The Design Of Highly Efficient Electrocatalysts For Borohydride Electrooxidation Based On Noble Metal

Fuel cell is an efficient electrical energy conversion device,which can directly convert the chemical energy into electrical energy without fuel burning.It is the first green energy device in the future.Direct borohydride fuel cell?DBFC?using NaBH4as fuel has the advantages of high voltage?3.01 V?and high specific energy(9.3 Wh g^-1).Compared with other fuels?such as hydrogen,methanol and ethanol?,NaBH₄ is easier to transport and store,because NaBH4 is solid at room temperature.However,most of the materials used in catalytic NaBH4 electrooxidation reaction are precious metals?Pt,Au,etc.?,and precious metals are relatively expensive,which will lead to the increase in the production cost of DBFC,thus limiting its large-scale application.Therefore,it is necessary to develop catalyst materials with low cost and high catalytic performance.For the problems existing in DBFC,in this paper,Au-Sn/C,Au-Sn/C and new biomass activated carbon carrier?A-LZT?supported Pd catalyst?Pd/A-LZT?were synthesized and their catalytic properties for BH₄^-electrooxidation were studied.?1?Au/C and Au-Sn/C catalysts were synthesized by Impregnation-reduction method,and the morphology and crystal shape of Au/C and Au-Sn/C catalyst materials were detected by XRD and TEM.XRD test showed that the average particle sizes of Au/C,Au₈₅Sn₁₅/C,Au₇₀Sn₃₀/C and Au₅₀Sn₅₀/C nanoparticles were 4.4 nm,4.2nm,3.8 nm and 4.1 nm,respectively.After a series of electrochemical tests,the properties of Au/C and Au-Sn/C catalysts to the electrooxidation of BH₄^-were studied.The experimental results showed that adding Sn to Au/C could enhance the ability of Au to BH₄^-electrooxidation,and Au₇₀Sn₃₀/C had the best electrocatalytic performance.?2?Pd/C and Pd-Sn/C were synthesized by dipping reduction method in the aqueous phase system by continuously adjusting the molar amount of Pd and Sn.Then,the catalytic performance of Pd/C and Pd-Sn/C to BH₄^-electrooxidation was compared through a series of electrochemical tests.The test results show that Sn as co-catalyst can not only reduce the amount of Pd,but also the catalytic performance of Pd-Sn/C to BH₄^-electrooxidation reaction is significantly higher than that of Pd.Finally,RDE test was used to obtain the number of electrons transferred by BH₄^-on Pd/C,Pd₇₅Sn₂₅/C,Pd₅₀Sn₅₀/C and Pd₂₅Sn₇₅/C electrodes,respectively 3.7,3.8,3.9 and?3?By using clean lotus seeds as carbon source,calcined in high temperature tube furnace to prepare the carbon material.Then biomass carbon and KOH were fully mixed and calcined again at high temperature to obtain A-LZT.Finally,Pd/C and Pd/A-LZT catalyst materials were obtained by dipping reduction method.The shape,size and crystal shape of the catalyst were detected by XRD and TEM.XRD test data showed that the particle sizes of Pd/C and Pd/A-LZT nanomaterials were 4.1nm and 4.0 nm respectively.Through electrochemical characterization,the electrocatalytic activities of Pd/C and Pd/A-LZT on BH₄^-electrooxidation were respectively investigated.The experimental results showed that the electrocatalytic performance of Pd/A-LZT was higher than that of Pd/C catalyst.