Abstract
Nano-structured molybdenum disulfide (MoS2) catalysts have been extensively developed for the hydrogen evolution reaction (HER). Herein, a novel hydrothermal intercalation approach is employed to fabricate nanoflower-like 2H–MoS2 with the incorporation of three polymers, polyvinylpyrrolidone (PVP), polyvinyl alcohol (PVA), and polyethylenimine (PEI). The as-prepared MoS2 specimens were characterized by techniques of scanning electron microscope (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), together with Raman and Fourier transform infrared spectroscopy (FTIR). The HER properties of these lamellar nanoflower-like composites were evaluated using electrochemical tests of linear sweep voltammetry (LSV) and electrochemical impedance spectroscopy (EIS). The existent polymer enlarges the interlayer spacing of the lamellar MoS2, and reduces its stacked thickness. The lamellar MoS2 samples exhibit a promoting activity in HER at low additions of these three polymers (0.04 g/g MoS2 for PVA and PEI, and 0.08 g/g MoS2 for PVP). This can be attributed to the fact that the expanded interlayer of MoS2 can offer abundant exposed active sites for HER. Conversely, high additions of the polymers exert an obvious interference in the HER activity of the lamellar MoS2. Compared with the samples of MoS2/PVP–0.08 and MoS2/PEI–0.04, the MoS2/PVA–0.04 composite exhibits excellent activity in HER, in terms of higher current density and lower onset potential.
Highlights
Hydrogen as an ideal, clean and efficient secondary energy resource serves as one of the most competent candidates for replacing petroleum fuels for the future
A variety of nonmetal and metal materials such as carbides [3,4], and Pt-group alloys [5,6] employed as catalysts for the hydrogen evolution reduction (HER) have been extensively explored
The aim of this study is to reveal the effects of intercalated polymers on the structure, density of active edge sites, and HER activity of nanoflower-like MoS2
Summary
Clean and efficient secondary energy resource serves as one of the most competent candidates for replacing petroleum fuels for the future. The suitability of MoS2 as an excellent catalyst for HER, is mainly due to the catalytic activity at the edge of this lamellar crystal [7,12,13]. It has been proved by theoretical and experimental studies that the active sites of 2H-MoS2 for HER locate the (010) and (100) planes with the existence of unsaturated molybdenum and sulfur atoms, while the (002) basal plane is inactive [7,12,14]
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