Studies On The Synthesis And Properties Of Self-supportive Electrocatalysts For Electrochemical Water Splitting

With the shortage of fossil energy and people's increasing emphasis on the ecological environment,electrolysis of water to hydrogen as a green,clean and sustainable way of energy utilization,has received more and more attention.Under the continuous research and expansion of the researchers,the energy barrier of water splitting can be reduced by the electrocatalysts,so that the splitting voltage required to be loaded is as close as possible to the theoretical voltage of water splitting.However,the electrocatalysts with the best electrocatalytic performance have their own advantages and disadvantages.For example,noble metal catalysts such as Pt-based and Ru/Ir and their oxides have excellent electrocatalytic properties,but they are rare and expensive.Although some non-noble metal catalysts can approach or even exceed the catalytic performance of noble metal catalysts,the preparation is complex.Moreover,these non-noble metal catalysts are usually in the form of powder,which needs to be bonded to the corresponding carrier by a suitable binder to be used for water splitting.When used at a large current density,a large amount of hydrogen and oxygen are separate out,violent disturbance is generated near the electrode.The catalyst particles are easily detached from the substrate,resulting in a degradation of catalyst performance.Therefore,in this paper,copper foam and 304 stainless steel mesh are taken as case studies to explore the rapid preparation method of functional integrated electrocatalyst,which include both the substrate and the active material,and the following conclusions are drawn through the systematic study:In chapter 3,after etching of copper foam in 1 M NiCl₂·6H₂O solution for 120 s,only an overpotential of 257 mV is needed to provide a current density of 20 mA cm^-2.After 48 hours of potentiostatic polarization under this current density,the current density could still reach over 80%of the initial current.In chapter 4,after treatment of 304 stainless steel in 2 M Ni²⁺boiling solution for 120s,the overpotential at 10mA cm^-2 current density is 214 mV,the Tafel slope is34.84 mV dec^-1 and after 10 h of potentiostatic polarization at 20 mA cm^-2 current density,the catalytic performance barely changed.In chapter 5,the copper foam and 304 stainless steel mesh can be prepared into functional integrated materials with better OER performance by only 120 s treatment in related boiling solution,which is conducive to industrialization and large-scale production.After phosphating the copper foam and 304 stainless steel mesh samples with the best OER performance to improve the HER performance,they are assembled together with the original samples into CF-1M Ni-120s-P//CF-1M Ni-120s and SS-Ni-OH2M-P//SS-Ni-OH2M water splitting device.Only overall voltages of 1.71V and 1.60V are needed respectively to provide 10mA cm-² current density.