Abstract
Carbon-supported PtRu nanoalloy (PtRu/C) is widely used as the anode catalyst for direct methanol fuel cells (DMFC), and an aqueous phase synthesis of PtRu/C is in high demand due to for energy-saving and environmentally-benign considerations, however, it is very challenging to attain stoichiometric reduction, good dispersion and a high alloying degree. Herein, we report a facile aqueous phase approach with dimethylamine borane (DMAB) as the reducing agent to synthesize a PtRu/C(DMAB). TEM, XRD, XPS and ICP-AES characterizations indicate that the structural parameters in the PtRu/C(DMAB) are improved significantly as compared to those obtained in a PtRu/C(NaBH4) and a commercial PtRu/C, contributing to an enhanced electrocatalytic performance. It turns out that the PtRu/C(DMAB) exhibits the highest methanol electro-oxidation (MOR) performance among all of the tested samples, with the peak current up to 1.8 times as much as that of the state-of-the-art commercial PtRu/C, corroborating the highest output power density in comparative DMFC tests. In-situ attenuated total reflection infrared (ATR-IR) spectroscopy correlates the higher methanol electro-oxidation performance of the PtRu/C(DMAB) with its enhanced CO resistance and CO2 generation. This simple aqueous synthetic approach may provide an alternative route for developing efficient anode electrocatalysts of DMFCs.
Highlights
Direct methanol fuel cells (DMFC) are promising energy-converter to drive portable devices owing to their high efficiency, low emissions and rich fuel supply [1]
dimethylamine borane (DMAB) is initially used in this work as the reductant to synthesis of a PtRu/C catalyst
The smaller apparent Tafel slope on the PtRu/C(DMAB) together with the larger oxidation peak current suggests that the DMAB-derived PtRu/C catalyst at least demonstrates a higher activity in a half cell measurement condition, deserving of a further test as the real anode catalyst FFigiguurere55
Summary
Direct methanol fuel cells (DMFC) are promising energy-converter to drive portable devices owing to their high efficiency, low emissions and rich fuel supply [1]. Dimethylamine borane (DMAB, (CH3)2NH·BH3), a water soluble small molecule with a milder but sufficiently strong reducing power [30], was initially developed in our group for the synthesis of a series of carbon supported catalysts such as Pd-B/C [31], Pt-B/C [32], Pt3Ni-B/C [32] and Pt3Co/C catalysts [33]. It is unknown whether the DMAB-derived PtRu/C(DMAB) yields better structure and performance towards MOR than the NaBH4-derived PtRu/C(NaBH4). In-situ attenuated total reflection infrared (ATR-IR) spectroscopy is applied to monitor the interfacial species on the catalyst surfaces during MOR to provide a molecular-level understanding of different performances
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