Study On RuO₂ Nanoparticles Modified Metal Hydroxide/Oxide And Its Enhanced OER Performance

Hydrogen as a clean energy is considered to be one of the most promising alternatives to alleviate energy crisis and environmental pollution.Electrolysis of water to produce hydrogen is considered to be the most sustainable way of producing hydrogen.Electrolysis of water includes two half reactions:hydrogen evolution reaction(HER)and oxygen evolution reaction(OER).Among them,anodic(OER)is the bottleneck of hydrogen production by electrolysis of water due to its slow four-electron reaction kinetics.At the same time,OER is also a semi-reaction of many other electrochemical reaction processes or electrochemical energy storage and conversion devices,such as carbon dioxide reduction,nitrogen reduction etc.At present,the best OER catalysts are still precious metal oxides based on ruthenium and iridium.In recent years,researchers have developed a large number of high performance OER electrocatalysts based on transition metals.However,most of these reported catalysts have better performance in alkaline solutions prepared in pure water.There are very few reports of electrocatalysts with excellent OER performance in the abundant seawater and neutral electrolytes on the earth.On the other hand,neutral electrolytes can avoid the disadvantages of using strong acid/alkali electrolytes,such as no need to use ion exchange membranes,and no corrosion of the electrolytic cell.At the same time,the neutral electrolyte can also be effectively matched with artificial photosynthesis and microbial fuel cells.At the same time,the neutral electrolyte can be effectively matched with artificial photosynthesis and microbial fuel cells.Therefore,it is of great significance to study electrocatalysts with high performance OER in seawater and neutral electrolyte.Therefore,in this paper,the OER performance of RuO₂nanoparticles in alkaline electrode solution,alkaline seawater and neutral electrolyte was improved by modifying the surface of transition metal hydroxide/oxide nanoarray with low load.(1)An array of RuO₂nanoparticles modified NiFe-based organic skeleton structure(MOF)nanosheets was designed and prepared,and then reconstructed into RuO₂nanoparticles modified NiFe-based hydroxide/hydroxyl oxide nanosheets driven by an electric field.The converted electrocatalyst exhibited excellent OER performance in both alkaline electrolyte and alkaline seawater.At 1 M KOH,the catalyst exhibits an ultra-low overpotential of 221 m V(400 m A cm^-2),a very small Tafel slope(31.9 m V dec^-1)and outstanding stability at high current densities(stable operation for 200 h at 840 and 1040 m A cm^-2).In alkaline seawater,the catalyst can drive a high current density of 1000 m A cm^-2with a minimum overpotential of 462m V.It also shows excellent stability and can run for up to 100 hours at a current density of 500 m A cm^-2.(2)Design and fabricate the Co₃O₄nanorod array modified with low loading RuO₂nanoparticles,and obtained improved neutral OER performance.In 1 M PBS neutral electrolyte,the RuO₂@Co₃O₄nanorod array exhibited excellent electrocatalytic activity(overpotential of 365 m V at 10 m A cm^-2),OER reaction kinetics(Tafel slope 53 m V dec^-1)and stability(100 hours of stable operation at 10m A cm^-2).At the same time,RuO₂@Co₃O₄nanorod array also has enhanced OER performance in alkaline electrolyte.DFT theoretical calculation and structural characterization show that RuO₂nanoparticles can effectively control the electronic structure of Co₃O₄and Co OOH produced in situ during the OER process,and accelerate the kinetics of the four reaction steps of the oxygen evolution reaction.