A highly efficient alkaline HER Co-Mo bimetallic carbide catalyst with an optimized Mo d-orbital electronic state
A highly efficient alkaline HER Co-Mo bimetallic carbide catalyst with an optimized Mo d-orbital electronic state
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一种高效碱性 HER Co-Mo 双金属碳化物催化剂，具有优化的 Mo d 轨道电子态
DOI：
10.1039/c9ta02886b
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发表时间：
2019-05-28
影响因子：
11.9
通讯作者：
Peng, Huisheng
中科院分区：
文献类型：
--
作者：
Liu, Gejun;Bai, Haipeng;Peng, Huisheng
用于碱性析氢反应的高效催化剂被不断追求，以加速水裂解的动力学并提高可再生能源向化学原料的转化。在众多的候选者中，无贵金属的Mo 2C催化剂是受欢迎的，因为它们的成本低，丰度和类似的d-轨道电子状态的现有技术的铂。然而，由于高价Mo物种在Mo 2C中的高空d轨道密度，HER性能受损。我们的理由是，引入调制器到Mo 2C框架，可以降低空d-轨道密度和价态的Mo可能是一种有效的方式来优化HER能量学。在此，受3d金属的多功能电子结构的启发，我们进行了第一性原理计算，使用3d金属Co作为Mo 2C的掺杂剂来构建Co-Mo三元碳化物，并发现Co掺入后增强的HER活性。我们进一步合成了Co-Mo碳化钨催化剂。所得催化剂具有优异的碱性HER性能，在-10 mA cm（-2）下的最低过电位为-46 mV，低Tafel斜率为46 mV dec（-1），并且在500 h反应后具有良好的稳定性而没有任何衰减。X射线吸收光谱研究表明，Mo的价态被Co掺杂剂降低，我们提出，Mo的价态的降低应该是更好的HER性能的碳化硅比散装Mo 2C的原因。
Efficient catalysts for the alkaline hydrogen evolution reaction are continuously pursued to accelerate the kinetics of water splitting and enhance the conversion of renewable energy to chemical feedstock. Among numerous candidates, noble-metal-free Mo2C catalysts are favored because of their low cost, abundance and similar d-orbital electronic state to the state of the art platinum. However, due to the high empty d-orbital density of high-valence Mo species in Mo2C, the HER performance was impaired. We reason that introducing modulators into the Mo2C framework that could decrease the empty d-orbital density and valence states of Mo may be an efficient way to optimize the HER energetics. Herein, inspired by the versatile electronic structures of 3d metals, we carried out first principles calculations using 3d metal Co as a dopant of Mo2C to construct Co-Mo bimetallic carbide and found an enhanced HER activity after Co incorporation. We further synthesized a Co-Mo bimetallic carbide catalyst. The obtained catalysts achieved excellent alkaline HER performance with the lowest overpotential of -46 mV at -10 mA cm(-2), a low Tafel slope of 46 mV dec(-1) and great stability without any decay after a 500 hour reaction. The X-ray adsorption spectroscopy study showed that the valence state of Mo was decreased by the Co dopant and we propose that the decrease of Mo valence states should be the reason for the better HER performance of the bimetallic carbide than bulk Mo2C.