Constructing carbon-cohered high-index (222) faceted tantalum carbide nanocrystals as a robust hydrogen evolution catalyst
Constructing carbon-cohered high-index (222) faceted tantalum carbide nanocrystals as a robust hydrogen evolution catalyst
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DOI：
10.1016/j.nanoen.2017.04.057
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发表时间：
2017-06
期刊：
影响因子：
17.6
通讯作者：
Zongkui Kou;Kai Xi;Zonghua Pu;Shichun Mu
中科院分区：
文献类型：
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作者：
Zongkui Kou;Kai Xi;Zonghua Pu;Shichun Mu
由于缺乏活性中心，纳米V族金属碳化物(如TaC)的电催化作用几乎没有受到足够的重视。我们的理论计算表明，TAC的高指数(222)晶面比其他晶面在析氢反应(HER)方面要活跃得多。然而，暴露的高指数(222)面的容易演化给制造带来了巨大的挑战。在这里，为了获得碳共聚的高指数(222)面碳化钽纳米晶(TaC NCS@C)，我们首先开发了一种新的氯辅助的“微切割-破碎”技术，通过对块体TAC进行不完全氯化。有趣的是，利用原位生成的碳层和(222)面之间的过渡区，可以在制备和电化学反应过程中阻止具有高表面能的高指数(222)面的演化。作为HER催化剂，TAC NCS@C在10 mA/cm-2时表现出~146 mV的低过电位，9.69×10-2 mA/cm-2的大交换电流密度，以及出色的长期循环性能。据我们所知，她的这一性能远远优于已报道的V族金属碳化物基催化剂。鉴于该方法具有很强的通用性，可广泛应用于制备其他原位碳化装甲高指数面金属碳化物纳米晶。
The electrocatalysis of nanoscale group V metal carbides (e.g. TaC) has almost received far less attentions owing to lack of active sites. Our theoretical calculations show that high-index (222) facets of TaC are dramatically more active than its other facets towards hydrogen evolution reaction (HER). However, the easy evolution of exposed high-index (222) facets causes a big challenge in fabrication. Here, to obtain the carbon-cohered high-index (222) faceted tantalum carbide nanocrystals (TaC NCs@C), we first develop a novel chlorine-assisted “micro-cutting-fragmentation” technique by incomplete chlorination towards bulk TaC. Interestingly, benefiting from transition zones between in situ formed carbon layers and (222) facets, the evolution of high-index (222) facets with high surface energy can be prevented during the preparation and electrochemical reaction. When evaluated as a HER catalyst, TaC NCs@C presents a low overpotential of ~146 mV at 10 mA cm-2, a large exchange current density of 9.69×10-2mA cm-2and outstanding long-term cycling performance. To the best of our knowledge, this HER performance is far preferable to that of the reported group V metal carbides-based catalysts. In the light of the highly generic nature, the methodology developed in this study can be widely applied to produce other in situ carbon armored high-index faceted metal carbide nanocrystals.