Preparation And Hydrogen Evolution Reaction Properties Of Self-Supported Metal Phosphides Electrodes

As a new type of energy source that has attracted much attention in recent years,hydrogen energy has the advantages of renewable and non-polluting,and has broad development prospects.Hydrogen production by electrolyzing water is a very ideal way to obtain hydrogen.It can convert other intermittent energy sources into hydrogen for storage and meet the requirements of sustainable development.Therefore,developing an efficient and low-cost hydrogen evolution catalyst to reduce the cost is one of the necessary conditions for the promotion of hydrogen evolution by electrolyzing water.The Co-P and Ni-P catalysts were deposited on carbon fiber paper?CFP?by electrodeposition.This method is simple to operate and low in cost,while avoiding the use of binder and improving electron transmission efficiency and the binding force between catalysts and substrate.The surface morphology,elemental composition and elemental valence were analyzed by scanning electron microscopy?SEM?,transmission electron microscopy?TEM?,X-ray diffraction analysis?XRD?,X-ray photoelectron spectroscopy?XPS?,and the hydrophilicity was tested by contact angle tester.Detailed electrochemical tests were carried out and the overpotentials required for Co-P-1/3 to generate current densities of 10 m A cm^-2 and 100 m A cm^-2 in alkaline solution were 61 m V and 201 m V respectively,Tafel slope was 52.6 m V dec^-1,and the performance was close to that of commercial 20%Pt/C.Ni-P-2/1 produced 10 m A cm^-2 and 100 m A cm^-2 current density only required 50 m V and 125 m V,Tafel slope was39.7 m V dec^-1.The catalytic performance was very good in the large current area and even exceeded Pt/C.It also showed excellent stability in the 3000 cycle stability test and the 20 h potentiostatic stability test.These test results show that Co-P and Ni-P catalysts could be used as efficient hydrogen evolution catalysts,especially in alkaline environment,which can provide practical catalysts for environmental hydrogen production.In addition,the crystalline Ni-P was obtained by annealing Ni-P-2/1.The electrochemical properties of crystalline and amorphous Ni-P in acidic and alkaline environment were compared,and the changes of physical properties before and after crystallization state transition were contrasted.Through the calculation of the turnover frequency?TOF?,the change of the inherent catalytic activity was analyzed,and the possible reasons for the difference of hydrogen evolution catalytic activity between crystalline and amorphous Ni-P electrodes were discussed.Due to better hydrophilicity and higher inherent electrocatalytic activity,amorphous Ni-P exhibited excellent performance in alkaline environments,but it was easy to be corroded in acidic solution,resulting in the decrease of catalytic active sites and poor catalytic performance.The inherent catalytic performance and hydrophilicity of crystalline Ni-P was worse than that of amorphous Ni-P,so the catalytic performance in alkaline solution was not as good as that of amorphous.But the crystalline Ni-P showed good stability in acid solution due to its good crystalline structure.