Hydrazine Hydrate Intercalated 1T-Dominant MoS₂ with Superior Ambient Stability for Highly Efficient Electrocatalytic Applications

Abstract

Metallic 1T-phase MoS2 exhibits superior hydrogen evolution reaction (HER) performance than natural 2H-phase MoS2 owing to its higher electrical conductivity and abundance of active sites. However, the reported 1T-MoS2 catalysts usually suffer from extreme instability, which results in quick phase transformation at ambient conditions. Herein, we present a facile approach to engineer the phase of MoS2 by introducing intercalated hydrazine. Interestingly, the as-synthesized 1T-dominant MoS2 sample demonstrates excellent ambient stability without noticeable degradation for 3 months. Additionally, the 1T-dominant MoS2 exhibits superior electrical conductivity (∼700 times higher than that of 2H-MoS2) and improved electrochemical catalytic performance (current density ∼12 times larger than that of 2H-MoS2 at an overpotential of 300 mV vs the reversible hydrogen electrode, RHE). Through experimental characterizations and density functional theory (DFT) calculation, we conclude that the stabilization of the metallic phase could be attributed to the electron donation from hydrazine molecules to the adjacent Mo atoms. The phase control strategy in this work provides a guideline to develop other highly efficient and stable two-dimensional (2D) electrocatalysts.

Heteroatoms (Si, B, N, and P) doped 2D monolayer MoS2for NH3gas detection

“…The monolayer of MoS 2 , which is purely made of a honeycomb sheet of molybdenum atoms that are covalently sandwiched between two honeycomb sheets of sulfur atoms, is known to have a hexagonal plane of sulfur atoms on either side of a hexagonal plane of Mo atoms. 29,30 After geometric optimization using the ωB97XD/6-311++G(d,p) level of theory, the geometrically optimized lattice parameters for the monolayer surface and its dopant before adsorption were observed to have the following bond lengths. For the boron-doped surface (B@MoS 2 -QD) the B 36 –Mo 13 , B 36 –Mo 4 and B 36 –Mo 15 bond lengths were 2.185 Å, 1.851 Å and 2.185 Å, respectively.…”

Strain Engineering of Two-Dimensional Piezophotocatalytic Materials for Improved Hydrogen Evolution Reaction

“…However, exposures of catalytically active edge Mo ions are limited in this phase, , and the corresponding electrical conductivities are also very low, thus resulting in unsatisfactory HER performances . By contrast, experimental works on 1T MoS 2 have demonstrated outstanding catalytic performances, and several facile chemical routes have been recently proposed to synthesize it . For these reasons, we selected 1T MoS 2 in the present study while considered the typically synthesized 2H polymorph for the rest of monolayers.…”

Anti‐Stoke effect induced enhanced photocatalytic hydrogen production

“…In addition, to replace the expensive Pt cocatalyst, a few other potential candidates, such as Au, 10 Ag, 11 black phosphorus, 12 and MoS 2, 13–24 and so on, have been incorporated with carbon nitride to form heterostructures for photocatalytic hydrogen production. Among them, MoS 2 is considered a promising alternative due to its low cost, abundance, and efficient catalyst for photocatalytic and electrochemical hydrogen evolution both under acidic and basic environments 21,25–27 . However, different from constructing heterostructures with metallic materials, building MoS 2 −carbon nitride heterostructure is quite complicated due to the semiconductor nature of MoS 2 .…”

“…Among them, MoS 2 is considered a promising alternative due to its low cost, abundance, and efficient catalyst for photocatalytic and electrochemical hydrogen evolution both under acidic and basic environments. 21,[25][26][27] However, different from constructing heterostructures with metallic materials, building MoS 2 −carbon nitride heterostructure is quite complicated due to the semiconductor nature of MoS 2 . The heterostructure could behave like a typical type II p−n junction in some cases, and the photo-excited electrons can migrate from the carbon nitride layers to the MoS 2 sheets naturally and facilitate hydrogen production on the active sites of MoS 2 .…”