Molecular Simulations On The Energy Storage Interface Of Two-dimensional Materials Based On Transition Metal Compounds

Supercapacitors and fuel cells are two main energy storage devices.Electric double layer?EDL?on the solid-liquid interface is one of the main mechanisms of supercapacitors,and hydrogen evolution reaction?HER?that happened on the surface of catalysts is an effective way for hydrogen production.Both the EDL and HER occur at the interface of solid and solution,so an in-depth understanding of the interface contributes much to the improvement of the electric double layer capacitance and HER efficiency.Metallic MoS₂ is a typical transition metal dichalcogenid that has high conductivity and stability.Different interlayer distance could lead to different capacitance and interface structure of MoS₂,while there is no systematically study about it.Co₂P is a common type of transition metal phosphide,which has high HER catalytic activity.Co₂P with different facet may show different HER activity,which is not clear but worthy to analysis it.In this paper,simulations have been used to study the energy storage performance and HER activity of MoS₂ with different interlayer distance and Co₂P with different facet.Molecular dynamics simulations of MoS₂ show that MoS₂ with interlayer distance of1.115 nm has the highest capacitance of 118 F/cm³,and the trend in capacitance is related to that in ionic distribution.Under 4V charging potential,MoS₂ with interlayer distance of1.615 nm has the fastest charging response,which is significantly affected by ionic motin path.This work deeply studied the effects of interlayer distance on energy storage performance of MoS₂,which plays an importance role in the design,synthesis and application of MoS₂ with specific interlayer distance.Density functional theory calculations of Co₂P with different facets found that Co₂P?113?possesses both good surface stability and HER activity,which could be the guidance for catalyst synthesis.Multiple linear regression has been adopted to quantitatively scrutinize the relationship between H-Co bond length distribution and HER activity in the first time,and its mean absolute error is 0.0777 eV.This analysis shows that statistical methods are effective to explore the effect of structure on the HER activity,which could be helpful in understanding the underlying HER mechanism.