First-principle Study On Structure Modulation And Electrocatalytic Hydrogen Evolution Reaction Of Transition Metal Doped Mox₂?x=Te,s?

Transition metal sulfide MoX₂?X=Te,S?are considered as the best potential alternative hydrogen evolution reaction catalysts to platinum?Pt?due to its unique physicochemical properties and high efficiency performance for hydrogen evolution reaction.Since the catalytic activities of?MoTe₂,MoS₂?are low because only the edge are active,and a large number of planes are chemically inert.It is of great significance to explore effective methods and strategies to improve the catalytic activity.Therefore,based on the density functional theory calculation,this paper studied the structure,electronic properties and hydrogen evolution reaction of the transition metal atoms doped monolayer MoTe₂,different zinc doping concentrations of Zn doped monolayer MoS₂,and a series of transition metal atoms doped monolayer MoS₂ were studied.We further discussed the influence of doping concentration on the HER performance of these catalysts,which provides an important theoretical reference for the design of efficient transition metal sulfide based catalysts guide.The research conclusion of this paper mainly includes the following three parts:?1?The configuration,electronic structure and electrocatalytic hydrogen evolution performance of different transition metal atoms?TM=Au,Ag,Cu,Ni,Pd,Pt,V,Nb and Ta?doped monolayer MoTe₂ have been investigated.The results showed that after the transition metal atoms doped monolayer MoTe₂,all the transition metal atoms could form stable TM-Te bonds with the adjacent Te atoms.The results of hydrogen adsorption performance showed that H atom bonds with Te atom near the doped metal atom on the surface of MoTe₂.Transition metal atom doped MoTe₂ can significantly improve the hydrogen evolution performance of MoTe₂ based catalyst.In particular,compared with the?G_H of MoTe₂ perfect surface?1.78 eV?,Ag,Au and Pt doped MoTe₂,hydrogen adsorption gibbs free energy?G_H value is significantly reduced,which is-0.06 eV,0.05 eV and 0.10 eV,respectively,close to the?G_H of Pt?-0.09 eV?,showing excellent hydrogen evolution reactivity.The results of the electron structure study shows that the band gap was significantly reduced after the transition metal atom doped monolayer MoTe₂.The TM-nd orbitals appeared near the Fermi energy level,indicating that the doped transition metal could effectively adjust the electronic structure of the MoTe₂.The new Te-5p orbitals appear near the Fermi energy level,which can effectively overlap between the Te-5p orbitals and the H-1s orbitals,thus effectively improving the catalytic performance of monomer MoTe₂.Magnetic moment analysis showed that Au,Ag,Cu,Ni,Pd and Pt doped MoTe₂ surface introduced different degrees of magnetic moments,which were 0.5?b,0.8?b,0.2?b,1.1?b,1.9?b and 1.7?b respectively.?2?The configuration,electronic structure and electrocatalytic hydrogen evolution performance of Zn doped monolayer MoS₂ was studied.The results showed that after Zn doped MoS₂,Zn and the adjacent S atom are form six equal Zn-S bonds,and the Zn atom lost 0.86 e.The results of hydrogen adsorption showed that H atom formed S-H bond with Zn atom to adsorb on the surface of Zn doped MoS₂,compared with the ?G_H of MoS₂ perfect surface?1.89 eV?,?G_H value of Zn doped MoS₂ is-0.09 eV,the Gibbs free energy of atomic H adsorption is greatly reduced and hydrogen evolution activity is significantly improved.The electronic structure analysis shows that new electron states of Zn-3d orbitals and 3p orbitals of S atom adjacent to Zn appear near the Fermi energy level of the system,indicating that Zn doped monomer MoS₂ can effectively regulate the electronic structure of MoS₂ catalytic materials.The new S-3p orbitals appear near the Fermi level can overlap with H-1s orbitals,which can improve the hydrogen adsorption performance of monolayer MoS₂.Furthermore,the effect of different Zn doped concentration??=1/16,?=2/16,?=3/16?on the hydrogen adsorption performance was studied.Under different Zn doped concentrations,the Gibbs free energy of atomic H adsorption in the system was all small,indicating that in a wide range of Zn doped concentration,MoS₂ could maintain good hydrogen evolution activity.The results of electronic structure study show that the electronic states of Zn-3d orbitals appear near Fermi level under different Zn doped concentration,which shows that the doped can effectively adjust the electronic structure of the catalyst.?3?A series of transition metal atoms?TM=Ti,Zr,Hf,V,Nb,Ta,Cr,Mo,W,Mn,Re,Fe,Co,Ni,Cu,Zn,Ru,Rh,Pd,Ag,Os,Ir,Pt and Au?doped monolayer MoS₂have been investigated.The results show that the transition metal atoms form TM-S bonds with the S atoms after doped in the MoS₂.The results of hydrogen adsorption showed that 10 kinds of transition metal atoms?Au,Pt,Ag,Pd,Ir,Co,Ni,Zn,Cu,Rh?doped MoS₂ surface could significantly optimize the hydrogen adsorption performance,showing excellent hydrogen evolution reaction performance.The electron structure analysis shows that the effective improvement of hydrogen evolution is attributed to the new bandgap states of transition metals near the Fermi energy level.In addition,we studied the influence of doped concentration on the hydrogen adsorption performance of monolayer MoS₂.The results shows that the 7kinds of transition metal atoms?Zn,Rh,Pd,Ag,Ir,Pt and Au?doped monolayer MoS₂can maintain promote good hydrogen evolution reactivity performance in a wide range of doped concentrations.