Electrosynthesis of Bifunctional WS_3−x/Reduced Graphene Oxide Hybrid for Hydrogen Evolution Reaction and Oxygen Reduction Reaction Electrocatalysis

Abstract

A multitude of research into the application of transition-metal dichalcogenides as earth-abundant hydrogen evolution reaction (HER) electrocatalysts has been conducted. However, current synthetic methods generally deploy environmentally harmful chemicals and energy-consuming reaction conditions, despite the primary intent to attain renewable energy production. Here, the desirable properties of tungsten sulfide and reduced graphene oxide (rGO) have been combined and hybrid materials have been fabricated through simultaneous electrochemical reduction and synthesis, as a versatile and environmentally benign alternative to conventional fabrication techniques. Through concurrent studies of three rGO materials, the precursor of which was graphene oxide (GO), produced by Hummers, Staudenmaier, or Hofmann oxidation methods, the importance of the choice of oxidation method employed prior to the fabrication of the hybrid was shown. In this cardinal study, a mixed WS /WS film-like material (WS ) was synthesized directly onto GO-modified glassy carbon electrodes by cyclic voltammetry and the resultant hybrid materials (WS /rGO) were thoroughly characterized by SEM, energy-dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy, and Raman spectroscopy. The excellent bifunctional electrocatalytic performances of WS /rGO towards both HER and oxygen reduction reaction stemmed from the coupled impacts of amplified electrical conductivity and surface area of rGO; the presence of metallic species within rGO, resulting from the oxidation process; and the amount of WS successfully electrodeposited in the hybrid. The efficacious fabrication of the WS /rGO composite through electrosynthesis reveals an innovative and eco-friendly methodology for the development of cost-effective and highly active bifunctional electrocatalysts for renewable energy generation.

Reduced graphene oxide‐based materials for electrochemical energy conversion reactions

“…Groups of transition metal compounds that have electrochemical activity for HER and OER are often effective in the ORR reaction in many cases . Transition metal oxides are frequently used in ORR reactions with the help of rGO despite the disadvantages of their low conductivity and deficient active sites.…”

“…Transition metal sulfides, the attractive materials especially for water splitting, are also effective to ORR when combined with rGO . Gautam et al reported that a FeS anchored rGO hybrid nanocomposites exhibited a remarkably improved catalytic performance for ORR.…”

The Role of Sulfur-Related Species in Oxygen Reduction Reactions

“…The novel electrocatalysts showed enhanced performance for ORR, due to their strong interaction between MoS 2 and carbon layer, high conductivity, and high specific surface area. Recently, it has been reported that Ni 3 S 2 [36] and WS 3−x [37] are also potential catalyst for ORR. Furthermore, metallic double sulfides as an ORR catalyst were investigated in recent years.…”

Ultrasmall MoS3 Loaded GO Nanocomposites as High‐Rate and Long‐Cycle‐Life Anode Materials for Lithium‐ and Sodium‐Ion Batteries

“…Among these anode materials, metal sulfides as anode materials are one kind of promising candidates due to the high specific capacities, and molybdenum based sulfides have been widely investigated for both LIBs and SIBs owing to their peculiar structure merits . Besides layered MoS 2 , MoS 3 have aroused great attention due to its special structure . As potential anode material, MoS 3 has many merits: First, it has one dimensional chain‐like structure, with more open sites to storage more Li + or Na + during the electrochemical reaction, which can provide higher specific capacity.…”

“…[23][24][25][26][27][28] Besides layered MoS 2 , MoS 3 have aroused great attention due to its special structure. [29][30][31][32] As potential anode material, MoS 3 has many merits: First, it has one dimensional chain-like structure, [29] with more open sites to storage more Li + or Na + during the electrochemical reaction, which can provide higher specific capacity. Second, its high conductivity can improve the electron transfer efficiency.…”