Synthesis Of Three-dimensional Platinum-based Nanomaterials And Their Application In Direct Alcohol Fuel Cells

Seeking renewable resources to replace traditional fossil fuels is one of the major challenges worldwide.Direct alcohol fuel cells have received growing attention due to their high efficiency and environmental friendliness.Catalyst is the core of direct alcohol fuel cells,Pt-based nanomaterials are proven as the most effcient catalysts.However,because of the high cost of Pt and the unstable activities of Pt nanomaterials,the practical application of direct alcohol fuel cells has been hindered.This paper aims to reduce the cost of catalysts and improve the catalytic performance of the nanocatalysts.The nanomaterials are regulated mainly from the aspects below:morphology,structure and composition.Three-dimensional porous Pt_xCu_100-x nanochain networks with tunable compositions and three-dimensional hollow Pt（Au）Cu nanonetwork structures have been synthesized in this study.The electrocatalytic performances of these Pt-based three-dimensional nanomaterials for direct alcohol fuel cells were subsequently investigated.The main contents are as follows:1.By using ammonia as structure-director,hydrazine hydrate as reductant,bimetallic three-dimensional（3D）porous Pt_xCu_100-x nanochain networks(3D p-Pt_xCu_100-x NCNs)with tunable compositions were synthesized successfully through a facile one-pot strategy in aqueous solution.In this study,by regulating the proportion of Pt and Cu precursors,four kinds of 3D p-Pt_xCu_100-x NCNs with different composition were obtained as Pt₆₃Cu₃₇,Pt₄₆Cu₅₄,Pt₃₄Cu₆₆ and Pt₂₉Cu₇₁.All the as-prepared 3D p-Pt_xCu_100-x NCNs revealed enhanced electrocatalytic activity and durability for ethylene glycol oxidation and glycerol oxidation reaction compared with commercial Pt/C in alkaline solution.The mass activity all follows this order:Pt₄₆Cu₅₄>Pt₃₄Cu₆₆>Pt₂₉Cu₇₁>Pt₆₃Cu₃₇>Pt/C.The3D p-Pt₄₆Cu₅₄ NCNs achieve a mass activity of 8.38 A/mg_Pt for ethylene glycol oxidation reaction and 4.01 A/mg_Pt for glycerol oxidation reaction,which are 3.58-fold and4.01-fold that of commercial Pt/C,respectively.The ammonia mediated one-step synthetic strategy has the potential to prepare other promising 3D porous Pt-based nanomaterials in electrocatalytic applications.2.In this study,a simple strategy for the synthesis of 3D hollow Pt-based polymetallic alloy nanomaterials is designed.By using NaBH₄ as reductant in aqueous solution,Cu precursor was reduced to 3D Cu nanonetwork structures,and then using it as sacrificial template,the 3D hollow Pt（Au）Cu nanonetwork structures（3D h-Pt（Au）Cu NNWs）were synthesized by the replacement reaction of Pt precursors or Pt and Au precursors with Cu.Two kinds of hollow nanosrtuctures were obtained by this synthetic method,which were defined as 3D h-Pt₄₂Cu₅₈ NNWs and 3D h-Pt₃₈Au₁₇Cu₄₅ NNWs.The electrocatalytic properties of 3D h-Pt（Au）Cu NNWs were investigated by methanol,ethanol and ethylene glycol oxidation reaction under alkaline conditions,and compared with 3D non-hollow Pt（Au）Cu nanonetwork materials and commercial Pt/C.As a result,the hollow structure materials exhibited higher performance than the non-hollow materials with the same element composition,and all polymetallic alloy nanomaterials with 3D structures displayed higher catalytic performance than commercial Pt/C.3D h-Pt₃₈Au₁₇Cu₄₅ NNWs owned the best catalytic activity for methanol,ethanol and ethylene glycol oxidation reaction,the mass activity are 6.12 A/mg_Pt、8.53 A/mg_Pt and 12A/mg_Pt,which are 3.84-fold,7.35-fold and 4.23-fold that of commercial Pt/C,respectively.This study provides a simple synthesis strategy for the preparation of novel3D hollow Pt-based polymetallic nanostructures.It can be used for reference to synthesize high-efficiency Pt-based nanoelectrocatalysts.