One-Step Surface-Plasma-Induced Exfoliation of the Graphite/WS₂ Bilayer into Homogeneous Two-Dimensional Graphene/WS₂ Nanosheet Composites as Catalysts for the Hydrogen Evolution Reaction

Abstract

In this paper, a unique method for one-step surface-plasma-induced exfoliation of a graphite/bulk transitional-metal dichalcogenide (TMD) bilayer for the preparation of graphene (Gs)/TMD nanosheet composites is presented, using Gs−tungsten disulfide (WS 2 ) nanocomposites that functioned as electrocatalysts for the hydrogen evolution reaction (HER) as our case study. This approach of producing nanocomposites is universal for all TMD materials with a graphite substrate layer that generates surface plasma when serving as the cathode under 65 V in a 1 M H 2 SO 4 or KOH electrolyte at 90 °C for 50 min. After characterizing the resultant binary nanocomposites, we found that the optimal HER performance occurred for the resultant binary nanocomposites (GW3−H 2 SO 4 ) that is produced from a graphite/bulk WS 2 bilayer (thickness ratio 0.13:0.03 mm) with 1 M H 2 SO 4 as the electrolyte; it has a low overpotential of 180 mV at a current density of 10 mA cm −2 with a low Tafel slope of 76 mV dec −1 and with high stability up to 30 h. This cost-effective and scalable one-step techniquecombining two dissimilar two-dimensional nanostructured compositesfor electrocatalytic applications appears to be an efficient means of fabricating Gs/TMD nanosheet composites suitable for use as HER electrocatalysts.

Hydrothermally Derived Hierarchical CuO Nanoflowers as an Efficient Photocatalyst and Electrocatalyst for Hydrogen Evolution

“…The attained onset potential of as‐synthesized CuO nanoflowers was found to be in proximity to the onset potential of iridium oxide electrocatalyst which is known to be the standard of electrocatalytic water splitting for oxygen evolution. The mechanism and reaction kinetics for electrocatalytic HER and OER responses were investigated by employing Tafel equation [7,36] . Figure 10 (c) and (d) shows the Tafel plots of as‐prepared CuO nanoflowers for HER and OER reactions, respectively.…”

Two-Dimensional NH4V3O8 Nanoflakes as Efficient Energy Conversion and Storage Materials for the Hydrogen Evolution Reaction and Supercapacitors

“…Moreover, the electrode kinetics of the NH 4 V 3 O 8 nanoflake material was also investigated using EIS measurements, as shown in Figure c. The equivalent series resistance ( R S ) and charge-transfer resistance ( R CT ) were 12 and 112 Ω (Figure S3 and Table S1), respectively, indicating the high electrical conductivity, highly conductive electrode–electrolyte interface, and good internal resistance of NH 4 V 3 O 8 nanoflakes, which make them an excellent HER catalyst . The i – t curves of NH 4 V 3 O 8 -modified glassy carbon electrodes at −10 mA cm –2 after 48 h of chronoamperometry measurement shown in Figure d suggest the good stability of NH 4 V 3 O 8 for HER.…”

Computation and Investigation of Two-Dimensional WO3·H2O Nanoflowers for Electrochemical Studies of Energy Conversion and Storage Applications

“…The electrochemical potential was calibrated with reversible hydrogen electrodeby equation: E RHE = E SCE + 0.209 + 0.0591pH = 0.23. From LSV plots, we can calculate the Tafel plots which correspond to the inherent properties of the catalysts by using the Tafel equation: 41 where η , b , j , and a are the overpotential, Tafel slope, current density, and a constant, respectively.…”