Preparation And Electrochemical Performance Of Supported Metal Nanoparticles Electrocatalyst

Metal-supported nanocatalysts have attracted wide attention in electrocatalysis due to their high catalytic activity,selectivity and stability.However,metal nanomaterials,as nanoscale solid particles with high surface energy,tend to lose their excellent physical and chemical properties due to aggregation and passivation.Graphite-carbon material,as a carrier with porous structure,high stability and conductivity,can anchor metal nanoparticles on its surface through element doping,which not only can improve the conductivity of electrocatalysts in multiple levels but also promote the charge transfer ability of the interface between carbon materials and metals.Therefore,in this paper,high-conductivity graphene prepared by shear-assisted supercritical CO₂exfoliation was used as a support,and other support materials were combined with element doping to prepare metal-supported nanoparticle electrocatalysts.The catalysts are used in water splitting,electrocatalytic hydrogen evolution（HER）and electrocatalytic oxygen evolution（OER）.The main contents of this study are as follows:（1）Nitrogen-doped graphene was used as a substrate to prepare nitrogen and phosphorus co-doped graphene-supported metal Co and Ru nanoparticle catalysts based on a simple calcination method and in-situ phosphating method.In addition,the mass ratio of the two metals was adjusted to control the crystal structure of the catalyst.The as-prepared Co:Ru=1:2-P-NG-700 electrocatalyst exhibits excellent HER activity and stability.To reach the catalytic current density of 10 m A cm^-2,it only required 42 m V overpotential for HER,while the corresponding Tafel slope is 63 m V dec^-1.And then a series of characterizations demonstrate that the synergistic effect formed between the（111）crystal plane of CoP and the（001）crystal plane of Ru O₂is the main source of the excellent electrocatalytic hydrogen evolution performance of the electrocatalyst.（2）Nitrogen-doped graphene composite Co-based MOF electrocatalysts were prepared by a one-step high-temperature calcination method.After high-temperature calcination,the metal ligand Co²⁺was reduced to metal cobalt,while the ZIFs retained the original porous framework structure and further composited with nitrogen-doped graphene,thereby providing multi-level electrical conductivity for the catalyst.Results show that the prepared ZIF-NG-700 electrocatalyst exhibits excellent OER performance.ZIF-NG-700 could afford the catalytic current density of 10 m A cm^-2at very low overpotential of 306 m V,while the corresponding Tafel slope is 89 m V dec^-1.In addition,ZIF-NG-700 has both small resistance and excellent stability.（3）Using nitrogen-doped graphene as a substrate,iron-ruthenium bimetallic nanoparticles bifunctional electrocatalysts under different synthesis conditions were successfully synthesized by one-step high-temperature calcination.Experimental results show that the synthesized FeRu-NG-700 exhibited excellent electrocatalytic activity and high stability for both HER and OER in 1 mol L^-1KOH.To reach the catalytic current density of 10 m A cm^-2,it only required 83 m V overpotential for HER and 334 m V overpotential for OER respectively,while the corresponding Tafel slopes are 89 and121 m V dec^-1,respectively.Furthermore,when used as a bifunctional electrode for the full water splitting,an applied voltage of 1.81 V is required for a current density of 10m A cm^-2.The above experimental results provide a new idea for the preparation of high-performance supported nano-metal particle electrocatalysts,and at the same time demonstrate their broad practical application prospects.