Preparation Of Cobalt Phosphide Nanocomposites As An Efficient Water Splitting Catalyst For Hydrogen Evolution Reaction

Recently,the growing demand for clean and sustainable energy sources to alter traditional fuels,hydrogen（H₂）has received growing attention as an ideal energy carrier due to its clean and renewable properties.Electrochemical or photochemical water splitting is considered as an economical and effective way to obtain pure hydrogen.Pt-group noble metal catalysts are the state-of-the-art catalysts which show high performance and excellent stability in H₂ evolution reaction（HER）,but the extensive application for noble based catalysts has been limited by the inherent scarcity.For this reason,it has enormous implications that the investigation of highly active and inexpensive earth-abundant catalysts as Pt substitutes for practical application,for example nitrides,carbides,sulfides and phosphides.Among aforementioned Pt-based alternatives,transition metal-based phosphides（TMPs）have been regarded as one of the most competitive candidate,especially for cobalt based phosphides.Unfortunately,the performance of transition metal-based phosphides still lacks the competitiveness of noble metal catalysts.Meanwhile,the preparation of TMPs has some troublesome processes,such as preparation of precursors,calcinations treatments and generation of toxic gas and so on.Therefore,the approaches of synthesis and improvement the activities of TMPs are urgently needed to perspective for future research.This paper has emphatically study the present development of catalytic water splitting and the synthetic methods of TMPs for HER,as well as the effect of improving TMPs on the hydrogen evolution performance.In this paper,it is proposed that a fast preparation strategy for Co₂P through hydrothermal method within only 3 h for the first time.Meanwhile,it is further analyzed that the effect of photocatalytic hydrogen evolution activity by designing the cobalt based phosphide nanocomposites.It has enormous implications that the preparation of highly active and inexpensive earth-abundant catalysts as Pt substitutes for large-scale water splitting application by a simple pollution-free method.（1）The Co₂P were fabricated by a facile and efficient one-step hydrothermal method.Subsequently,Co₂P with deposited CdS seeds were prepared by a chemical synthesis method in aqueous solution at room temperature.It was reported that this structure of the one-dimensional CdS nanowires deposition on the surface of Co₂P has been obtained via time-dependent experiments for efficient photocatalytic H₂ generation up to now.Meanwhile,a possible enhancement mechanism of CdS/Co₂P photocatalyst nanocomposites for the enhanced H₂-production performance was also discussed.（2）The FeCo₂P/rGO hybrids with controllable rGO composition were directly fabricated by a facile and efficient one-step hydrothermal method.The hydrogen evolution performance and stability of the composite were tested in alkaline environment.It is significant to further promote catalyst performance by involving element doping and grapheme hybridization simultaneously.The single phase cobalt phosphide for alkaline HER has been greatly improved.（3）Ni（OH）₂/Co₂P hybrid catalyst was synthesized by simple and rapid two-step hydrothermal method for fabricating Ni（OH）₂ in situ growth on Co₂P substrates.Firstly,the Co₂P were fabricated by a facile and efficient one-step hydrothermal method.Secondly,Ni（OH）₂/Co₂P hybrids with the input different Ni（OH）₂ content were prepared by one-step hydrothermal method in ethanol solution with Co₂P.Meanwhile,this paper theoretically investigates the mechanism of amorphous Ni（OH）₂with Co₂P nanocomposites toward high activity for catalyzing HER in alkaline electrolytes for the first time.