Surfactant-assisted tungsten sulfide mesoporous sphere for hydrogen production.

Highly proficient, long-lasting non-noble-metal-supported electrocatalysts for hydrogen evolution reaction are important for hydrogen energy production through alkaline electrolyte. In transition metal dichalcogenides, tungsten sulfide is one of the popular materials and is used in a wide variety of applications. In this work, pristine and cationic surfactant assisted tungsten sulfide were successfully synthesized via simple hydrothermal method in alkaline electrolyte for hydrogen evolution reaction. X-ray diffraction confirmed tungsten sulfide rhombohedral structure formation with high index plane (003). Scanning electron microscopy explored tungsten sulfide nanosheet-assembled mesoporous sphere morphology. Tungsten sulfide and cationic surfactant assisted tungsten sulfide overpotential values were found to be 141 and 102 mV at 10 mA/cm2 from linear sweep voltammetry curves. The obtained Tafel slope of tungsten sulfide and cationic surfactant assisted tungsten sulfide were 26.9 and 21.4 mV/dec, respectively. The solution and charge transfer resistance of the prepared materials were obtained from Nyquist plot and found to be 1.7 and 1.4 Ω, and 53.6 and 32 Ω, respectively. The specific surface area, pore diameter, and volume were analyzed by Brunauer–Emmett–Teller method and obtained values for surface area, pore size, and volume of cetyltrimethylammonium bromide assisted tungsten sulfide were 65.05 m2/g, 3.502 nm, and 0.067 cc/g, respectively. The obtained result suggested that 0.1 M cationic surfactant assisted tungsten sulfide showed high catalytic activity with minimum overpotential. Long-term durability studies also suggested that the optimized surfactant-assisted tungsten sulfide had excellent stability over a prolong time of 16 h without any decay. However, the stability of the material exhibited only 90% retention which will improve in our near future works by using carbon-based materials. Hence, carbon-based materials exhibited outstanding chemical stability and offer large surface area, which significantly improves the hydrogen evolution reaction activity and suggests to be used in large-scale applications. [Display omitted] • Tungsten sulfide (WS 2) revealed rhombohedral structure with high index plane (003). • WS 2 surface area, pore size and volume was 65.05 m2/g, 3.502 nm and 0.067 cc/g. • WS 2 explored low 102 mV overpotential with Tafel slope of 21.4 mV/dec. • Cetyltrimethylammonium bromide assisted WS 2 exhibited 90% retention in 16 h CA test. • The optimum concentration of cationic surfactant was fixed as 0.1 M. [ABSTRACT FROM AUTHOR]