pH-induced morphological transformation of WxMoS2 nanosheets for hydrogen evolution reaction through precursor solution aging

• Published in: Journal of power sources Vol. 526; p. 231154
• Main Authors: Jeffery, A. Anto, Min, Jiho, Kim, Youngjin, Chougule, S.S., Lee, Seunghyun, Jeong, Jong-Ryul, Jung, Namgee
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.04.2022
• Subjects: Edge-exposed layers; Hydrogen evolution reaction; Precursor solution aging; Transition metal dichalcogenide alloy; Two-dimensional transition metal dichalcogenides; Edge-exposed layers; Hydrogen evolution reaction; Precursor solution aging; Transition metal dichalcogenide alloy; Two-dimensional transition metal dichalcogenides
• ISSN: 0378-7753; 1873-2755
• DOI: 10.1016/j.jpowsour.2022.231154

Two-dimensional (2D) transition metal dichalcogenide (TMD) alloy-based nanomaterials are emerging class of hydrogen evolution reaction (HER) catalysts. However, the primary challenges of 2D TMDs is to tune and maximize the concentration of edge-exposed layers with abundant active sites to realize efficient HER catalysis. In this work, we report a simple precursor solution aging-combined hydrothermal route to synthesize high-density edge-exposed WxMoS2 nanosheets. It is demonstrated that progressive aging of the molytungsten precursor solution facilitates the formation of high-density of edge-exposed WxMoS2 layers, strongly influenced by the pH and aging time of precursor solution. In particular, the pH value of solution, which changes with aging time, is the most important factor in converting the morphology of WxMoS2 from 2D nanosheets to self-agglomerated edge-exposed layers and vice versa. Depending on the structural changes, the HER performance of WxMoS2 is rationally modulated, showing the highest activity (η10: 0.209 VRHE and Tafel slope: 46 mV dec−1) when the precursor aging increases by 7 days, but interestingly, further aging again leads to poor HER performance. Accordingly, the systematic study of precursor aging facilitates optimal synthetic conditions that maximize the density of edge-exposed WxMoS2 layers suitable for designing cost-effective and earth-abundant catalysts for industrial applications. [Display omitted] •High-density edge-exposed WxMoS2 layers are achieved by precursor solution aging.•Solution pH changes with aging time and affects the number of edge-exposed layers.•Self-controlled solution pH is a crucial factor in tuning the WxMoS2 nanostructure.•WxMoS2 catalysts formed under intermediate aging conditions show high HER activity.•A surface area-conductivity correlation is unravelled for WxMoS2/C hybrid catalyst.