Enhancement of the Hydrogen Evolution Reaction from Ni-MoS₂ Hybrid Nanoclusters

Abstract

This report focuses on a novel strategy for the preparation of transition metal–MoS2 hybrid nanoclusters based on a one-step, dual-target magnetron sputtering, and gas condensation process demonstrated for Ni-MoS2. Aberration-corrected STEM images coupled with EDX analysis confirms the presence of Ni and MoS2 in the hybrid nanoclusters (average diameter = 5.0 nm, Mo:S ratio = 1:1.8 ± 0.1). The Ni-MoS2 nanoclusters display a 100 mV shift in the hydrogen evolution reaction (HER) onset potential and an almost 3-fold increase in exchange current density compared with the undoped MoS2 nanoclusters, the latter effect in agreement with reported DFT calculations. This activity is only reached after air exposure of the Ni-MoS2 hybrid nanoclusters, suggested by XPS measurements to originate from a Ni dopant atoms oxidation state conversion from metallic to 2+ characteristic of the NiO species active to the HER. Anodic stripping voltammetry (ASV) experiments on the Ni-MoS2 hybrid nanoclusters confirm the presence of Ni-doped edge sites and reveal distinctive electrochemical features associated with both doped Mo-edge and doped S-edge sites which correlate with both their thermodynamic stability and relative abundance.

Electrocatalytic Water Splitting and CO2 Reduction: Sustainable Solutions via Single‐Atom Catalysts Supported on 2D Materials

“…Comparing the undoped MoS 2 and Ni‐doped MoS 2 in terms of Tafel slopes, the Ni doping could not decrease the Tafel slope value significantly, leaving the HER mechanism unchanged as reported previously . The measurement of the thermodynamic stability using anodic stripping voltammetry reveals that the undoped and doped edge sites are electrochemically distinguishable following the order Ni‐doped Mo edge < Ni‐doped S edge < pristine Mo edge …”

“…in the S edge sites, resulting in the Δ G H value shifts close to zero. Palmer and his group reported a novel approach to prepare Ni‐doped MoS 2 NPs (Ni–MoS 2 NPs) via a one‐step, dual‐target, and magnetron sputtering technique . AC‐STEM images coupled with EDS analysis confirm the existence of Ni atoms and MoS 2 in their hybrid nanoclusters with 5 nm average diameters.…”

“…d) Tafel plots (η vs log| j geom |) of the Ni‐doped/undoped MoS 2 nanoclusters. Reproduced with permission . Copyright 2017, Wiley‐VCH.…”

Modification of Deposited, Size-Selected MoS2 Nanoclusters by Sulphur Addition: An Aberration-Corrected STEM Study

“…The HAADF intensity distribution (Figure 1c) measured from 155 independent clusters indicates several peaks in the size spectrum. In order to confirm which peak corresponds to the original (MoS 2 ) 1000 clusters, the size of the cluster shown in Figure 1d was derived from Mo atom counting [22,28]. This cluster was found to contain approximately 1100 Mo atoms and is located in peak 3.…”

Phosphorus‐Doped MoS2 Nanosheets Supported on Carbon Cloths as Efficient Hydrogen‐Generation Electrocatalysts

“…On the other hand, controllable disorder engineering has also been demonstrated in oxygen‐incorporated MoS 2 ultrathin nanosheets for efficient hydrogen evolution . Furthermore, interface engineering on the surface of nanostructured MoS 2 by building a heterogeneous catalyst is also well established to increase the number of surface active sites and, correspondingly, to improve the catalytic properties . Recently, doping engineering has also been proved as a very effective technique to create active catalytic sites on MoS 2 nanosheets.…”