Synthesis Of MoS₂ Nanosheets With Enhanced Hydrogen Evolution Reaction Performance

A whole range of new physicochemical properties and a wealth of potential applications will presented as the bulk materials are reduced to nanomaterials.In recent years,nanomaterials have made great progress in scientific research and industrial applications.Nanomaterials have large specific surface area and its surface atoms explode many dangling bonds with unsaturated,so its are easy to combine with other atoms and have great chemical activity.Hence,nanomaterials can be used as electrocatalysts and have great application prospects in the electrocatalytic hydrogen evolution reaction(HER).However,it's very important to develop new electrocatalysts with low cost,high activity and high stability for sustainable water decomposition.Among many promising candidate materials,two-dimensional transition-metal dichalcogenides have attracted substantial attention for hydrogen evolution reaction.Because they have high catalytic activity,multiple catalytic active sites and excellent stability.MoS2 has very low free energy of hydrogen adsorption and is very suitable for the electrocatalytic hydrogen evolution reaction.However,it is reported that the MoS2 catalytic activity is hindered by the less number of thermodynamically unstable Mo edges(act as the active sites)and poor conductivity of the catalyst.Many means have been developed and utilized to improve the catalytic performance of MoS2.Doping is a very effective method.P-doped MoS2 nanosheets can increase the interlayer spacing,which is beneficial to the adsorption and release of hydrogen.There is little articles report it.In this work,we demonstrate the successful synthesis of P-doped MoS2 nanosheets on carbon cloths(CC)directly as an integrated electrode and then investigate the effect of phosphorus doping for the corresponding HER processes.The relationship between doping conditions and electrochemical catalytic properties is also investigated to achieve high-performance catalysts based on MoS2 nanosheets with optimal P-doping.Importantly,after optimized gas-phase phosphidation,the obtained catalysts preserve their initial nanosheet morphology but present an apparent improvement in their catalytic activity with a low overpotential of 133 mV to drive the current density of 20 mAcm-2,along with the excellent electrochemical stability.All these results revealed the technological potency of our P-doped MoS2 nanosheets on CC as an integrated electrode for highly efficient hydrogen evolution.It has excellent electrochemical properties in a series of doped MoS2 nanosheets.The study found that the a heterojunction structure between the Pt/Au(or its compound)and MoS2 nanomaterial can significantly improve its conductivity as well as the HER efficiency.Because these metal are precious metals,its not conducive to large-scale industrial production.Based on the original MoS2 nanosheets prepared in the previous experiment,Ni particles with different density were deposited on the surface of MoS2 nanosheets by e-beam evaporation to form a heterojunction between Ni and MoS2 nanosheets in order to improve the efficiency of HER in this work.There is little articles report this similar methods,cIn this work,we have investigated the effect about Ni particles with different density on HER and found the optimal density of Ni particles for HER.Compared with original MoS2 nanosheets,the Tafel slope of MoS2 nanosheets with Ni particles have decreased to 99 mV/dec and the efficiency of HER has been significantly improved.It has excellent electrochemical properties in previous literatures.The study about field effect transistor based liquid gate(FET)have found that gate voltage not only could control the conductance of semiconductors,but also could control the ion concentration.It is also expected to be tuned by the field effect in theory that charge transfer rate and the dynamics of hydrogen adsorption process in HER.In this work,I expect to fabricate back-gate FETs based MoS2 nanosheets and achieve field-effect tuned adsorption dynamics of MoS2 nanosheets for enhanced HER.First,fabricating back-gate FETs based a single GaSb nanowire to explore the process.Au-GaSb nanowires was synthetized by chemical vapor deposition(CVD)technology.which have lay a foundation for achieve field-effect tuned adsorption dynamics of MoS2 nanosheets for enhanced HER and is consistent with previous literatures.