Unnikrishnan Binesh, Wu Chien-Wei, Sangili Arumugam, Hsu Ya-Ju, Tseng Yu-Ting, Shanker Pandey Jyoti, Chang Huan-Tsung, Huang Chih-Ching
Department of Bioscience and Biotechnology, National Taiwan Ocean University, Keelung 202301, Taiwan.
Department of Chemistry, National Taiwan University, Taipei 10617, Taiwan.
J Colloid Interface Sci. 2022 Dec 15;628(Pt A):849-857. doi: 10.1016/j.jcis.2022.07.176. Epub 2022 Jul 30.
Synthesizing MXenes from MAX (MAX) phases using hazardous hydrogen fluoride is a common and effective method. However, fluorine termination on the basal planes and edges of the resulting MXenes is undesirable for the electrocatalytic hydrogen evolution reaction (HER), while oxygen (O), hydroxyl (OH), and sulfur (S) termination favors this reaction. Herein, we unveil a simple fluorine-free exfoliation and two-step vulcanization method for synthesizing molybdenum sulfide-modified molybdenum carbide (MoS/MoCT MXene, T = OH, O, S) for the HER in alkaline medium. Microwave-assisted hydrothermal treatment of the MAX phase (MoAlC) with sodium hydroxide-sodium sulfide as an etching solution and thioacetamide as a source of sulfide ions enabled the selective dissolution of the aluminum (Al) layer and sulfidation of the surface Mo atoms to form amorphous MoS. Thus, the vulcanization of MoCT MXene resulted in the formation of MoS/MoCT MXene. The MoS formed on the surface of MoCT provided enhanced stability by preventing oxidation. MoS/MoCT exhibited enhanced electrocatalytic activity toward the HER, mainly due to the O, OH, and amorphous MoS functionalities. The MoS sites on the surface exhibited an overpotential of 110 ± 7 mV at a current density of 10 mA cm as a result of enhanced charge transfer and mass transfer. Thus, the sulfidation method demonstrated herein is capable of producing amorphous MoS structures on MoCT MXene, which could be applied for the surface modification of other molybdenum-based nanomaterials or electrocatalysts to improve stability and enhance electrocatalytic activity.
使用危险的氟化氢从MAX相合成MXenes是一种常见且有效的方法。然而，所得MXenes基面和边缘上的氟端基对于电催化析氢反应（HER）是不利的，而氧（O）、羟基（OH）和硫（S）端基则有利于该反应。在此，我们揭示了一种简单的无氟剥离和两步硫化方法，用于合成用于碱性介质中HER的硫化钼修饰的碳化钼（MoS/MoCT MXene，T = OH、O、S）。以氢氧化钠 - 硫化钠为蚀刻溶液，硫代乙酰胺为硫离子源，对MAX相（MoAlC）进行微波辅助水热处理，能够选择性地溶解铝（Al）层并使表面的钼（Mo）原子硫化形成非晶态MoS。因此，MoCT MXene的硫化导致形成MoS/MoCT MXene。在MoCT表面形成的MoS通过防止氧化提供了增强的稳定性。MoS/MoCT对HER表现出增强的电催化活性，主要归因于O、OH和非晶态MoS官能团。由于电荷转移和传质增强，表面的MoS位点在电流密度为10 mA cm时表现出110±7 mV的过电位。因此，本文展示的硫化方法能够在MoCT MXene上制备非晶态MoS结构，这可用于其他钼基纳米材料或电催化剂的表面改性，以提高稳定性并增强电催化活性。
