Adjusting The Micro-nano Structure Of Electrode Surface And Its Application In Electrochemical Devices

Electrocatalysis technology can be used as the conversion-hub to realize the flexible conversion between chemical energy and electric energy.By preparing an efficient and high stable electrode,the reaction overpotential can be reduced.And the low cost is helpful for large-scale and economical energy conversion.The preparation and design of highly efficient reaction electrode depends on the reasonable regulation of the micro-nano structure of electrode,which is manifested in the regulation of the intrinsic activity of catalyst,electron transfer rate and mass transfer ability.The traditional preparation process of powder catalyst loading electrode needs binder.Although some electrodes have been successfully applied commercially,there is still a lot of room for improvement under high current density working conditions by improving the interface contact impedance,interface mass transfer capacity and stability of electrodes.How to design the micro-nano structure of the electrode interface and optimize the electrode reaction process are still the research difficulties in the field of energy electrocatalysis,which need to be solved urgently.Therefore,this paper is dedicated to the design and construction of electrode interface micro-nano array structure,flexible control of electrode interface infiltration,strengthen the mass transfer ability in the process of electrocatalytic reaction,preparation of integrated electrode with high activity and high stability,and obtained universal verification in different electrochemical systems.Specific research work is as follows:（1）Pt-based catalyst has a high hydrogen precipitation reaction（HER）intrinsic activity,but the application of Pt/C is limited by mass transfer.In practical application,the amount of precious metal is large,and the performance is poor under the condition of high current density.The regulation of the electrode interface makes it have super aerophobic characteristics,which can promote the product bubble release and improve the hydrogen evolution ability of low Pt composite electrode under high current density.In this paper,the integrated electrode of Pt-Co P was prepared by growing the Co P micro-nano array on the electrode surface and then loading the active sites of Pt clusters in situ.The Pt-Co P integrated electrode can cooperate with the excellent HER intrinsic activity of Pt itself,showing great performance improvement under the condition of high current density:only 125 m V potential is required under the condition of high current density of 500 m A cm^-2,and there is no attenuation phenomenon after stable operation for 24 h.The mass activity of Pt-Co P electrode is nearly 21 times higher than that of commercial Pt/C,and the utilization rate of unit Pt is improved.HR-TEM,XPS and XAFS showed that Pt was uniformly distributed on Co P micro-nano arrays in clusters with diameters of about 2.0 nm.The super-hydrophilic properties of Co P array are not only conducive to full contact of electrolyte,but also conducive to the transfer and removal of hydrogen bubbles,which greatly enhances the material transmission.The structure of Pt-Co P composite electrode realizes the efficient utilization of Pt,and its performance exceeds most reported values,which provides scientific guidance for the preparation of HER electrode with high activity,high stable and low cost.（2）Ethanol electrooxidation reaction（EOR）can replace the anode reaction of hydrogen production by electrolysis of water,reduce the reaction oxidation potential and increase the value of anode products.However,the EOR electrode still faces some problems such as high demand of precious metals,poor performance and poor stability under high current density conditions.Regulate the micro-nano array of electrodes,electrode interface with super hydrophilic properties,can strengthen the electrode under high current density of the liquid phase mass transfer ability,increase EOR performance ultimately.A micro-nano array structure was constructed on the surface of brass mesh by in-situ Ni ion etching replacement method.BM-Ni S electrodes with uniformly arranged Ni₃S₂ nanosheet arrays were prepared and screened by adjusting the etching degree.The BM-Ni S electrode can work stably for more than 100 hours at a current density of 100 m A cm^-2 corresponding to a reaction potential of 1.37 V.XRD,XPS,XAFS and in situ ATR-SEIRAS showed that Ni₃S₂ nanosheets formed on the electrode surface were the main active sites of EOR.At the same time,the active sites of Ni₃S₂ were compared respectively with three loading methods to explore the influencing factors of electrode activity and stability:the super-hydrophilic characteristics of the BM-Ni S electrode interface can meet the mass transfer requirements under high current density;The solid adhesion of the in-situ catalytic layer is also beneficial to improve the electrochemical activity and stability of the reaction.Finally,the BM-Ni S electrode showed high efficiency and stability in the test of EOR devices,and the results of nuclear magnetic analysis showed that the liquid phase products were all acetate,showing a good prospect of EOR process application.（3）Recharge-discharge Zinc-Air batteries（ZABs）have exclusive interfacial wettability requirements under different working conditions,which leads to limited mass transfer and greatly limits the utilization rate of catalysts.By adjusting the asymmetric infiltration characteristics of electrode interface,the different infiltration requirements of electrode interface during battery charging and discharging can be met,thus improving the efficiency and stability of ZAB.Firstly,Fe Co Ni-OH micro-nano array was constructed in situ on the surface of nickel foam,and the super-hydrophilic V-SA integrated electrode was prepared as the oxygen precipitation electrode.The D-SH electrode was prepared by co-modified manganese cobalt spinel catalyst with PTFE as an oxygen reduction electrode.V-SA and D-SH electrodes were rolled together to prepare Janus air electrode,which was applied to ZAB test.The Janus electrode can satisfy both the aerophilic interface required for ORR during discharge and the hydrophilic interface required for OER during charging.By comparing the performance of different structures of air electrodes,Janus electrode shows the highest battery performance,and the battery charging and discharging efficiency and stability are greatly improved.TheΔE corresponding to the 10m A cm^-2 current density is about 0.78 V,and the battery can stably carry out more than 1100 charge-discharge cycles,and the cycle time is as long as 720 h,which exceeds the performance of most reported ZABs.In summary,the integrated electrode with super-wettability was prepared by designing and building the micro-nano array structure of electrode interface to strengthen the mass transfer ability of electrocatalytic reaction process,which significantly improved the reactivity and stability of electrode,and was applied to different electrochemical systems.