Enhancing hydrogen evolution of MoS_(2) basal planes by combining single-boron catalyst and compressive strain

M0 S2 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 M0 S2 basal surface and achieve high HER activity by combining single-boron catalyst and compressive strain was reported through density functional theory(DFT)computations.The ab initio molecular dynamics(AIMD)simulation on B@MoS2 suggests high thermodynamic and kinetic stability.We found that the rather strong adsorption of hydrogen by B@MoS2 can be alleviated by stress engineering.The optimal stress of -7%can achieve a nearly zero value of △Gh(〜-0.084 eV),which is close to that of the ideal Pt-SACs for HER.The novel HER activity is attributed to(i)the Bdoping brings the active site to the basal plane of M0 S2 and reduces the band-gap,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 SiN/B@MoS2 heterojunction,which introduces an 8.6%compressive stress for B@MoS2 and yields an ideal AGh-This work provides an effective means to achieve high intrinsic HER activity for M0 S2.

TM_(3)(TM=V,Fe,Mo,W)single-cluster catalyst confined on porous BN for electrocatalytic nitrogen reduction

Confined metal clusters as sub-nanometer reactors for electrocatalytic N_(2) reduction reaction(eNRR)have received increasing attention due to the unique metal-metal interaction and higher activity than singleatom catalysts.Herein,the inspiration of the superior capacitance and unique microenvironment with regular surface cavities of the porous boron nitride(p-BN)nanosheets,we systematically studied the catalytic activity for NRR of transition-metal single-clusters in the triplet form(V_(3),Fe_(3),Mo_(3) and W_(3))confined in the surface cavities of the p-BN sheets by spin-polarized density functional theory(DFT)calculations.After a two-step screening strategy,Mo_(3)@p-BN was found to have high catalytic activity and selectivity with a rather low limiting potential(-0.34 V)for the NRR.The anchored Mo_(3) singlecluster can be stably embedded on the surface cavities of the substrate preventing the diffusion of the active Mo atoms.More importantly,the Mo atoms in the Mo_(3) single-cluster would act as“cache”to accelerate electron transfer between active metal centers and nitrogen-containing intermediates via the intimate Mo-Mo interactions.The cooperation of Mo atoms can also provide a large number of occupied and unoccupied d orbitals to make the"donation-backdonation"mechanism more effective.This work not only provides a quite promising electrocatalyst for NRR,but also brings new insights into the rational design of triple-atom NRR catalysts.