High Electrocatalytic Activity of Defected MX₂/Graphene Heterostructures (M = Mo, W; X = S, Se) for Hydrogen Evolution Reaction

Abstract

Two-dimensional transition metal dichalcogenides have been regarded as cheap and abundant catalysts for driving electrolysis of water. Using density functional theory methods, we systematically investigate the hydrogen evolution reduction of metal dichalcogenides/ graphene heterostructures (MX 2 /Gs, M = Mo, W; X = S, Se) with various defects, MX 2 /G_V X , MX 2 /G_V M , and MX 2 /G_V (M+X) . We find that such defected MX 2 /Gs show better hydrogen evolution reactive activities than pure MX 2 /Gs as well as freestanding MX 2 monolayers, due to the metallic states induced by the defects. Particularly, MX 2 / G_V X s with a S(Se) vacancy display catalytic performance comparable to that of Pt. Moreover, the catalytic performance for the hydrogen evolution reaction of most defected MX 2 /G_V M s and MX 2 /G_V (M+X) s varies with H coverage and the M vacancy concentration. Our results provide a feasible way to apply MX 2 /graphene heterostructures to water electrolysis for hydrogen production.

Strain engineering of electrocatalysts for hydrogen evolution reaction

“…Specifically, as an important descriptor of hydrogen evolution reaction, the Gibbs free energy of hydrogen adsorption (DG H* ) follows the Sabatier principle and should be neither too strong nor too weak. 11,12 Too strong would make it difficult for H protons to desorb and form H 2 , and conversely there would be few activated hydrogen ions. Ideally DG H* values should be close to zero.…”

Ultrathin MoS1.68Se0.32 Alloy Nanoflakes: An Intercalation-Type Positive Electrode Material for Rechargeable Aluminum-Ion Battery

“…We have carried out DFT calculations using the generalized gradient approximation with the Perdew–Burke–Ernzerhof exchange–correlation functionals as implemented in the VASP 5.4.4 program. , We have applied Grimme’s DFT-D3 method with Beck–Johnson damping , to include the dispersion correction to the DFT energies. In the simulations, we have employed the plane waves with a cutoff energy of 300 eV and the projector-augmented wave pseudopotentials. , Considering the size of the modeled supercell, we have adopted a 4 × 4 × 1 Monkhorst–Pack k -point grid for the Brillouin zone integrations.…”

Hydrogen Production and Degradation of Ciprofloxacin by Ag@TiO2-MoS2 Photocatalysts

“…Industrial development, together with energy shortages and overpopulation of the planet, is perhaps among the most relevant factors affecting the environment and the future sustainable development of society [1][2][3][4][5][6][7]. Serious environmental pollution problems, which are ultimately responsible for global warming, are becoming increasingly important [3].…”

“…In this regard, chemical compounds that emulate the same mechanism as nature can be a realistic alternative that allows for solving a large part of these problems [9]. Hydrogen production by electrochemical water splitting is considered a simple and sustainable method of obtaining clean hydrogen, as energy carrier, through a hydrogen evolution reaction (HER) [4,5,[10][11][12][13]. Until now, the most effective materials for catalyzing HER have been the metals of the platinum (Pt) group [5,12,14].…”

“…Molybdenum disulfide (MoS 2 ) is considered a promising HER catalyst due to its high catalytic activity, high abundance, and low cost [6,12,18]. There are different experimental procedures that allow for synthesizing MoS 2 in a simple way, although its use is certainly limited by the intrinsic semiconductor behavior and the number of active sites [4,6,19]. To improve this behavior, and in the same way that has been addressed with TiO 2 , different strategies have been developed to modify morphology, specific surface and even the presence of structural defects induced by metal doping (e.g., Pt, Cr, Mn, V) [1,7,11].…”