution Performance Of Twodimensional Nanomaterials Based On First-principles Method

To achieve efficient splitting water to produce hydrogen and get rid of the excessive dependence on fossil energy has always been a hot topic in the field of new energy research.However,the splitting water to produce hydrogen needs to overcome a high reaction barrier,which must be carried out with the help of a catalyst.Because of its unique physical properties,two-dimensional nano-materials are widely used in the research of catalytic hydrogen evolution.However,the catalytic activity still needs to be improved before it can be commercialized.Based on first-principles calculations,the hydrogen evolution properties of two-dimensional g-C₃N₄ and MoS₂ was optimized by doping impurity atoms,introducing single-boron catalysts and stress.The details are as follows:(1)Based on first-principles calculations,the co-doping strategy of metalnonmetal(S and K)was reported,which effectively tackle the insufficient oxidation capacity,the high carrier recombination rate and limited sunlight absorption seriously suppress the photocatalytic activity of pure g-C₃N₄.The study found that S-K co-doping not only shifts the band edges downwards to achieve a much large overpotential of ca.0.76 V,but also significantly extends the visible-light absorption threshold of g-C₃N₄.More importantly,the newly established channel between neighboring heptazine units in the doped structure is highly favorable for the separation of charge carriers.Related research results help the design of high-performance visible-light-responsive g-C₃N₄-based photocatalyst for solar water splitting.(2)MoS₂ is a promising candidate for hydrogen evolution reaction(HER),while its active sites are mainly distributed on the edge sites rather than the basal plane sites.Herein,a strategy to overcome the inertness of the MoS₂ basal planes and achieve high HER activity by combining single-boron catalyst and compressive strain was reported through first-principles calculations computations.The ab initio molecular dynamics(AIMD)simulation on B@MoS₂ suggests high thermodynamic and kinetic stability.The optimal stress of-7% can achieve a nearly zero value of ?GH(^-0.084 e V),which is close to that of the ideal Pt-SACs for HER.The novel HER activity is attributed to(i)the B-doping brings the active site to the basal plane of MoS₂ and reduces the bandgap,thereby increasing the conductivity;(ii)the compressive stress regulates the number of charge transfer between(H)-(B)-(MoS₂),weakening the adsorption energy of hydrogen on B@MoS₂.Moreover,we constructed a Si N/B@MoS₂ heterojunction,which introduces an 8.6% compressive stress for B@MoS₂ and yields an ideal ?GH.This work not only achieves the high HER activity of MoS₂,but also provides new ideas for the optimization of two-dimensional electrocatalytic materials.(3)Based on first-principles calculations,this paper further extrapolates the doping elements from B atoms to the entire IIIA-VIIA group elements,hoping to screen out the most promising MoS₂-based catalysts for HER through high-throughput screening.The calculation results show that the doping of main-group elements except chalcogens can improve the activity of the MoS₂ basal plane to a certain extent.The Sdefective MoS₂ monolayer doped with In/Ge atom(In3@MoS₂ and Ge3@MoS₂)show excellent HER performance,and their reaction barrier is even lower than that of commercial Pt/C catalyst.In In3@MoS₂ and Ge3@MoS₂,the In/Ge atoms act as electron donors to increase the unoccupied anti-bonding orbital,which enhances the interaction of In/Ge-H bonding.On the other hand,the unique co-existence of electrondepletion and electron-accumulation regions near In/Ge atoms enables the adsorption of free radical H to be moderate.Moreover,the In/Ge atoms also increase the conductivity of MoS₂,especially the In atom brings a new impurity state near the Fermi level.This work presents a promising strategy for exploiting high-performance MoS₂-based catalysts for HER,and would stimulate more researchers to optimize other twodimensional materials by doping main-group elements for HER.