Design,Construction And Oxygen Evolution Reaction Performance Of Fe/Co/Ni-Based Nanoporous Catalysts

Hydrogen production from electrochemical water splitting is a potential and valuable technology for solving the future energy crisis.However,this technology is limited by the anode reaction,which affects the efficiency of the entire reaction system.As the emphasis of the catalytic reaction,the high-performance Oxygen Evolution Reaction(OER)catalyst can reducing the overpotential,thereby reducing the potential required for the entire water splitting system as well as efficient energy conversion.Therefore,the main challenge is finding high-performance and low-cost OER catalysts.Nanoporous materials have great potential because of their multiple active site exposure,open pores for electrolyte transport,pore-limited enhancement of intermediate species reactions,and internal curvature synergistic active site reactions.However,the current porous catalyst still has some problems in terms of pore utilization rate,actual active site recognition and theoretical potential breakthrough.Herein we mainly focused on the the design and preparation of high performance OER catalysts.A series of nanoporous materials were obtained by means of regulating synthetic methods,improving morphology,composition,and basic structure.These nanoporous materials can exhibit their inherent advantages and the special properties after optimization and optimization as compared to conventional nanoporous materials,thus resulting to excellent OER performance.More importantly,the actual active sites of the porous materials for the OER and the devices coupled with other reactions are also discussed and studied in detail in order to helps in a progressive understanding of the reaction mechanism and practical applications.The specific research content is as follows:1.A nanoporous Ni Fe-based material(NP-Ni Fe)is prepared by simply dealloying of Ni Fe Al ternary alloy ribbons.The the tremendous active sites exposed by the porous structure make the NP-Ni Fe have excellent OER performance.In order to break through the limitation of electrochemical hydrogen production by OER theoretical potential(1.23 V vs.RHE),urea oxidation reaction requires a lower theoretical potential(0.37 V vs.RHE)was introduced into the system.2.A phase-separated Co Al alloy ribbon precursor was designed and prepared by adjusting the atomic ratio of Co and Al.The Co-based hierarchical porous material(HP-Co)was directly obtained by one-step dealloying in the modified alkaline solution.The HP-Co shows better OER performance than Co-based nanoporous materials(NP-Co),and the superior performance are derived from the effective contact with the electrolyte brought by macropores.More notably,this phase separation dealloyed strategy can be further extended to prepare heteroatoms doped hierarchical porous metal.3.A bifunctional carbon-encapsulated nickel-nickel oxide(Ni?Ni O@C)porous nanorods with scalable and robust electrocatalyst for overall water-splitting has been fabricated via carbonization and further oxidation of a Ni-based MOFs.Because of the effect of a heterojunction formed between Ni O and Ni at the Ni/Ni O interface,Ni?Ni O@C is an efficient electrocatalyst for electrocatalytic reaction.Ni?Ni O@C nanorods show enhanced water splitting activity compared to Ni@C nanorods.Furthermore,it was confirmed by intuitive comparison that the increase in intrinsic activity comes from the formation of the interface.Moreover,overall water-splitting is achieved at a cell voltage of 1.70 V at a current density of 10 m A cm^-2.4.The CoFe phosphide(Co_0.4Fe_0.28P)and CoFe sulfide(Co_0.37Fe_0.26S)porous nanocubes(NCs)were synthesized by heating CoFe-based Prussian blue analogues precursors under different atmosphere.The prepared Co_0.4Fe_0.28P and Co_0.37Fe_0.26S NCs have defined stoichiometry and larger surface area,which revealed excellent electrocatalytic activities toward OER in alkaline condition.Co_0.4Fe_0.28P and Co_0.37Fe_0.26S nanocubes show an excellent electrocatalytic performance for the OER in 1 M KOH,achieved a current density of 10 m A cm^-2 at 1.50 V vs.RHE which are superior to the commercialized Ir O_xcatalyst.Furthermore,we also briefly study the electrochemical oxidation driving influence of Co_0.4Fe_0.28P and Co_0.37Fe_0.26S NCs for exposed active sites and further discovering that sulfides show a better driving effect.5.A method for dissociating self-assembly of MOFs was deliberately designed to prepare nanoporous hydroxide microspheres.The OH^-derived from the dissociate of acetic acid-based MOFs was employed as a component and promoter to prepare hydroxides.We noted that the as-prepared nanoporous macrospheres with poor crystallinity,derived from the insufficient of OH^-during the dissociate proess.Therefore,the crystallite composition has a large number of favorable boundary sites for electrocatalysis.Meanwhile,not only this synthetic strategy can effectively regulate the proportion of components,but also it is an reliable way to prepare other elemental materials.Due to the advantages of boundary sites for electrocatalysis,multi-boundary Co_2.6Fe hydroxide nanoporous microspheres have excellent HER and ORR properties while outstanding OER performance,expanding their application potential.They have great potential in the overall water-splitting and the rechargeable Zn-Air battery.