The Preparation Of Ruthenium-based And Iridium-based Composite Materials And The Study Of Their Electrolytic Water Performance

Energy crisis caused by the shortage of fossil resources seriously threats human survival and development,thus exploring pollution-free and recyclable energy techniques is crucial for fulfilling the sustainable development.Hydrogen is a renewable clean energy which has been considered as an ideal candidate to replace fossil fuel and resolve the energy crisis.Up to now,most of the hydrogen is produced from fossil resource by pyrolyzation of hydrocarbons,which will produce CO₂ and some other carbonaceous species that will lead to some environmental problems.So the green method of hydrogen production has attracted much interest,and the electrochemical water splitting has been found to be an effective and environmentally friendly route.Water splitting is composed of two half reactions:the oxygen evolution reaction?OER,2H₂O?O₂+4H⁺+4e^-?at the anode and the hydrogen evolution reaction?HER,2H⁺+2e^-?H₂?at the cathode.Water splitting can convert electrical energy into chemical energy which store in the hydrogen.However,high overpotential of electrolysis consumes the electrical energy thus results in low efficiency of water splitting.Therefore,designing appropriate electrocatalysts which can reduce the overpotential at anode and cathode is the key for popularizing the water splitting in large scale.In this study,we designed Iridium and Ruthenium based catalysts with optimize structure,high activities for water splitting.Details are listed as follows1.The organic Ir complex as the precursor which underwent pyrolysis on graphene to form the structure of Ir nanoparticles anchored on nitrogen-doped graphene?Ir/NG?with different Ir loading.The physical characterization demonstrated that the organic Ir complex was decomposition and reduction to Ir nanoparticles,and nitrogen was doped into grapheme simultaneously,Ir/NG was formed eventually.The electrochemical results showed that theIr/NG with 11.6 wt%Ir exhibited the best catalytic activites in both HER and OER in acidic and alkaline solution.Moreover,the Ir/NG with 11.6 wt%Ir also presented excellent stabilities during long-term electrolysis.2.A novel Ru/RuO₂ structure which was synthesized by a controllable pyrolysis of Ru³⁺coordinated cyanoguanidine as precursor was presented.The composite can be evolved from Ru/RuO₂ structure to pure RuO₂ via adjusting the pyrolysis temperature from 500 to 800?.Taken the advantage of the Ru/RuO₂ heterostructure,the Ru/RuO₂ structure exhibited much improved OER activity and stability than pure RuO₂ in both acidic and alkaline solution.Especially in acidic solution,Ru/RuO₂structure only exhibited overpotential of 200 mV to reach the current density of 10mA cm^-2,and even maintained stable for more than 24 hours without obvious attenuation.In contrast,the catalytic activity of pure RuO₂ suffered severe recession due to dissolution of RuO₂ at high anodic potential in acidic solution.This study provides a new strategy to solve the bottleneck of OER in acidic solution.