Low Overpotential in Vacancy-Rich Ultrathin CoSe2 Nanosheets for Water Oxidation
Low Overpotential in Vacancy-Rich Ultrathin CoSe2 Nanosheets for Water Oxidation
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富含空位的超薄 CoSe2 纳米片用于水氧化的低过电势
DOI：
10.1021/ja5085157
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发表时间：
2014-11-05
影响因子：
15
通讯作者：
Xie, Yi
中科院分区：
文献类型：
--
作者：
Liu, Youwen;Cheng, Hao;Xie, Yi
根据Yang Shao-Horns原理，CoSe 2是一种有希望的候选者，作为一种高效，负担得起的，可持续的替代电催化剂用于析氧反应，由于其非常适合的Co离子的电子构型。然而，纯CoSe 2的催化效率仍然远低于预期，因为其活性位点暴露产率差。在本文中，我们成功地克服了散装CoSe 2中活性位点不足的缺点，通过将其厚度减小到原子尺度，而不是任何额外的修饰（例如掺杂或与石墨烯或贵金属杂交）。正电子湮没谱和XAFS谱提供了明确的证据，大量的VCo？在纳米片中形成空位。第一性原理计算表明，这些VCo？在pH 13的介质中，10 mA cm（-2）时的OER过电位低至0.32 V，这一结果上级于其本体催化剂和大多数报道的Co基电催化剂。考虑到简单的未改性的CoSe 2纳米片作为唯一催化剂的出色性能，当使用掺杂或杂化的各种策略时，预期催化活性的进一步改善。这些结果不仅证明了一个显着的，负担得起的，和地球丰富的水氧化电催化剂的基础上的CoSe 2纳米片的潜力，但也开辟了一个有前途的途径，探索优秀的活性和耐用的催化剂，以取代贵金属的氧电催化。
According to Yang Shao-Horns principle, CoSe2 is a promising candidate as an efficient, affordable, and sustainable alternative electrocatalyst for the oxygen evolution reaction, owing to its well-suited electronic configuration of Co ions. However, the catalytic efficiency of pure CoSe2 is still far below what is expected, because of its poor active site exposure yield. Herein, we successfully overcome the disadvantage of insufficient active sites in bulk CoSe2 by reducing its thickness into the atomic scale rather than any additional modification (such as doping or hybridizing with graphene or noble metals). The positron annihilation spectrometry and XAFS spectra provide clear evidence that a large number of VCo? vacancies formed in the ultrathin nanosheets. The first-principles calculations reveal that these VCo? vacancies can serve as active sites to efficiently catalyze the oxygen evolution reaction, manifesting an OER overpotential as low as 0.32 V at 10 mA cm(-2) in pH 13 medium, which is superior to the values for its bulk counterparts as well as those for the most reported Co-based electrocatalysts. Considering the outstanding performance of the simple, unmodified ultrathin CoSe2 nanosheets as the only catalyst, further improvement of the catalytic activity is expected when various strategies of doping or hybridizing are used. These results not only demonstrate the potential of a notable, affordable, and earth-abundant water oxidation electrocatalyst based on ultrathin CoSe2 nanosheets but also open up a promising avenue into the exploration of excellent active and durable catalysts toward replacing noble metals for oxygen electrocatalysis.