Preparation Of Binary Ruthenium-Based Catalysts And Electrochemical Hydrogen Evolution Activity

Fossil energy is increasingly depleted,and burning fossil energy can cause enormous damage to the environment.To solve these problems,consider using hydrogen energy as an energy source.In various methods of producing hydrogen energy,electrolysis of water to produce hydrogen is the most effective and does not cause any pollution.Electrolysis of water to produce hydrogen mainly uses the Hydrogen evolution reaction（HER）of the cathode.In order to further improve the efficiency of hydrogen production in electrolysis of water,to study the preparation of an excellent HER catalyst it’s important.Ru is recognized as the best catalyst for Oxygen Evolution Reaction（OER）activity,but its HER study is not much,and its HER activity is also significantly lower than Pt.Therefore,it is a very interesting study to increase the HER activity of Ru and maintain its OER activity to obtain a hydrogen evolution and oxygen double function electrocatalyst.（1）The RuO₂ electrode was prepared by pyrolysis method and heat-treated in an argon atmosphere to obtain a metal Ru catalyst.In alkaline solution,the catalytic activity of HER prepared by pyrolysis of Ru is not only better than that of Ru prepared by hydrothermal method and magnetron sputtering method,but also higher than that of 40%wt Pt/C.At a current density of 10 mA cm^-2,the overpotential of pyrolytic Ru is 88mV,and the Tafel slope is 48.1mV dec^-1,the rate controlling step of the hydrogen evolution reaction is the hydrogen desorption step（Heyrovsky）.In addition,the effects of RuO₂ thermal decomposition temperature and subsequent argon atmosphere heat treatment temperature on the catalytic activity of Ru electrocatalyst HER were also investigated.When the thermal decomposition temperature is 450℃and the Ar atmosphere treatment temperature is 400℃,the Ru electrocatalyst has the best HER activity because of its large electrochemical activity area and preferred growth of Ru（0002）crystal plane.When the current density is 10mA cm^-2,the overpotential required is only 84mV.（2）The RuAlO_x composite oxide was prepared by pyrolysis method.By adding different amounts of Al to prepared different ratios of RuAlOx.They not only have better HER catalytic activity than RuO₂,but also have better OER catalytic activity than RuO₂.The Ru₅₄Al₄₆O_x sample requires only 86mV for the HER overpotential at a current density of 10 mA cm^-2.The initial overpotential of OER is 140mV,which is 5mV lower than the initial overpotential of 145mV of RuO₂,and when the current density is 10mA cm^-2,the overpotential required for oxygen evolution reaction is only 148mV.The Ru₅₄Al₄₆O_x sample’s Tafel slope of the hydrogen evolution reaction is 50.2 mV dec^-1,the rate controlling step of the Volmer-Heyrovsky mechanism,and the hydrogen evolution final step is a composite desorption step.By XPS characterization,the doping of Al caused the RuAlOx composite oxide to produce more low-cost Ru compared with RuO₂,so the RuAlO_x composite oxide catalytic activities of HER and OER were improved.