Preparation Of Selenium-based Cobalt/Nickel Catalysts And Their Electrocatalytic Performance

With the shortage of non-renewable energy and the increasingly serious problem of environmental pollution,developing new energy to replace non-renewable energy for production and living is the current research focus.Hydrogen energy is a candidate for new energy because of its advantages of clean and renewable.Among many hydrogen preparation methods,electrolyze water to produce hydrogen has been widely studied for its advantages of environmental protection and simple operation.Therefore,the main purpose is to reduce the total energy consumption of electrolyze water by preparing cheap and accessible transition metal catalysts for hydrogen evolution,and replace oxygen evolution reaction?OER?with urea oxidation reaction?UOR?and methanol oxidation reaction?MOR?,which are to reduce the overpotential and accelerate the hydrogen evolution reaction.The main research contents of this paper are as follows:?1?A catalyst with better performance of HER is developed in 0.5 M H₂SO₄.CoSe₂/C nanocrystals are prepared by means of high temperature reaction on carbon carrier?XC-72R?,and the effect of temperature on CoSe₂/C nanocrystals is studied.The properties of CoSe₂/C nanocrystals annealed at different temperatures are compared in 0.5 M H₂SO₄.The results show that coral-like CoSe₂/C-650 nanocrystals have a high performance for HER with Tafel slope of 45.73 mV dec^-1 and onset potential of-196 mV vs.RHE.The stability maintained for 40 h and the Faraday Efficiency?FE?of H₂ is 98%.The outstanding HER performance of CoSe₂/C-650 is due to its characteristic cora-like frame CoSe₂nanocrystals.The construction of CoSe₂ based electrocatalyst reveals the relationship between temperature and hydrogen evolution activity,which provides a reference for the development of related catalysts.?2?The catalysts for urea oxidation reaction?UOR?as a replac to oxygen evolution reaction?OER?are developed in 1 M KOH.The bipolar of electrolyze water produces hydrogen?HER?and oxygen?OER?,respectively.Because UOR requires a lower overpotential than OER,it can degrade urea-rich wastewater pollution degrading.Ni_0.85Se/RGO catalyst was prepared by refluxing and pyrolysis.The electrooxidation performance of Urea is tested in 1 M KOH/0.5 M Urea solution.The results proved that Ni_0.85Se/RGO is a highly efficient and durable UOR catalyst with a onset potential of 1.36 V vs.RHE(corresponding to 10mA cm^-2).The low overpotential is beneficial to accelerate the reaction of hydrogen evolution.?3?Another anodic oxidation reaction replaces OER in alkaline conditions,namely methanol oxidation reaction?MOR?.The NiSe/RGO nanocrystic catalyst is prepared using a different preparation method.The methanol oxidation performance of NiSe/RGO is tested in 1 M KOH/0.5M MeOH solution.The results show that the MOR of NiSe/RGO-550 is the best,with a peak potential of 1.35 V vs.RHE lower than OER.It can effectively reduce energy consumption of electrolyze water with MOR instead of OER.MOR is also an anode reaction of direct methanol fuel cell.NiSe/RGO can effectively degrade methanol wastewater pollution and also provides a kind of effective catalystfor the development of fuel cell.