Study On Properties Of Pd Based Catalyst Composite Support For Anode Of Direct Formic Acid Fuel Cell

In recent years,Direct Formic Acid Fuel Cell（DFAFC）has been paid close attention by researchers.Because it has many advantages,such as high theoretical open circuit voltage,high safety in the use process,low environmental pollution and so on,DFAFC has a very wide application potential and development prospect.In DFAFC,the selection of anode catalysts is very important.At present,the most widely used catalysts are Pt and Pd based catalysts.For the oxidation of formic acid,Pd based catalysts have better performance than Pt based catalysts.In order to further improve the stability and activity of Pd based catalysts,a variety of composite supports were synthesized and Pd based catalysts were prepared through composite supports,Electrochemical test and physical characterization test are used to study the performance of the catalyst.The main research contents are as follows:Pd/g-C₃N₄-C catalyst was prepared by mixing different contents of g-C₃N₄ with Vulcan XC-72.The electrochemical test showed that the addition of g-C₃N₄significantly improved the performance of Pd/C catalyst.When the content of g-C₃N₄accounted for 30%of the total mass of the support,the performance of the catalyst reached the best.At this time,the electrochemical active area of Pd/g-C₃N₄-C（30%）catalyst was 44.41m~2g^-1,It is 1.44 times that of Pd/C catalyst.In the cyclic voltammetry curve in formic acid solution,the current density of positive scanning oxidation peak reaches 49.63m A cm^-2,which is 2.94 times that of Pd/C catalyst.After stripping g-C₃N₄ by"secondary calcination",the specific surface area is greatly improved.The electrochemical active area of the synthesized Pd/g-C₃N₄-C NS catalyst is 65.49m~2g^-1,which is 1.47 times that of Pd/g-C₃N₄-C（30%）catalyst and 2.13times that of Pd/C catalyst,In the cyclic voltammetry curve of formic acid solution,the current density of positive scanning oxidation peak reaches 57.18m A cm^-2,which is1.15 times that of Pd/g-C₃N₄-C.Fe₂O₃/C composite support was prepared by mixing Fe₂O₃ with Vulcan XC-72,and then Pd-Fe₂O₃/C catalyst was synthesized.The electrochemical test showed that the addition of Fe₂O₃ could improve the electrochemical performance of the catalyst.The electrochemical active area of Pd-Fe₂O₃/C catalyst was 33.86m~2g^-1,which was 1.1times that of Pd/C catalyst,In the cyclic voltammetry curve of formic acid solution,the positive sweep peak current density is 25.22m A cm^-2,which is 1.49 times that of Pd/C catalyst.Fe₂O₃/g-C₃N₄-C NS composite carriers were prepared by mixing different contents of Fe₂O₃ with Vulcan XC-72 and g-C₃N₄,and Fe₂O₃/g-C₃N₄-C NS（5:3:7）,Fe₂O₃/g-C₃N₄-C NS（2:3:7）and Fe₂O₃/g-C₃N₄-C NS catalysts were synthesized with Pd particles supported on them.The electrochemical test showed that the performance of the catalysts reached the best when Fe₂O₃:g-C₃N₄:C=2:3:7,The electrochemical active area obtained in the cyclic voltammetry test is 71.87m~2g^-1,which is 1.1 times that of Pd/g-C₃N₄-C NS catalyst.In the cyclic voltammetry curve of formic acid solution,the forward sweep peak current density is 61.96m A cm^-2,which is 1.08 times that of Pd/g-C₃N₄-C NS catalyst.Pd-SnO₂/C catalyst was synthesized by SnO₂/C composite support prepared by SnO₂ and Vulcan XC-72.Its performance was studied by electrochemical test.The results showed that the addition of SnO₂ improved the electrochemical performance of the catalyst.In the cyclic voltammetry curve of 0.5 mol L^-1 H₂SO₄,the electrochemical active area of Pd-SnO₂/C catalyst was 46.99m~2g^-1,which was 1.53 times that of Pd/C catalyst,In the cyclic voltammetry curve of formic acid solution,the forward scanning peak current density is 27.87m A cm^-2,which is 1.65 times that of Pd/C catalyst.On the basis of Pd/g-C₃N₄-C NS catalyst,different proportions of SnO₂ were added to the support material to synthesize Pd-SnO₂/g-C₃N₄-C NS catalyst.Cyclic voltammetry in 0.5 mol L^-1 H₂SO₄ showed that the electrochemical active area of Pd-SnO₂/g-C₃N₄-C NS（2:3:7）catalyst was 89.97m~2g^-1,which was 1.37 times that of Pd/g-C₃N₄-C NS catalyst,In the cyclic voltammetry curve of formic acid solution,the forward scanning peak current density is 67.71 m A cm^-2,which is 1.18 times that of Pd/C catalyst.