Synthesis And Polyalcohol Electrooxidation Properties Of Transition Metal-based Composite Nanomaterials

The global shift in manufacturing towards carbon-free or carbon-negative technology demands urgent technological renovation.The exploration of clean energy sources is the foremost means of optimizing the fuel structure of the energy source with glycol and glycerol-based fuel cells being considered in recent years as a promising alternative energy source for the next generation of vehicles and portables.However,whether it is a direct glycol fuel cell or a direct glycerol fuel cell,problems such as low oxidation kinetics,incomplete C-C bond cleavage during the oxidation process and poisoning caused by the formation of carbon-containing intermediates on the catalyst surface,as well as incomplete oxidation reactions,have been reported for most electrocatalytic polyol oxidation nanocatalysts.This was extremely detrimental to the development of polyol fuel cell technology.Therefore,there is a requirement to select highly active and stable catalysts to reduce the hindrance present in the anode reaction in fuel cells.In this paper,a simple microwave synthesis method and a solvothermal method were used to modulate the morphology and properties of transition metal-based catalysts.The stability and activity of the transition metal-based catalysts were improved by the introduction of heteroatoms.The major studies are as follows:1.To achieve a breakthrough in the insufficient number of active sites while maintaining the excellent physicochemical properties of multilayered sheets of MXene,thereby achieving high performance with the minimum amount of reactants and thus reducing the cost of the catalyst.In this chapter’s work,water-soluble ultra-small MQDs were first prepared using a generic synthetic method,and then doped into Ni Fe nanosheets（NSs）by using a simple hydrothermal process.The successful preparation of the first MQDs-doped Ni Fe NSs catalyst is applied to the alkaline ethylene glycol oxidation reaction.The catalysts exhibited excellent electrocatalytic ethylene glycol oxidation activity by taking advantage of the high speed electron transfer properties and excellent reaction kinetics of MQDs,combined with the good adsorption of Ni Fe NSs to organic molecules.In addition,the catalyst morphology remained unchanged after12 h of I-t testing.The products of the electrocatalytic ethylene glycol oxidation reaction were explored using in situ FTIR and the presence of reaction intermediates as well as C-C bond breakage during the reaction was identified.We believe that this work could provide a new methodological guide for improving the catalytic activity of MOFs and could also provide new ideas for the design of other catalysts.2.A series of surfactant-free and ultra-small（4～5 nm）metastable crystalline phase-controlled MP_X/CNT（M=Pd,Pt,Ru,CNT is carbon nanotube）is synthesized in a household microwave oven by this ultra-fast phosphating synthesis method for the first time.Utilizing the microwave conductive properties of carboxylated multi-walled CNTs,the rapidly generated high-temperature environment temperature environment causes the reactants to rapidly sinter into the metastable phase Meanwhile,the shorter sintering time prevents the agglomeration to form the ultra-small size of the noble metal compounds.In situ FTIR of glycerol reveals that hexagonal Pd₇P₃/CNT has a good C-C bond breaking ability,which effectively converts glycerol to CO₂.They all reflected better electrocatalytic performance for basic polyalcohol electrooxidation than commercial Pt/C and even most of the reported catalysts.In addition,because the nanoparticles synthesized by microwave are firmly anchored on the CNTs,the catalyst has good stability during the oxidation process.What’s more,the hexagonal Pd₇P₃/CNT,monoclinic Pt₅P₂/CNT catalyst exhibited the best resistance to CO poisoning compared with that of commercial Pt/C,respectively.Such excellent polyalcohol electrooxidation catalytic activity stems from the introduction of P which promotes charge transfer,and the ultra-small nanometer-size increases the ECSA of the supported catalysts.This discovery will provide new general method guidance for ultra-fast phosphating synthesis of metastable crystalline phase-controllable ultra-small catalysts,which can be applied to other reactions.