The rational design of transition metal dichalcogenide electrocatalysts for efficiently catalyzing the hydrogen evolution reaction (HER) is believed to lead to the generation of a renewable energy carrier. To this end, our work has made three main contributions. At first, we have demonstrated that exfoliation via ionic liquid assisted grinding combined with gradient centrifugation is an efficient method to exfoliate bulk WS₂ to nanosheets with a thickness of a few atomic layers and lateral size dimensions in the range of 100 nm to 2 nm. These WS₂ nanosheets decorated with scattered nanodots exhibited highly enhanced catalytic performance for HER with an onset potential of −130 mV vs. RHE, an overpotential of 337 mV at 10 mA cm⁻² and a Tafel slope of 80 mV dec⁻¹ in 0.5 M H₂SO₄. Secondly, we found a strong aging effect on the electrocatalytic performance of WS₂ stored in high boiling point organic solvents such as dimethylformamide (DMF). Importantly, the HER ability could be recovered by removing the organic (DMF) residues, which obstructed the electron transport, with acetone. Thirdly, we established that the HER performance of WS₂ nanosheets/nanodots could be significantly enhanced by activating the electrode surface at a positive voltage for a very short time (60 s), decreasing the kinetic overpotential by more than 80 mV at 10 mA cm⁻². The performance enhancement was found to arise primarily from the ability of a formed proton-intercalated amorphous tungsten trioxide (a-WO₃) to provide additional active sites and favourably modify the immediate chemical environment of the WS₂ catalyst, rendering it more favorable for local proton delivery and/or transport to the active edge site of WS₂. Our results provide new insights into the effects of organic solvents and electrochemical activation on the catalytic performance of two-dimensional WS₂ for HER.

中文翻译：

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剥落，有机溶剂和阳极活化对二硫化钨催化放氢反应的影响

合理设计用于有效催化氢释放反应（HER）的过渡金属二硫化氢电催化剂，可导致产生可再生能源载体。为此，我们的工作做出了三项主要贡献。首先，我们证明了通过离子液体辅助研磨与梯度离心相结合进行剥落是一种有效的方法，可将大量WS ₂剥落为厚度为几个原子层且横向尺寸范围为100 nm至2 nm的纳米片。这些用分散的纳米点装饰的WS ₂纳米片对HER的催化性能大大增强，相对于RHE的起始电位为-130 mV ，在10 mA cm时的超电位为337 mV^-2和0.5 MH ₂ SO _4中的Tafel斜率为80 mV dec ^-1。其次，我们发现在高沸点有机溶剂（如二甲基甲酰胺（DMF））中存储的WS ₂的电催化性能具有很强的老化作用。重要的是，可以通过用丙酮去除阻碍电子传输的有机（DMF）残基来恢复HER能力。第三，我们确定可以通过在非常短的时间内（60 s）以正电压激活电极表面，在10 mA cm处将动力学过电势降低80 mV以上，从而显着提高WS ₂纳米片/纳米粒子的HER性能。 ⁻²。发现性能增强主要是由于形成的质子插层的无定形三氧化钨（a-WO ₃）提供额外的活性位点并有利地改变WS ₂催化剂的直接化学环境的能力，从而使其更适合局部使用。质子传递和/或运输到WS ₂的活动边缘站点。我们的结果为有机溶剂和电化学活化对二维WS ₂对HER的催化性能的影响提供了新的见解。