DFT Theoretical Study On Hydrogen Evolution Properties Of Mxene Matrix Heterocomposites

Due to global warming,environmental degradation and future energy depletion issues in recent years,there is an urgent need to find new energy sources that can meet industrial needs.Among many up-to-date energy sources,hydrogen energy has become the focus of attention due to its high energy density,cleanliness,environmental protection,and renewable advantages.However,the efficient production of hydrogen energy still relies on noble metal catalysts such as platinum(Pt),and the search for electrocatalysts with activities close to Pt and low cost for hydrogen evolution reaction has always been the focus of research in the field of hydrogen energy.Although a large number of 2D materials have been tried as catalysts for hydrogen evolution reaction,the results are always flawed in some aspects.In this paper,two-dimensional heterostructures are constructed with several transition metal dichalcogenides(TMDs)based on the excellent performance of MXene materials,and these heterostructures are simulated and calculated using the first-principles calculation method based on density functional theory.stability and HER electrocatalytic activity,the results show that:(1)After the MXene whose transition metal atoms are Zr and Hf forms a van der Waals heterostructure with CrS2 and NbS2,the structural stability is good,and the HER electrocatalytic activity of MXene/Nb S2 is very high.Electronic structure calculations show that the O functional group on the surface of MXene/NbS2 has more valence electrons than MXene/CrS2,which is the reason for the better activity of MXene/NbS2 than MXene/CrS2.(2)The asymmetric heterostructure formed by MXene and WS2 whose transition metal atoms are Zr,Ti,Hf has stronger structural stability than the van der Waals heterostructure.The calculation results of local charge density show that the transition metal atoms and The S atoms are bonded together;MXene/WS2 has better HER activity than the original MXene,among which Ti2CO/WS2 and Zr2CO/WS2 have very high HER electrocatalytic activities;Low Volmer-Tafel reaction energy barrier.Electronic structure analysis shows that both MXene/WS2 have good electrical conductivity,and the O functional group in the case of adsorbing H atoms has more valence electron charge than the original MXene,and it is easier to adsorb H atoms.(3)The asymmetric heterostructure formed by MXene and VS2 with transition metal atoms of Mo,V,Nb,Zr,Ti,Hf has a similar interlayer bonding situation as MXene/WS2,and has good structural stability;except that the transition metal is Nb MXene/VS2 and other MXene/VS2 can be used as excellent HER electrocatalysts,among which Zr2CO/VS2 has the best activity,with ΔGH reaching 0.025 eV.Electronic structure calculations show that MXene/VS2 are both metallic,and the surface oxygen functional groups have higher valence electron charges than the original MXene;transition state calculations show that Ti2CO/WS2 has a Volmer-Tafel reaction energy barrier of 1.27 eV.