Synthesis of Carbon-supported Pt-Ni nanoparticles as anode catalyst for high performance of direct borohydride-hydrogen peroxide fuel cell

Fuel cells have been extensively studied over the last fivedecades and increasing resources have been used to bring themto a commercial stage and to develop alternative fuels to hydrogen.Aspromising power sources for space and underwater applications, direct borohydride–hydrogen peroxide fuel cells (DBHPFCs),comprised of BH oxidation at the anode and H O reduction at the cathode, have attracted increasing attentions recently [1–6].In this study, Pt/C (20wt.%)cathode andPt-Ni(1:1)/C anode (20 wt.%)were prepared by the borohydride reduction method.Briefly: Carbon black powder (Vulcan XC-72, Cabot Inc.) was used as a support for the catalyst,H2PtCl6·6H2O (Merck, 99.99%) and NiCl2 (Merck, 99.99%)were used as precursors. Thecarbon black was ultrasonically dispersed in a solution of ultrapure water and isopropyl alcohol for 2 h. The precursors were added to the ink and then mixed thoroughly for another 2 h. The pH value of the ink was adjusted by a NaOH solution to 9 and then raised the temperature to 80 ◦C. Asolution of 0.1 mol L−1NaBH4 was added dropwise into the mixtures, and the bath was stirred for 3 h. The catalyst powderswere dried in a vacuum oven for 3 h at 80 ◦C and stored in a vacuum vessel.To obtain a uniform high purity film, Nafion® 117 were cleaned with a standard treatmentprocedure was addresed in ref [7].Prepared Ni-Pt/C and Ni/C powder were mixed with 5% nafionsoloution, water and isopropyl alcoholseparately to form catalyst ink.This ink brushed oncarbon cloth with Gas diffusion layer(GDL). The loading of GDL on carbon cloth was 2 mg.cm-2and the loading of cathode (Ni/C) catalyst ink was 0.5 mg.cm-2 but the loading of anode catalyst ink (Pt-Ni/C) was 1 mg.cm-2. Finally anode, cathode and pre-treated Nafion ® 117 membranewere sandwiched together and hot pressed.The effective geometrical area of the anode and cathode was 5 cm2.In this study, the influences of different operational conditions such as cell temperature, sodiumborohydride concentration, oxidantconcentration on the performance of direct borohydride fuel cellwere investigated. The experimental results showed that by increasing the temperature from 25oC to 60oC ,power density was increased from 59.36 to 98.52 mW.cm-2 when we use NaBH4 2M + H2O2 2M and by increasing thesodiumborohydride concentrationfrom 1M to 2M at 60oC power density was deacreased from 106.628 to 98.52 mW.cm-2and by increasing the hydrogenperoxide concentration from 1M to 2M at 60 oC power density was increased from 97.208 to 98.52 mW.cm-2. The maximum powerdensity which was achieved by Liu. X. et. al with Pt/graphene was 42 mW.cm-2[8].

Keywords:

Borohydride oxidation , hydrogen peroxide , Pt-Ni/C , Fuel cell performance