| Hydrogen energy is considered as one of the most promising renewable energy sources,due to its wide source,clean,carbon-free characteristics,and wide application.Hydrogen production from electrolytic water has the characteristics of high purity and is easy to combine with renewable energy（photovoltaic coupling,etc.）,making it the most promising green hydrogen energy supply method in the future.The current barrier of this technology stems from the development of low-cost,and highly active oxygen evolution reaction（OER）catalysts,thus improving the electrocatalytic decomposition of water performance.NiFe-based hydroxides are highly efficient OER catalysts among non-precious metal catalysts,and have been proved to be a real catalytic active substance produced by surface reconfiguration of various oxygen evolution materials.However,the catalysts suffer from poor electrical conductivity,underutilization of active sites,the substrates used are all high-cost materials such as nickel foam,carbon cloth,and carbon paper,and poor resistance to chloride corrosion,making it difficult to show the potential for industrial electrolytic hydrogen production applications.Aiming at the above problems,this paper improves the inherent defects of NiFe-based hydroxide catalysts by introducing conductive substances,and selects industrial inexpensive stainless steel 316L as the support material.A low-cost,high-efficiency,stable,and resistance to chloride corrosion electrolytic water composite catalytic electrode was prepared by modifying NiFe-based catalyst with hydrothermal growth.The OER activity and corrosion resistance of the catalytic electrode in simulated seawater were further studied.In addition,this catalytic electrode is used to develop alkaline electrolytic cell,which is equipped with a self-designed photovoltaic coupling water electrolytic device,to explore the industrial feasibility of photovoltaic electrolytic water based on stainless steel supported NiFe-based composite electrode.The specific works are as follows:（1）Aiming at the problems of poor electrical conductivity and insufficient utilization of active sites in the catalytic process of NiFe-based hydroxides with self-supported hydrotalcite layer structure,the flower-like nickel-iron based nano-sheet catalyst with layered structure was synthesized by in-situ oxidation and hydrothermal method..The results showed that the in situ oxidation method resulted in a tight bonding between nickel foam,NiO and nickel-iron-based hydroxide,which promoted the rapid charge transfer on the electrode surface.The overpotentials of OER and overall water splitting were 196 m V(@10 m A cm-2)and 0.41 V(@10 m A cm-2)respectively,the catalyst also exhibited good stability in simulated seawater.（2）Based on the high price of nickel foam support materials and poor resistance to chlorine corrosion,three kinds of stainless steel（201,304,316L）,which are relatively inexpensive in industry and have electrocatalytic activity.And then,the surface polishing treatment of the best-performing stainless steel was also used to investigate the effect of the presence of a passivation film on the material activity,and the resistance to chlorine corrosion in a simulated seawater electrolyte.It was found that stainless steel 316L has the optimum OER activity,with an overpotential of 300 m V at a current density of 10 m A cm-2.In addition,the destruction of passivation film by polishing can’t enhance the activity of 316L,on the contrary,it will reduce the resistance to chloride corrosion performance.（3）In this work,S-NiFe-LDH/SS composite catalytic electrodes were successfully prepared from cost and industrial application potential by using S element doping to replace NiO generated by in situ oxidation and loading S-doped NiFe-based hydroxide catalyst on the surface of bulk SS 316L substrate.The OER performance was measured in alkaline and simulated seawater electrolytes,respectively,and the anti-chloride corrosion performance of the catalytic material was analyzed in combination with the polarization curves.The results showed that the S-NiFe-LDH/SS catalytic electrode exhibited excellent OER activity and stability in both electrolytes,requiring only 257 m V overpotential to reach a current density of10 m A cm-2 and Tafel slope of 35.17 m V dec-1.It also shows extraordinarily excellent tolerance in simulated seawater and is expected to be used for industrial electrolysis of seawater for hydrogen production.（4）The composite catalytic electrode prepared was used to design a reasonable alkaline electrolyzer,which was mounted on a self-designed photovoltaic coupled electrolytic water device.The electrolytic cell performance and energy efficiency were measured,and the performance of the catalytic electrode and the device were evaluated comprehensively.The device has a starting potential of about 1.60 V and an overpotential of up to 2.42 V at a current density of 100 m A cm-2,with a Faraday efficiency of 99.7%and an electric water efficiency of32.6%.The results show that there is still a great extent for improvement of the device in terms of overpotential and electric water efficiency,and the device effect can be improved by further optimizing the device,reducing the electrolyzer tank pressure,and enhancing the performance of the catalytic electrode. |
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