Preparation And Electrocatalytic Hydrogen Evolution Properties Of Carbon Nanofibers Decorated With Nanocrystals Mateirals

Hydrogen has long been viewed as an important clean energy carrier,and the cleanest way to make it is water splitting into hydrogen and oxygen.In order to reduce the energy cost of the water splitting reaction,suitable catalysts are needed to overcome the energy barrier inherent to this reaction.However,the most active catalysts currently are Pt-based materials for hydrogen evolution reaction（HER）—an important half reaction of the water splitting reaction.Although these noble metal-based materials are highly efficient,they are too expensive and scarce for widespread use in hydrogen production.Therefore,we need to search alternative non-Pt catalysts based on earthabundant elements that possess good catalytic activity and high catalytic stability for HER.However,the tendency of nanocrystals to aggregate/agglomerate often compromises the materials’ overall catalytic activity to a certain extent.Thus,to make full use of a nanocatalyst or to maximize the number of exposed active sites of every nanocatalytic unit of a nanocatalyst,it is very appealing but challenging to avoid any possible aggregation/agglomeration of its nanocatalytic units during synthesis or operation.In addition,the conductivity is also a key factor affecting the overall activity of the material.Therefore,it is also important to improve the conductivity of the catalyst while synthesizing the nanomaterials.Herein,this paper presents a novel confinement strategy to prepare highly dispersed CoS₂ nano-octahedral and CoSe₂ nanoparticles on porous carbon nanofibers,so as to maximize the number of exposed active sites of every nanocatalytic unit.In particular,we prepared well-dispersed octahedral CoS₂ nanocrystals supported on a carbon fiber network through in situ sulfidization or selenylation of the carbon fibre-wrapped Co nanoparticles.The resulting materials,denoted as CoS₂-CFN and CoSe₂-CFN respectively,can serve as highly efficient,stable,non-noble metal electrocatalysts for HER,even when the loading amount of the catalytically active phase CoS₂ and CoSe₂ are only ⁰.053 mg cm-2 and ⁰.28 mg cm-2,the value much lower than that for their previously reported materials.Their excellent catalytic properties benefit from the collective effects of the intrinsic catalytic ability of materials,the well-dispersed nanocrystals,as well as the high conductivity and porous structure of the carbon fibre network as a support material.