Study On Overall Water Splitting Of Functionalized Graphite Paper Supported And Regulated Nickel-cobalt Based Catalyst

The development of cheap and efficient catalysts for hydrogen production from electrolyzed water is the key to achieving sustainable energy use.So far,modification strategies based on spatial morphology,chemical composition,interface effects,etc.have been used to improve the hydrogen production performance of hydrogen electrolysis catalysts.However,the choice of electrode materials to support these catalysts will also affect their catalytic activity,which will affect the performance of hydrogen production.Therefore,it is necessary to study the physical and chemical properties of the supporting electrode.In this paper,the functionalized graphite paper?FGP? supporting electrode was prepared by electrochemical exfoliating method,and the content of oxygen functional groups on the surface of FGP was adjusted by changing the exfoliating time.The FGP support electrode with the best oxygen functional group content was determined by physical and electrochemical analysis,and then the Ni-Co-based catalyst supported by the FGP electrode was grown in situ by microwave hydrothermal synthesis.Finally,the Ni-Co-based catalysts supported by FGP electrodes with different oxygen functional group contents were studied for overall water splitting performance and the catalytic mechanism was discussed.Furthermore,a low-cost,high-efficiency and stable non-noble metal-based bifunctional electrocatalyst that can be used for hydrogen production by overall water splitting under alkaline conditions was developed.The main conclusions are as follows:?1?FGP electrode and its supported Ni-Co-based catalyst.Comprehensive analysis of the Field Emission Scanning Electron Microscope?FE-SEM?,Electrochemical Double Layer Capacitance(C_dl),Electrochemical Impedance Spectroscopy?EIS? and Resistivity of the FGP electrode at different exfoliating times found that when the exfoliating time was 40 s,the percentage of oxygen functional groups on the surface of the FGP electrode is 0.44.The FGP electrode(record as FGP_0.44) surface exhibited the most surface active sites,the lowest electrical impedance value and the highest electrical conductivity,indicating that it can provide the most favorable conditions for the growth of the catalyst as a supporting electrode.Analysis of the overall water splitting performance of Ni-Co-based catalysts grown on graphite paper electrodes with different oxygen functional groups in situ showed that the NiCo₂S₄-NiCo₂O₄?NCS-NCO?/FGP_0.44 electrode has the lowest overall water splitting performance,confirmed the FGP_0.44support electrode is the best support electrode for anchoring Ni-Co-based catalysts.This innovative self-supporting electrode exhibits extremely high electrocatalytic activity.It requires a battery voltage of 1.481 V in 1 M KOH electrolyte to achieve a current density of 10 m A cm^-2,which is much lower than that of precious metals RuO₂/FGP_0.44?Pt/C/FGP_0.44electrode?1.583 V?.This work provides us with an electrode material that can effectively support the in-situ growth of the transition metal-based bifunctional electrocatalyst.?2?Catalytic mechanism of Ni-Co-based electrocatalyst.We have prepared Ni-Co-based catalysts supported by FGP electrodes with different oxygen functional group contents:NCS-NCO/FGP_0.48,NCS-NCO/FGP_0.35,NCS-NCO/FGP_0.44,NCS-NCO/FGP_0.41and different Ni-Co catalysts supported by FGP_0.44 electrode:Nickel-based Sulfide-Nickel-based Oxide?NS-NO?/FGP_0.44,Cobalt-based Sulfide-Cobalt-based Oxide?CS-CO?,NCO/FGP_0.44,respectively.And analyze their physical and electrochemical performance under Oxygen evolution reaction?OER? and hydrogen evolution reaction?HER?conditions.The results show that the NCS-NCO/FGP_0.44 electrode has a unique cellular porous nanosheet network,intimate contact with the NCS-NCO heterointerface and a bimetallic active center with adjustable electrons.At 10mA cm^-2 current density,the required OER and HER overpotentials were as low as 117 mV and 145 mV,respectively.This optimal spatial morphology and chemical composition leads to rapid mass transfer and electron transfer processes during electrocatalysis,which improves OER/HER kinetics.This work provides a new method for constructing an industrialized overall-water splitting bifunction electrocatalyst with high efficiency,low cost and good stability.