The Controllable Synthesis And Performance Of Co(Ni) Based Electrocatalysts With Porous Nano -Assembly Structures

As the environmental deteration increasingly and the growing demand for sustainable en ergy of all over the world,environmentally friendly energy devices have drawed more and more attention.Among them,the air batteries,fuel cells and metal zinc air battery due to their safety and theoretically high energy density,are considered as very promising renewable energy technologies.Through the untiring efforts of the researchers for several decades,these energy technologies have carried on the experimental application in many fields.However,there are also many obstacles,such as,high cost,low resistance to methanol and poor long term stability.And the slow reaction kinectics of ORR?oxygen reduction reaction?OER?oxygen evolution reaction?and HER?hydrogen evolution reaction?are the major factors that have great influence on these energy devices.Generally,Pt or Pt-based alloy are regaded as electrochemical catalysts for ORR and HER,while Ru O₂ are used as electrochemical catalysts for HER.The high cost of these noble metal catalysts restrict the practical application of fuel cells to some extent.Thus,tremendous efforts need to be made for searching and exploring novel non-noble metal,low cost and earth-abundant catalysts.In this paper,mainly by simple hydrothermal way,we design and synthesize a series of hierarchical non-noble catslysts with special structure and morphology.We discuss the specific method,the main mechanism and great performance of these catalysts.The novel bifunctional and even trifunctional eclectrichemical catalysts have crucial meaning in providing some therotical and experimental references and new ideas for the research of energy systems.The main contents are summarized as following:To start with,we had successfully designed and synthesized a novel Flower–like Ni and N codoped hierarchical microspheres.This F-Ni/N-HPCMs elctrode was fabricated by a two-step method and the cost of the catalyst was effective.The catalysts owns more accessible active sites,like pyridinic N,graphitic N and M–Nx.They also have heriarchical strcture and unique morphology,which provide more micro,meso and marco pores for fast electran transfers and O₂ mass transporting.Moreover,F-Ni/N-HPCMs catalysts possess considerable specific surface area,making contribution to more active sites.Therefore,the F-Ni/N-HPCMs can exhibit superior ORR and OER performance and perform excellent in H₂–O₂ alkaline polymer electrolyte fuel cell?APEFC?.In addition,we had employed a simple facile hydrothermal method to synthesize a novel hierarchical hollow microspheres.The cobalt acetate,thioacetamide and glutathione were used as raw materials,at 140 ? for 12 h,Co₉S₈ was obtained.The process of the formation of Co₉S₈ is the Ostwald ripening procedure.The hollow Co₉S₈ was converted from solid spheres as the change of temperature.Wit h structure of rough surface and hollow microsphere,Co₉S₈ HMs-140 shows trifunctional performance,which is ORR,OER and HER in the same electrolyte.It has lower onset potential and higher stability compared to commercial Ru O₂ toward OER.Furthermore,Co₉S₈ HMs-140 also displays excellent in full water splitting,with a faradic yield of 96%.Finally,the Co?OH?Cl catalysts was prepared by a simple one-pot method,which is using cobalt acetate,ammonium chloride and hydrazine hydrate as raw materials followed by hydrothermal reaction without adding any surfactant.The obtained 3D hierarchical Co?OH?Cl microsphers was fabricated by numerous 2D nanoflakes,which result in the high specific area and more active sites.Co?OH?Cl reveal good bifuctional performance,demonstrated by OER,HER and water splitting experiments.And Co?OH?Cl perform better OERcatalytic activity compared to commercial Ru O₂ in terms of high limiting current density and long-term stability.In conclusion,by sophiscated idea and design,we synthesized a series of Co-based and Ni-based non-noble catalysts with unique structure and morphology,which cause excellent performance towards ORR,OER and HER.These bifunctional and even trifunctional catalysts reveal high potention in the application of sustainable energy.