CVD-Grown MoSe₂ Nanoflowers with Dual Active Sites for Efficient Electrochemical Hydrogen Evolution Reaction

Abstract

Due to its unique electronic band characteristics (presence of d-orbital in both Mo and Se atoms), MoSe has potential to exhibit high electrical conductivity and superior hydrogen evolution reaction (HER) kinetics when compared to other transition-metal dichalcogenides. Though various strategies were employed earlier to obtain MoSe structure with different shapes and morphologies, precise control on achieving both Mo- and Se-edge sites and understanding their interaction with reactants in HER remains to be challenging. Here, we successfully demonstrate the vapor diffusion method to grow highly crystalline MoSe nanoflowers on carbon cloth in a vertical orientation. Uniformly dispersed nanoflowers with Mo- and Se-edge sites exhibited remarkable electrocatalytic activity on hydrogen reduction in terms of low Tafel slope and high exchange current density. The existence of a strong interaction between MoSe and carbon cloth assists in long-term hydrogen production and confirms the exceptional durability of the catalyst. A comprehensive evidence for hydrogen adsorption on dual active sites, viz., Mo- and Se-edges of MoSe, is provided using X-ray photoelectron spectroscopy and in situ Raman spectroscopy containing a specially designed liquid immersion objective lens.

Two-Dimensional MoS2: Structural Properties, Synthesis Methods, and Regulation Strategies toward Oxygen Reduction

“…More importantly, there are unsaturated coordination and dangling bonds at the edges of TMDs nanosheets. These special properties of TMDs nanosheets provide many inspirations for basic research in many fields including catalysis [28][29][30][31][32][33], transistor [34], energy storage [35][36][37][38][39] and sensor [40][41][42]. Among all 2D TMDs, MoS 2 is one of the few with a natural layered structure, indicating that MoS 2 can be stripped to obtain high-quality 2D MoS 2 without complicated chemical synthesis [26].…”

Controlled Growth of Edge‐Enriched ReS2 Nanoflowers on Carbon Cloth Using Chemical Vapor Deposition for Hydrogen Evolution

“…This is because that the edge density obtained at a certain temperature is determined by the available amount of precursors, which is delivered by the carrier gas. [56,57] The density and crystal size can be significantly raised by elevating gas flow rate through delivering more sulfur to the reaction region. Simultaneously, the increased edge density induced the improved catalytic activity.…”

Defect Engineering of van der Waals Solids for Electrocatalytic Hydrogen Evolution

“…In addition, Ling et al [45] fabricated the highly curved MoS 2 nanopetals vertically arranged on carbon nanotubes films through the spiral growth mechanism, which exposed numerous edges sites along with the large surface areas, leading to an enhanced HER activity (η: 100 mV and Tafel slope: 49.5 mV dec À 1 ). Masurkar et al [41] designed a vapor diffusion method to vertically grow high-crystalline MoSe 2 nanoflowers onto the carbon cloth (MoSe 2 /CC) (Figure 5b). On the one hand, the MoSe 2 nanoflowers consisted of multilayer nanosheets perpendicular to the substrate, generating abundant unsaturated active edge sites.…”

“…(c) The polarization curves of MoSe 2 nanoflowers grown on CC. [41] (d) The schematic of mesoporous MoS 2 with double-gyroid (DG) morphology. [42] (e) The schematic of the MoS 2 dendritic flakes grown on SrTiO 3 (001) substrate.…”

“…(b) Scanning electron microscopy (SEM) image of MoSe 2 nanoflowers grown on carbon cloth (CC) at 850 °C. (c) The polarization curves of MoSe 2 nanoflowers grown on CC [41] . (d) The schematic of mesoporous MoS 2 with double‐gyroid (DG) morphology [42] .…”