Controlled Synthesis of Ni‐Doped MoS₂ Hybrid Electrode for Synergistically Enhanced Water‐Splitting Process

Abstract

The development of high-efficiency,l ow-cost, and earth-abundant electrocatalysts for overall water splitting remains achallenge. In this work, Ni-modified MoS 2 hybrid catalysts are grown on carbon cloth (Ni-Mo-S@CC) through a one-step hydrothermalt reatment. The optimized Ni-Mo-S@CC catalyst shows excellent hydrogen evolution reaction (HER) activity with al ow overpotential of 168 mV at ac urrent density of 10 mA cm À2 in 1.0 m KOH, which is lower than those of Ni-Mo-S@CC( 1:1),N i-Mo-S@CC (3:1), and pure MoS 2 .S ignificantly,t he Ni-Mo-S@CC hybrid catalyst also displays outstanding oxygen evolutionr eaction( OER) activity with al ow overpotential of 320 mV at ac urrent density of 10 mA cm À2 ,a nd remarkable long-term stabilityf or 30 ha ta constant currentd ensity of 10 mA cm À2 .E xperimental results and theoretical analysis based on density functional theory demonstrate that the excellent electrocatalytic performance can be attributed mainlyt ot he remarkablec onductivity, abundant active sites, and synergistic effect of the Ni-doped MoS 2 .T his work sheds light on au nique strategy for the designo fh igh-performance and stable electrocatalysts for water-splitting electrolyzers.

Insights into the Mo-Doping Effect on the Electrocatalytic Performance of Hierarchical CoxMoyS Nanosheet Arrays for Hydrogen Generation and Urea Oxidation

“…All the Co x Mo y S-CC composites display lower overpotentials than CoS 2 -CC, and the η 10 (the overpotential at 10 mA/cm 2 ) has the following order: Co 3 Mo 1 S-CC (85 mV) < Co 1 Mo 1 S-CC (111 mV) < Co 5 Mo 1 S-CC (114 mV) < Co 1 Mo 3 S-CC (133 mV) < CoS 2 -CC (138 mV). Clearly, although the Co 3 Mo 1 S-CC catalyst shows lower HER activity than the precious metal Pt/C catalyst, it exhibits the best activity among the studied Co x Mo y S-CC samples, and such activity is also superior to most of the reported HER electrocatalysts, as summarized in Table S1. ,,− ,,,,− ,,,− Such result illustrates that the Mo-doping-induced electronic structure change can significantly heighten the HER activity of CoS 2 nanosheets.…”

“…For electrocatalysts, combining active materials with conductive and robust substrates, e.g., carbon cloth and metal foam, can provide more accessible sites, enhance the electron-transfer process, and improve the mechanical strength. − The self-supporting materials can be used as working electrodes directly, and they can provide larger surface areas than solid electrodes, which is conducive to the diffusion of gas. Also, in situ growth of nanosheets on carbon cloth eliminates the influence of binder on the transport of electrolyte in the active materials and the contact resistance between the active materials and the substrate. , Based on the above considerations, we report here a series of bifunctional nanostructured metal sulfide electrocatalysts, with Co x Mo y S nanosheets supported on carbon cloth (Co x Mo y S-CC). The fabricated Co x Mo y S-CC with an optimized composition and structure exhibited high HER and UOR catalytic performances in alkaline conditions.…”

“…Also, in situ growth of nanosheets on carbon cloth eliminates the influence of binder on the transport of electrolyte in the active materials and the contact resistance between the active materials and the substrate. 42,43 Based on the above considerations, we report here a series of bifunctional nanostructured metal sulfide electrocatalysts, with Co x Mo y S nanosheets supported on carbon cloth (Co x Mo y S-CC). The fabricated Co x Mo y S-CC with an optimized composition and structure exhibited high HER and UOR catalytic performances in alkaline conditions.…”

A Novel Metal–Organic Framework Intermediated Synthesis of Heterogeneous CoS2/CoS Porous Nanosheets for Enhanced Oxygen Evolution Reaction

“…For example, CoS 2 , MoS 2 , and FeS 2 with low cost and convenience of synthesis have been proved to possess considerable electrocatalytic performance. [23,25] Nevertheless, the single compound is often restricted by limited electroactive sites and insufficient stability. To further enhance the electrocatalytic activity, element doping of sulfides and bimetallic sulfides has been extensively reported due to the virtues of rich redox active sites and the synergistic effect.…”

Chemically Activating Tungsten Disulfide via Structural and Electronic Engineering Strategy for Upgrading the Hydrogen Evolution Reaction

“…Two-dimensional transition-metal disulfides, such as tungsten disulfide (WS 2 ) and molybdenum disulfide (MoS 2 ), are promising alternatives toward the HER because of their unique electronic configuration, low cost, and remarkable electrocatalytic stability. , Theoretical and experimental results have demonstrated that their electrocatalytic HER activity is mainly attributed to unsaturated S atoms along the edges, but the high proportion of sulfur atoms in the basal plane is electrochemically inactive, which brings about low atomic utilization efficiency. − Defect engineering through heteroatom doping is widely accepted to trigger new active centers in the electrocatalysts and/or enhance the intrinsic activities of the original active sites, but most of the studies have focused on maximizing edge sites. − Recent investigations have demonstrated that the incorporation of the heteroatoms into MoS 2 can modulate local electronic structure and induce HER activity in the inert basal planes, − but the concomitant transformation of metastable 1T-phase makes it difficult to get insight into the effects of the doped atoms on the catalytic activity of pristine disulfides. ,, Besides, the current exploration for activating basal plane of disulfides mainly focuses on MoS 2 , the improvement of HER activity in WS 2 -based materials is still unsatisfactory, and an overpotential within 100 mV is hard to be achieved at a current density of −10 mA cm –2 . − It is pivotal to develop a new technology to optimize the configuration and electronic structure of WS 2 -based materials for producing high-performance HER electrocatalysts.…”