Carbon-supported platinum and palladium nanoparticles were studied toward the oxidation of several boranes (namely ammonia–borane (AB), dimethylamine–borane (DMAB), hydrazine–borane (HB), and hydrazine–bis-borane (HBB)); only palladium is capable to oxidize directly and efficiently these fuels, as platinum first decomposes the boranes and then valorizes the evolved H₂ and adsorbed H_ad. Changing the nature of the borane fuel enables modulation of the borane oxidation performances at palladium electrodes; the best compromise is reached with HB (HBB suffers safety issues, and AB and DMAB are poisoned by the “counter-fragment” and/or its electroinactivity for any electrooxidation reaction). As a result, with a Pd/C electrode, HB oxidation is possible at low potential (close to the theoretical value), which holds promise for direct alkaline fuel cell applications. The temperature, HB concentration, and palladium nanoparticle loading on the electrode have remarkable effects, which shows that the “direct” electrooxidation of the borane fuel (BH₃OR) or of its adsorbates may compete with its spontaneous catalytic decomposition/hydrolysis into H₂ followed by electrooxidation of H₂ (HOR). The study also highlights that the reactant time of residence influences the pathway and completion of the reactions. These results demonstrate that, using suitable electrocatalysts, well-structured electrodes, and adequate borane fuel, the BH₃OR thermodynamic onset potential value and the theoretical number of electrons per fuel moiety (n_e^– = 10 in the case of HB, 6 for the borane fragment and 4 for the hydrazine one) can nearly be reached, at reasonably low anode potential, which paves the way toward optimization of direct HB fuel cell systems.

中文翻译：

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Pd / C和Pt / C电催化剂上普遍存在的硼烷燃料电氧化：有望成为直接的肼-硼烷燃料电池

研究了碳负载的铂和钯纳米粒子对几种硼烷（即氨-硼烷（AB），二甲胺-硼烷（DMAB），肼-硼烷（HB）和肼-双硼烷（HBB））的氧化作用。只有钯才能够直接有效地氧化这些燃料，因为铂首先分解硼烷，然后使析出的H ₂和吸附的H _ad变价。。改变硼烷燃料的性质可以调节钯电极上的硼烷氧化性能；HB是最好的折衷方案（HBB遇到安全问题，AB和DMAB会因“反片段”和/或其对任何电氧化反应的电惰性而中毒）。结果，使用Pd / C电极，在低电势（接近理论值）下可能发生HB氧化，这为直接碱性燃料电池应用提供了希望。电极上的温度，HB浓度和钯纳米颗粒负载具有显着影响，这表明硼烷燃料（BH ₃ OR）或其吸附物的“直接”电氧化可能与其自发的催化分解/水解为H ₂竞争然后进行H ₂（HOR）的电氧化。该研究还强调指出，反应物的停留时间会影响反应的路径和完成。这些结果证明，使用合适的电催化剂，结构良好的电极，和适当的硼烷燃料中，BH ₃或热力学开始电位值和每个燃料部分的电子的理论数（ñ _{ë ^-}在HB，6条，的情况下= 10在较低的阳极电位下，硼烷片段和肼的4几乎可以达到，这为直接HB燃料电池系统的优化铺平了道路。