Non-noble Metal Catalysts And Gel Electrolytes For Water Electrolysis

Since the industrial revolution,the progress of technology has brought convenience to human life,but also caused serious environmental pollution and excessive consumption of fossil energy.Therefore,the development of green,environmentally friendly and sustainable energy has become a top priority.Because of its non-polluting,renewable and high energy density,hydrogen energy is increasingly valued by many countries.However,the cost of hydrogen production is still high at present.In addition to the high cost of electricity,the cost also comes from the use of noble metal catalysts and the difficulty of mass transfer in liquid-phase reaction and the reduction of effective area leading to the energy consumption increased.Therefore,it is of great significance to develop low-cost and efficient hydrogen production technology of water electrolysis.In this paper,a simple and effective preparation method is developed to synthesize non-noble metal catalysts as electrode materials,and the gel electrolyte electrochemical cell is designed as the reaction device of water electrolysis to achieve the above goals.The specific research is as follows:1.A Ni-Fe-Sn coating was synthesised in-situ on Ni mesh through one-step electrodeposition at different times.The Ni-Fe-Sn60 electrode obtained after an hour deposition displayed a cauliflower-like morphology,containing numerous spheres ranging from 500 to 700nm melted together.The Ni-Fe-Sn60 electrode exhibited the best electrocatalytic properties for the hydrogen evolution reaction（HER）compared to other electrodes.The electrode required overpotential of 43 and 120 m V at current densities of 10 and 100 m A cm^-2,and a small Tafel slope of 70 m V dec^-1 in a 1 M KOH solution.In addition,the electrode showed outstanding stability in prolonged electrolysis and overall water splitting performance,generating a current density of 93 m A cm^-2 at 1.8 V,which is triple that of an industry electrode.This electrocatalytic activity is ascribed to the high active surface area produced by the cauliflower-like Ni-Fe-Sn particles and the synergistic interaction of Ni,Fe and Sn.The electrode has the advantages of simple synthesis,excellent performance and application prospect.2.The metal-modified Ni Fe（OH）_x nanosheets were rapidly deposited under strong cathodic polarization.The Ni Fe（OH）_x electrode was prepared in the mixture of 0.15 M Ni（NO₃）₂ and 0.15 M Fe SO₄ at a current density of 500 m A cm^-2 for 6 s.The petal like structures formed by interlaced Ni Fe（OH）_x nanosheets can provide convenient path for mass transfer and gas formation,and the conductivity of electrode can be improved after metal modification.The electrode required overpotential of 237 and 263 m V at current densities of10 and 100 m A cm^-2,and a small Tafel slope of 37 m V dec^-1 in a 1 M KOH solution.In addition,the electrode showed outstanding stability in prolonged electrolysis and overall water splitting performance,generating a current density of 50 m A cm^-2 at 1.8 V,which is 1.7 times that of Ni mesh.The preparation of the Ni Fe（OH）_x greatly simplifies the synthesis process of the electrode,and provides a new idea for the preparation of high-performance electrode.3.A series of PAAS-KOH-H2O gel electrolytes with different ratios were synthesized.The ratio of the components at the highest conductivity（PAAS:KOH:H₂O=1:2.5:7.5）was determined by AC impedance method and the highest conductivity is 300.4 m S cm^-1.When the Ni-Fe-Sn60 electrode and Ni Fe（OH）_x electrode were used in the device,the performance was further improved than that in KOH solution.The current density reached 141 and 236 m A cm^-2at 1.7 and 1.8 V cell voltage,which leaded to a 40%and 35%improvement than that of KOH solution.This is due to the fuel cell-type structure of the electrolyzed water device,the high conductivity of the gel electrolyte and the gas diffusion electrode in the device to enhance the mass transfer process.Because the gas diffusion electrode allows bubbles to quickly escape from the electrode surface,avoiding the problem of reducing the reaction area caused by the bubbles covering the electrode.