Abstract
The effects of glucose on the growth and surface properties of MoS with nanosheet structure were investigated in detail. In the presence of glucose, the hydrothermal reaction of sodium molybdate and thiourea yields carbon-loaded MoS nanocomposites (C/MoS). Compared with bare MoS nanosheets with more than six layers obtained in the absence of glucose and carbon spheres with diameter of 500 nm prepared from the carbonization of glucose, C/MoS consist of one or three layered MoS and carbon spheres with diameter less than 1 nm to give large BET surface area (3~20 times larger than the individual materials). The surface characterizations reveal that both MoS and carbon spheres of C/MoS have negative charge on the surface, suggesting that the previously reported explanation, in which the adsorption of MoS and/or molybdate ions on carbon spheres inhibits the growth and aggregation of MoS, is not correct. Based on FT-IR and H NMR spectra, it is demonstrated that glucose acts as the hydrogen bond donor toward polyoxomolybdate species such as MoO, MoO, and MoO in the range of pH = 2 - 12. The intermolecular hydrogen bond not only inhibits the growth of both (002) plane of MoS and carbon spheres, but also enables the formation of C-O-Mo bonds in the in situ generated C/MoS. Compared with bare MoS, C/MoS not only show a lower over-potential by 60 mV for the electrocatalytic evolution of hydrogen, but also has a larger mass specific capacitance by three times, due to the larger surface area and the interfacial interaction through C-O-Mo bonds.
Citation
ID:
31394
Ref Key:
wang2019hydrogenacs