Structure Regulation And Electrochemical Performance Of Iron Triad(Fe,Co,Ni) Nanomaterials

Many advanced technologies for clean energy conversion,for example fuel cells,metal-air battery,and water electrolysis,are the subject of both extensive fundamental and utilitarian studies.The electrochemical progresses of oxygen electrode are the core of these energy conversion technologies.The most arguable critical problem is how to effectively catalyze these reactions by electrocatalysts.In the past few years,transition metal materials,especially iron traid(Fe,Co,Ni)nanomaterials,which show high catalytic activity in oxygen electrochemical progress,have been explored as alternatives of precious metal catalyst.The structure regulation and electrochemical performance of iron traid(Fe,Co,Ni)nanomaterials have been studied in this paper.The following is the content in detail and the achieved results:The targeted NiFe-LDHs were prepared according to the separate nucleation and aging steps(SNAS)method.We tuned the crystallinity and sheet size of NiFe-LDHs by varying the aging temperature and altered the intercalation anions to discuss the relationship between the LDH nanostructure and oxygen evolution reaction performance.It was noticed that the lower the aging temperature applied,the lower the crystallinity of LDH and the intercalation anions was tuned by varying the ratio of the raw material in the synthesis progress.Based on the electrochemical performance and morphology results,two aspects may give great impact on the OER performance under given NiFe-LDH:one is the size and crystallinity of catalysts,the other is the intercalated anions between LDH's layers.The lower the crystallinity LDHs with the lower the crystallinity have the more active sites,as verified by OER data.Interlayer spacing was tuned by the different intercalated ion,which affect the charger transferring resistance and the exchange ability.Our comprehensive understanding of the LDH-catalyzed OER process could be extended for synthesizing better layered materials for OER.Bescides,we report a room-temperature synthetic NiFe-LDH as an excellent oxygen evolution catalyst.The Co1-xS/G hybrids with uniformly deposited Co1-xS nanoparticles on graphene could be obtained by simply annealing the mixed precursor in a horizontal tube furnace within several hours.Different from the time-consuming,post-processing complex synthesis method previously reported,this way of synthesis process is simple,short time-consuming,without post-processing and reduce the pollution to the environment.It is observed that the solvent species and the component should be optimized to achieve a desirable morphology.Electrochemical results demonstrated that the Co1-xS/G possesses excellent catalytic activities for both ORR and OER.The Co1-xS/G exhibited comparable ORR performance with Pt/C catalyst benchmark and superior to Ir/C toward OER.The large number and small size of Co1-xS nanoparticles provide many active sites for oxygen electrochemical progress and the strong interaction between Co1-xS and graphene can serve as efficient bridges for electron transferring which result in the Co1-xS/G possesses excellent catalytic activities for both ORR and OER.We also developed a scalable one-step strategy for synthesizing graphene-based metal sulfide nanocomposite...