Concurrent Vacancy and Adatom Defects of Mo_1–xNb_xSe₂ Alloy Nanosheets Enhance Electrochemical Performance of Hydrogen Evolution Reaction

Abstract

Earth-abundant transition metal dichalcogenide nanosheets have emerged as an excellent catalyst for electrochemical water splitting to generate H2. Alloying the nanosheets with heteroatoms is a promising strategy to enhance their catalytic performance. Herein, we synthesized hexagonal (2H) phase Mo1–x Nb x Se2 nanosheets over the whole composition range using a solvothermal reaction. Alloying results in a variety of atomic-scale crystal defects such as Se vacancies, metal vacancies, and adatoms. The defect content is maximized when x approaches 0.5. Detailed structure analysis revealed that the NbSe2 bonding structures in the alloy phase are more disordered than the MoSe2 ones. Compared to MoSe2 and NbSe2, Mo0.5Nb0.5Se2 exhibits much higher electrocatalytic performance for hydrogen evolution reaction. First-principles calculation was performed for the formation energy in the models for vacancies and adatoms, supporting that the alloy phase has more defects than either NbSe2 or MoSe2. The calculation predicted that the separated NbSe2 domain at x = 0.5 favors the concurrent formation of Nb/Se vacancies and adatoms in a highly cooperative way. Moreover, the Gibbs free energy along the reaction path suggests that the enhanced HER performance of alloy nanosheets originates from the higher concentration of defects that favor H atom adsorption.

RuO 2 as promoter in Pt‐RuO 2 ‐ nanostructures/carbon composite, a pH ‐universal catalyst for hydrogen evolution/oxidation reactions

“…of RuO 2 ‐Pt/C hybrid are compared with reported noble metal‐based catalysts as given in Table S3. This shows, the RuO 2 ‐Pt/C catalyst is better or comparable to the recently reported catalysts 43‐49 . The HER behavior of RuO 2 ‐Pt/C hybrid was also studied in acid media (Figure 4).…”

“…This shows, the RuO 2 -Pt/C catalyst is better or comparable to the recently reported catalysts. [43][44][45][46][47][48][49] The HER behavior of RuO 2 -Pt/C hybrid was also studied in acid media (Figure 4). S1 suggesting its very high activity.…”

Nontrivial Doping Evolution of Electronic Properties in Ising‐Superconducting Alloys

“…In transition metal dichalcogenides (TMD), the possibility of substituting one of the atomic elements by different species has greatly expanded the potential of this family of 2D materials. This route to obtain novel and stable TMD layers with tailored properties in the form of alloys (M1-δNδX2 or MX2(1δ)Y2δ where M, N are TM and X, Y chalcogens, for binary alloys), has been recently demonstrated, [1,2] and shows significant promise in electronic, [3][4][5][6][7] optoelectronic [2,[8][9][10][11] and catalytic [12][13][14] applications.…”

Ultrathin NiCo Bimetallic Molybdate Nanosheets Coated CuOx Nanotubes: Heterostructure and Bimetallic Synergistic Optimization of the Active Site for Highly Efficient Overall Water Splitting

“…[ 2 ] Efficient electrochemical water splitting by renewable energy is an effective way to produce pure hydrogen energy. [ 3 ] Generally speaking, overall water splitting is carried out through two half cell reactions, including the anode oxygen evolution reaction (OER) and the cathode hydrogen evolution reaction (HER). [ 4 ] However, due to the unsatisfactory thermodynamics and kinetics of both OER and HER, we need to explore a high‐efficiency electrocatalyst to decrease the overpotential and accelerate the reaction speed.…”