The Preparation Of Polyaniline/platinum Composite Material And Its Application In Methanol Fuel Cell Catalyst

Energy and environment are two critical topics directly related to human sustainable development.Since the beginning of the 21st century,the problems of energy shortage and environmental degradation have become increasingly prominent and has been arousing the attention of mankind.The most important fossil energy sources such as coal,oil and natural gas are gradually depleted with the increasing consumption due to their non-renewability.Direct methanol fuel cell(DMFC)is an energy conversion device that can directly convert chemical energy coming out the electrochemical reaction of methanol fuel and oxidant into electrical energy.DMFC holds the advantages of pollution-free,simple structure and high energy conversion rate.It is one of the best solutions to address the challenges facing to the energy and environment.Today,the low electrocatalytic performance and poor stability of the anode catalyst for methanol has limited the industrialization and commercialization of DMFC.The preparation of efficient anode catalysts and the reduction of noble metal applications in one hand improve the fuel cell performance and in another hand reduce the cost of catalysts.In this paper,a series of catalysts were synthesized from the supporting materials,catalyst composition,surface structure and preparation methods.The electrocatalytic activity and anti-toxicity of methanol under alkaline conditions were studied.The specific work includes the following aspects:The fabrication of Pt/SPS@PANI and its electrocatalytic performance study.Polystyrene microfibers with the diameters of 1-2?m are first prepared by an electrospinning process.The polystyrene fibers were then sulfonalized and the negatively charged sulfonic acid groups were introduced.The as-obtained materials coupled with the positively charged aniline monomer were then in-situ polymerized to form sulfonated polystyrene@polyaniline composite fibers(SPS@PANI).The as-prepared composite fibers were then deposited with platinum nanoparticles and turned into Pt/SPS@PANI.after the optimization of the synthesis conditions.The electrocatalytic activity,electrochemical stability and anti-toxicity of Pt/SPS@PANI catalysts were finally investigated.The study indicated that Pt/SPS@PANI shows the good catalytic performance and its catalytic activity is about 1.5 times of those commercial Pt/C.(2)The impact of hollow PANI on the catalytic activity.In this study,the sulfonated polystyrene(SPS)of SPS@PANI was extracted to form the polyaniline hollow tubes(PANI)in order to not only improve the conductivity of the carrier but also increase the surface area of the supporting materials.The catalysts with the optimal electrocatalytic activity were obtained through optimizing the reaction temperature,reaction duration,raw material concentration.The electrocatalytic activity of the as-prepared Pt/PANI catalyst was about 2.4 times that of commercial Pt/C,and the anti-toxicity property was further improved.(3)The effect of the introduction of Ni and graphene.The introduction of non-precious nickel metal is expected to increase the electron interaction between precious metals and non-precious metals and thus improve the catalytic performance of the catalysts.The simultaneous introduction of graphene oxide is expected to enhance the connection of polyaniline microtubes and thus increase the surface area of the supporting matierlas and accelerate the electron transport rate.Due to the electronegativity difference between Pt and Ni is greater than the electronegativity difference between Pt and Ru,the influence of Ni to Fermi energy of Pt is more remarkable.The phenomenal change of the electron cloud density leads to the decrease of the Fermi energy of Pt,which effectively reduced the adsorption of CO on Pt.Graphene,a typical two-dimensional(2D)sp~2-hybridized carbon material,has attracted enormous attention due to its unprecedented electronic,thermal,and mechanical properties.The assembly of two-dimensional planar graphene with three-dimensional(3D)structures was designed to prevent the stacking of graphene and extend the surface of the catalyst support.The catalytic activity of the as-prepared PtNi/PANI@rGO catalyst has been improved with the introduction of new structures.Its performance was about 8.5 times that of commercial Pt/C,and the anti-toxic performance and stability of the catalysts were found to be largely improved.