Design and Fabrication Three-Dimensional Structure Electrode and Its Application in NaBH4 Electrooxidation and H2O2 Electroreduction
We reported a newly designed and fabricated electrode with three-dimensional structure. The electrode consists of a conducting nanoarray substrate and Pd nanoparticles. The substrate is an array of TiO2 nanowires with a carbon coating layer prepared via a thermal evaporation method. Pd nanoparticles were electro-deposited on the substrate surfaces by the potentiostatic pulse method. The electrode exhibited excellent catalytic performance for NaBH4 electro-oxidation. The current density for NaBH4 electro-oxidation at the electrode (524 mA mg-1) is about 5 times of that at conventional Pd/C (100 mA mg-1). This enhanced performance is likely to be due to the improved mass transport of NaBH4, good electronic conductivity and high Pd utilization of the electrode.
We alos reported a porous (Co, Mn)3O4 nanowires freely standing on Ni foam electrode, which are synthesized via a template-free growth method, followed by a thermal treatment in the air. Results show that thermal treatment leads to the conversion of solid nanowires of MnCO3+CoCO3 to porous nanowires of (Co, Mn)3O4 via decomposition and reconfiguration, which is identified to be the catalytic active component for H2O2 electroreduction. The nanowires calcined at 300 °C exhibit the highest activity for the H2O2 reduction and a current density of 329 mA cm-2 is obtained in 3.0 mol dm-3 KOH + 0.6 mol dm-3 H2O2 at -0.4 V (vs. Ag/AgCl, KCl). The catalytic activity of (Co, Mn)3O4 nanowires is almost twice than that of Co3O4nanowires. The enhanced catalytic activity is explained by the decrease in the energy barrier of O-O bond cleavage caused by the introduction of Mn.
In conclusion, compared to conventional fuel cell electrodes fabricated by mixing active materials with conducting agents and polymer binders, this three-dimensional structure electrode directly grown on substrate has superior mass transport property, which combining with its low-cost and facile preparation, make it a promising electrode for DBHPFC.
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