Study On Anode Nanocatalysts For Direct Borohydride-Hydrogen Peroxide Fuel Cell

The direct borohydride-hydrogen peroxide fuel cell（DBHFC） is a device that usees the sodium borohydride（NaBH₄） as a fuel to obtain electricity. It has attracted widely attention, for its.advantage, such as high energy density（9.3 Wh g-1） and high theoretical open circuit voltage（3.01 V）. The anode electrocatalyst is one of key effects in DBHFC. Nowadays, most of anode electrocatalyst for DBHFC are noble metals, such as Pt, Au, Pd and so on. However, high cost of noble metals hinders its large-scale application. While through alloying 3d transition metals with noble metals can improve the catalytic activity of catalyst, minimize the electrocatalyst cost and improve the fuel utilization efficiently.In this thesis, a series of higher catalytic activity and lower cost bimetallic nanocatalysts were synthesized by alloying 3d transition metals（Fe） with noble metals（Au or Pt）. The main contents as follows:1. Carbon supported Au-Fe bimetallic nanocatalysts（Au-Fe/C） are facilely prepared impregnation reduction method in aqueous solution with different atomic ratios. Cyclic voltammetry（CV）, chronoamperometry（CA）, and chronopotentiometry（CP） were used to study the electrooxidation behaviors of BH₄- and electrochemical active surface area（ECSA）, and then used as the anode electrocatalyst of direct borohydride-hydrogen peroxide fuel cell（DBHFC）. The results show that Au-Fe/C catalysts display higher catalytic activity for the direct electrooxidation of BH₄- than carbon supported pure Au nanocatalyst（Au/C）, especially Au50Fe50/C catalyst presents the highest catalytic activity among all asprepared catalysts. Besides, the single DBHFC with Au50Fe50/C anode obtains the maximum power density as high as34.9 mW cm-2, while the the maximum power density of Au/C anode catalyst is only21.8 mW cm-2 at the same condition.2. Carbon-supported Pt-Fe bimetallic electrocatalysts（Pt-Fe/C） with different atomic ratios are synthesized by impregnation reduction method. The morphology and structure of the prepared electrocatalyst were examined by transmission electron microscopy（TEM） and X-ray diffraction（XRD）. CV was used to study the electrooxidation of BH₄-and ECSA, and further analyzed the reasons of improved catalytic. The prepared electrocatalyst were used as anode catalyst for direct borohydride-hydrogen peroxide fuel cell（DBHFC）, The results show that Pt-Fe/Ccatalysts display higher electrocatalytic activity and cell performance than Pt/C, and among the as-prepared four catalysts, the DBHFC with Pt67Fe33/C anode obtained a peak power density as high as 65 mW cm-2, while only 21.8 mW cm-2 of Pt/C anode catalyst at the same condition.3. The electrooxidation behaviors and correlative kinetic characteristics on Au-Fe/C and Pt-Fe/C electrodes have been studied from the angle of kinetics. The apparent number of electrons involved in BH₄- electrooxidation on Au/C,Au-Fe/C,Pt/C and Pt-Fe/C electrodes have been calculated respectively. The apparent activation energy Ea for BH₄- oxidation on Au/C and Au50Fe50/C electrodes at-0.1 V and Pt/C and Pt67Fe33/C electrodes at-0.5 V have been calculated respectively.