Multiscale Regulation Of Two-dimensional MoS₂ For Electrocatalytic Hydrogen Evolution

Electrocatalytic splitting of water via renewable energy supply is a carbon-neutral,sustainable green hydrogen production technology.However,most of the catalytic electrodes for hydrogen evolution reaction(HER)are using noble metal catalysts currently,which severely hindered their large-scale application.Two-dimensional molybdenum sulfide(MoS2),with unique electronic and structural properties,has shown excellent catalytic performance in HER and is considered as a potential alternative to noble metal catalysts.However,owing to the low density of edge active sites and easy agglomeration of MoS2 layer to form MoS2 bulk with insufficient mass transport,further optimization of MoS2 is needed to obtain a better HER activity compared to noble metal catalysts.In this dissertation,atomic-and macro-scale regulations in the electron and structure of MoS2 have been conducted for boosting its catalytic performance in acidic HER.Further,density function theory(DFT)calculations have been applied to study the effect of the electronic and structural relulation on their HER catalytic performance and mechanism.The main research contents as following:(1)The regulation of co-confining Co/Se dual-atoms over MoS2 for catalyzing HER.Taking advantage of its tri-layer structure,the Co and Se atoms are doped into the inner-layer and surface of MoS2 respectively to obtain the MoS2 with co-confining Co/Se dual-atoms,which presents a much lower overpotential of 382 mV than that of 671 mV over the Pt/C catalyst at a large current density of 1000 mA cm-2.Meanwhile,it exhibits an excellent long-term stability for more than 360 hours under a large current density of 1000 mA cm-2.Experimental charecterizations combined with DFT calculations demonstrate a synergy between the activating effect of confining Co in the inner layer and the stabilizing effect of confining Se in the surface layer,which promotes the formation of both in-plane and edge active sites,so that the catalyst possesses an excellent activity and stability.(2)Hierarchical porous structural regulation over MoS2 for catalyzing HER.MoS2 with macro-mesoporous structure is synthesized by the dual-template method via modulating the size and ratio of the silicon dual-templates.This hierarchical porous structure significantly improves the active surface area and mass transport of MoS2.Moreover,the using of silicon dual-template increases the curvature and brings a spaceconfined effect during the synthesis of MoS2,which effectively reduces the lateral size of MoS2,and thus increasing the density of active edges.Only 156,249 and 331 mV of overpotential are needed to achieve 10,50 and 100 mA cm-2 of current densities,respectively,over the optimized catalyst,significantly surpassing that over the singleporous structural MoS2.