MXene nanoribbons as electrocatalysts for the hydrogen evolution reaction with fast kinetics.
MXene nanoribbons as electrocatalysts for the hydrogen evolution reaction with fast kinetics.
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DOI：
10.1039/c8cp02635a
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发表时间：
2018-07
期刊：
影响因子：
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通讯作者：
Xiaowei Yang;Nan Gao;Si Zhou;Jijun Zhao
中科院分区：
文献类型：
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作者：
Xiaowei Yang;Nan Gao;Si Zhou;Jijun Zhao
MXene是一类新型的二维材料，由于其化学性质的多样性、上级导电性和稳定性而引起人们极大的兴趣。近年来，人们在实验中合成了纳米带、纳米点等MXene的纳米结构，这些纳米结构表现出了独特的性质，拓展了MXene的应用范围。在这里，我们利用MXene纳米带作为潜在的电催化剂的析氢反应（HER），考虑12种MXene系统。我们的第一性原理计算表明，MXene纳米带的边缘可以吸附氢物种，并作为析氢的反应位点。带状边缘的结合强度与MXene中金属原子的d带中心相关。特别地，Ti3C2和固溶体（Ti，Nb）C的纳米带表现出高的HER活性，吸附自由能接近于零，塔菲尔势垒分别低于0.42和0.17 eV。低势垒是由于在过渡态中从边缘金属原子到H* 反应物的显著电荷转移。这些理论结果阐明了设计用于具有快速动力学的电催化剂的MXene纳米结构的原理，并阐明了利用具有多种金属元素的MXene进行广泛的电化学反应。
MXenes, a new class of two-dimensional materials, arouse great interest due to their diverse chemistries, superior electrical conductivity and stability. Recently, the nanostructures of MXenes such as nanoribbons and nanodots have been synthesized in experiments, which show peculiar properties and expand the application spectrum of MXenes. Here we exploited MXene nanoribbons as potential electrocatalysts for the hydrogen evolution reaction (HER) by considering 12 kinds of MXene systems. Our first-principles calculations showed that the edges of the MXene nanoribbons can adsorb hydrogen species and serve as the reaction sites for hydrogen evolution. The binding strength of the ribbon edge is correlated with the d band center of metal atoms in MXenes. In particular, the nanoribbons of Ti3C2 and solid solution (Ti,Nb)C exhibit high activity for the HER with the adsorption free energy approaching zero and Tafel barrier below 0.42 and 0.17 eV, respectively. The low barrier is owing to the prominent charge transfer from the edge metal atoms to the H* reactants in the transition state. These theoretical results illuminate the principle for designing MXene nanostructures for electrocatalysts with fast kinetics, and shed light on the utilization of MXenes with more than one metal element for a broad range of electrochemical reactions.