Single-Crystalline Mo-Nanowire-Mediated Directional Growth of High-Index-Faceted MoNi Electrocatalyst for Ultralong-Term Alkaline Hydrogen Evolution
Single-Crystalline Mo-Nanowire-Mediated Directional Growth of High-Index-Faceted MoNi Electrocatalyst for Ultralong-Term Alkaline Hydrogen Evolution
复制标题
单晶钼纳米线介导的高折射率面 MoNi 电催化剂定向生长用于超长期碱性析氢
DOI：
10.1021/acsami.0c11716
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发表时间：
2020-08-12
影响因子：
9.5
通讯作者：
Zhang, Jian
中科院分区：
文献类型：
--
作者：
Liu, Zhenpeng;Zhang, Guoxian;Zhang, Jian
富含稀土的MoNi基电催化剂作为碱性电解槽中催化析氢反应(HER)的贵金属基电催化剂，受到了广泛的关注。不幸的是，寻找具有优异的本征活性和超长期稳定性的MoNi基电催化剂仍然是一个巨大的挑战。本文通过MoNiMoO(4)核壳纳米线的热还原，通过局域化学方法合成了超长的高折射率刻面Mo@MoNi核壳纳米线，其中单晶Mo的负载促进了NiMoO4向高折射率刻面MoNi的拓扑转变。在碱性溶液中制备的Mo@MoNi核壳纳米线膜作为独立阴极，在10 mA cm(-2)时的过电位为18 mV，Tafel斜率与33 mV dec(-1)相近，远低于目前最先进的富土电催化剂，甚至低于商用的铂/C。实验和理论研究表明，暴露的高指数(331)面的MoNi能显著降低初始水解离和随后的氢结合步骤的能垒，从而协同加速了迟滞的碱性HER动力学。值得注意的是，经过70天的HER运行，Mo@MoNi电催化剂在10 mA cm(-2)处的过电位仅降低了4 mV。因此，本工作对高性能HER电催化剂的合理设计及其在碱性电解槽中的实际应用具有重要意义。
As appealing alternatives to noble-metal-based electrocatalysts for catalyzing hydrogen evolution reaction (HER) in alkali electrolyzers, earth-abundant MoNi-based catalysts have attracted intensive attention. Unfortunately, the exploration of MoNi-based electrocatalysts with superior intrinsic activity and ultralong-term stability still remains a grand challenge. Here, ultralong high-index faceted Mo@MoNi core-shell nanowires were topochemically synthesized through the thermal reduction of MogNiMoO(4) core-shell nanowires, where single-crystalline Mo support facilitates the topological transformation of NiMoO4 into high-index faceted MoNi. When the as-achieved Mo@MoNi core-shell nanowire film serve as a free-standing cathode in alkaline solutions, it exhibit a remarkably decreased HER overpotential of 18 mV at 10 mA cm(-2) and a Tafel slope of similar to 33 mV dec(-1), which are much lower than those for the state-of-the-art earth-abundant electrocatalysts and even commercial Pt/C. Experimental and theoretical investigations reveal that the exposed high-index (331) facets of MoNi can considerably reduce the energy barriers of initial water dissociation and subsequent hydrogen combination steps, which synergistically accelerates the sluggish alkaline HER kinetics. Significantly, after a 70-day HER operation, the overpotential of Mo@MoNi electrocatalysts at 10 mA cm(-2) decreases by only 4 mV. Therefore, this work sheds a bright light on the rational design of high-performance HER electrocatalysts and their practical utilization for alkaline electrolyzers.