Division of Chemistry & Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University , Singapore 637371, Singapore.
ACS Nano. 2014 Dec 23;8(12):12185-98. doi: 10.1021/nn503832j. Epub 2014 Dec 2.
Beyond MoS2 as the first transition metal dichalcogenide (TMD) to have gained recognition as an efficient catalyst for the hydrogen evolution reaction (HER), interest in other TMD nanomaterials is steadily beginning to proliferate. This is particularly true in the field of electrochemistry, with a myriad of emerging applications ranging from catalysis to supercapacitors and solar cells. Despite this rise, current understanding of their electrochemical characteristics is especially lacking. We therefore examine the inherent electroactivities of various chemically exfoliated TMDs (MoSe2, WS2, WSe2) and their implications for sensing and catalysis of the hydrogen evolution and oxygen reduction reactions (ORR). The TMDs studied are found to possess distinctive inherent electroactivities and together with their catalytic effects for the HER are revealed to strongly depend on the chemical exfoliation route and metal-to-chalcogen composition particularly in MoSe2. Despite its inherent activity exhibiting large variations depending on the exfoliation procedure, it is also the most efficient HER catalyst with a low overpotential of -0.36 V vs RHE (at 10 mA cm(-2) current density) and fairly low Tafel slope of ∼65 mV/dec after BuLi exfoliation. In addition, it demonstrates a fast heterogeneous electron transfer rate with a k0obs of 9.17×10(-4) cm s(-1) toward ferrocyanide, better than that seen for conventional glassy carbon electrodes. Knowledge of TMD electrochemistry is essential for the rational development of future applications; inherent TMD activity may potentially limit certain purposes, but intended objectives can nonetheless be achieved by careful selection of TMD compositions and exfoliation methods.
除了作为第一个被认可为高效析氢反应 (HER) 催化剂的过渡金属二卤化物 (TMD) 的 MoS2 之外，人们对其他 TMD 纳米材料的兴趣也在稳步增长。这在电化学领域尤其如此，其中有许多新兴的应用，从催化到超级电容器和太阳能电池都有涉及。尽管这种趋势在上升，但人们对它们电化学特性的理解仍然特别缺乏。因此，我们研究了各种化学剥离 TMD（MoSe2、WS2、WSe2）的固有电化学活性及其对析氢和氧还原反应 (ORR) 的传感和催化的影响。研究发现，这些 TMD 具有独特的固有电化学活性，它们对 HER 的催化作用强烈依赖于化学剥离途径和金属-硫属元素组成，特别是在 MoSe2 中。尽管其固有活性因剥离程序的不同而有很大的变化，但它也是最有效的 HER 催化剂，具有 -0.36 V 相对于 RHE 的低过电势（在 10 mA cm(-2) 电流密度下），并且在 BuLi 剥离后 Tafel 斜率相当低，约为 65 mV/dec。此外，它表现出快速的非均相电子转移速率，对亚铁氰化物的 k0obs 为 9.17×10(-4) cm s(-1)，优于常规玻碳电极。了解 TMD 电化学对于未来应用的合理发展至关重要；固有 TMD 活性可能会限制某些用途，但通过仔细选择 TMD 组成和剥离方法，仍然可以实现预期的目标。
