MoS(2) with Controlled Thickness for Electrocatalytic Hydrogen Evolution.

Molybdenum disulfide (MoS2) has moderate hydrogen adsorption free energy, making it an excellent alternative to replace noble metals as hydrogen evolution reaction (HER) catalysts. The thickness of MoS2 can affect its energy band structure and interface engineering, which are the avenue way to adjust HER performance. In this work, MoS2 films with different thicknesses were directly grown on the glassy carbon (GC) substrate by atomic layer deposition (ALD). The thickness of the MoS2 films can be precisely controlled by regulating the number of ALD cycles. The prepared MoS2/GC was directly used as the HER catalyst without a binder. The experimental results show that MoS2 with 200-ALD cycles (the thickness of 14.9 nm) has the best HER performance. Excessive thickness of MoS2 films not only lead to the aggregation of dense MoS2 nanosheets, resulting in reduction of active sites, but also lead to the increase of electrical resistance, reducing the electron transfer rate. MoS2 grown layer by layer on the substrate by ALD technology also significantly improves the bonding force between MoS2 and the substrate, showing excellent HER stability.

二硫化钼（MoS₂）具有适中的氢吸附自由能，使其成为替代贵金属作为析氢反应（HER）催化剂的绝佳选择。MoS₂的厚度会影响其能带结构和界面工程，这是调节HER性能的途径。在这项工作中，通过原子层沉积（ALD）在玻碳（GC）基底上直接生长了不同厚度的MoS₂薄膜。通过调节ALD循环次数可以精确控制MoS₂薄膜的厚度。制备的MoS₂/GC在没有粘结剂的情况下直接用作HER催化剂。实验结果表明，经过200次ALD循环（厚度为14.9 nm）的MoS₂具有最佳的HER性能。MoS₂薄膜过厚不仅会导致致密的MoS₂纳米片聚集，从而使活性位点减少，还会导致电阻增加，降低电子转移速率。通过ALD技术在基底上逐层生长的MoS₂还显著提高了MoS₂与基底之间的结合力，表现出优异的HER稳定性。