Electron Irradiation Induces the Conversion from 2H-WSe₂ to 1T-WSe₂ and Promotes the Performance of Electrocatalytic Hydrogen Evolution

Abstract

Hydrogen (H2) is an environment-friendly clean energy. In recent years, novel hydrogen evolution electrocatalysts have attracted extensive attention in the scientific community. In this work, the conversion of 2H phase tungsten selenide (2H-WSe2) into 1T phase tungsten selenide (1T-WSe2) was induced by 1 MeV electron irradiation to improve its electrocatalytic performance. When the irradiation fluence is 5 × 1014 e/cm2, the minimum initial overpotential of WSe2 is 101 mV lower than the initial overpotential of WSe2 without irradiation. This method has the characteristics for a simple process and mass production. At the same time, the atomic structure of WSe2 was characterized and the 1T properties of WSe2 were confirmed. The experimental results show that 1 MeV electron irradiates WSe2 to produce Se vacancies on the base surface to form 1T-WSe2, which is the main reason for improving its performance. This effective and feasible electron irradiation method provides a new strategy for the controllable acquisition of 1T-WSe2 and a new method for other similar materials to introduce the ideal 1T phase.

Defect‐Rich MoSe2 2H/1T Hybrid Nanoparticles Prepared from Femtosecond Laser Ablation in Liquid and Their Enhanced Photothermal Conversion Efficiencies

“…They are semiconductors in the stable 2H phase and their band structures change from an indirect bandgap for bulk materials or multilayer nanosheets to a direct bandgap for monolayer nanosheets, whereas the metastable 1T phase demonstrates metallic electronic properties. The tunable band structures based on different numbers of layers and phases result in tunable electronic and optical properties such that TMDCs are broadly applied in semiconductor devices, [ 2–4 ] catalysts, [ 5–8 ] batteries, [ 9–12 ] solar cells, [ 13–15 ] etc.…”

Defect Engineering of MoS2 Nanosheets by Heavy-Ion Irradiation for Hydrogen Evolution

“…These results indicate that the defects in MoS 2 are mainly S vacancies. Under ion irradiation, MoS 2 generates S vacancies more readily than Mo vacancies, consistent with the literature. ,, Electron paramagnetic resonance (EPR) was also performed on as-prepared MoS 2 and F – -2 × 10 13 . As shown in Figure S8, the characteristic peak of the Mo–S dangling bonds can be clearly detected at ∼3339 G, and the g -factor of this resonance is estimated to be 2.003.…”

“…With an increase in fluence, the concentration of F doping and S vacancies also proportionally increase, leading to optimal HER performance of MoS 2 when the fluence is 2 × 10 13 ions/cm 2 . However, with a further increase in fluence to 5 × 10 13 ions/cm 2 , the HER performance of MoS 2 is suppressed, which is attributed to excessive exposure to irradiation, which severely damages the MoS 2 lattice structure, leading to the generation of a large number of disordered regions and subgrain boundaries . On the one hand, previous studies have reported that MoS 2 NSs with lower crystallinity exhibit more grain boundaries, and S vacancies located in or close to grain boundaries are not very active, leading to worse catalytic performance .…”

“…However, with a further increase in fluence to 5 × 10 13 ions/cm 2 , the HER performance of MoS 2 is suppressed, which is attributed to excessive exposure to irradiation, which severely damages the MoS 2 lattice structure, leading to the generation of a large number of disordered regions and subgrain boundaries. 62 On the one hand, previous studies have reported that MoS 2 NSs with lower crystallinity exhibit more grain boundaries, and S vacancies located in or close to grain boundaries are not very active, leading to worse catalytic performance. 79 On the other hand, when the concentration of S vacancies is too high, the intrinsic activity of each site decreases.…”

Enhanced Hydrogen Evolution Reactivity of T’-Phase Tungsten Dichalcogenides (WS2, WSe2, and WTe2) Materials: A DFT Study

“…Alternatively, T’-phase TMDs with metallic characteristics have considerably high catalytic activity resulting from their high electron conductivity and abundant active sites both at the surface areas and edges [ 46 , 47 , 48 , 49 ]. Thus, phase transition engineering has become an effective pathway to improve catalytic performance [ 27 , 28 , 29 , 50 ]. Theoretical analysis results have displayed that the T’-TMDs are a potential candidate catalyst material for HER, especially for T’-MoSe 2 and T’-WS 2 with a hydrogen adsorption free energy (Δ G H* ) of −0.04 eV and 0.03 eV, respectively [ 51 , 52 ].…”