Size-Dependent Enhancement of Electrocatalytic Oxygen-Reduction and Hydrogen-Evolution Performance of MoS2 Particles
Size-Dependent Enhancement of Electrocatalytic Oxygen-Reduction and Hydrogen-Evolution Performance of MoS2 Particles
复制标题
MoS2颗粒电催化氧还原和析氢性能的尺寸依赖性增强
DOI：
10.1002/chem.201301406
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发表时间：
2013-09-02
影响因子：
4.3
通讯作者：
Li, Meixian
中科院分区：
文献类型：
--
作者：
Wang, Tanyuan;Gao, Dongliang;Li, Meixian
以块状MoS2为原料，通过简单的超声处理和梯度离心法制备了不同粒度分布的MoS2颗粒。相对于惰性微米级MoS_2，纳米级MoS_2对氧还原反应(ORR)和析氢反应(HER)的催化活性显著提高。颗粒尺寸的减小伴随着催化活性的提高。与标准氢电极(SHE)相比，尺寸在2 nm左右的粒子表现出最好的双重ORR和她的性能，采用四电子ORR过程，HER起始电位为-0.16V。这是首次研究了MoS_2的ORR活性的尺寸效应，发现了四电子转移途径。结果表明，MoS_2纳米颗粒暴露出丰富的Mo边是其具有较高的催化活性的原因，而纳米颗粒HER活性的提高归因于大量暴露的S边。这一新发现的工艺提供了一种简单的方案来生产廉价、高活性的MoS2催化剂，这种催化剂很容易放大。因此，它为MoS_2纳米粒子在能量转换和存储领域的广泛应用开辟了可能性。
MoS2 particles with different size distributions were prepared by simple ultrasonication of bulk MoS2 followed by gradient centrifugation. Relative to the inert microscale MoS2, nanoscale MoS2 showed significantly improved catalytic activity toward the oxygen-reduction reaction (ORR) and hydrogen-evolution reaction (HER). The decrease in particle size was accompanied by an increase in catalytic activity. Particles with a size of around 2nm exhibited the best dual ORR and HER performance with a four-electron ORR process and an HER onset potential of -0.16V versus the standard hydrogen electrode (SHE). This is the first investigation on the size-dependent effect of the ORR activity of MoS2, and a four-electron transfer route was found. The exposed abundant Mo edges of the MoS2 nanoparticles were proven to be responsible for the high ORR catalytic activity, whereas the origin of the improved HER activity of the nanoparticles was attributed to the plentiful exposed S edges. This newly discovered process provides a simple protocol to produce inexpensive highly active MoS2 catalysts that could easily be scaled up. Hence, it opens up possibilities for wide applications of MoS2 nanoparticles in the fields of energy conversion and storage.