Plasmonic Au₃Cu Ordered Nanocrystals Induced Phase Transformation in 2D‐MoS₂ for Efficient Hydrogen Evolution

Abstract

The synthesis of ordered gold‐copper (Au3Cu) alloy nanocrystals (≈10 nm) is reported and used in the semiconductor (2H) to metallic (1T) phase transformation of an atomically thin large‐area 2D‐MoS2 grown via CVD technique. The ordered Au3Cu nanocrystals are dispersed over 2D‐MoS2, and the phase transformation is confirmed via Raman spectroscopy followed by X‐ray photoelectron spectroscopy (XPS), while the surface properties of the Au3Cu/2D‐MoS2 is determined by the XPS valence band analysis and ultra‐violet photoemission spectroscopy (UPS). By comparing overpotential and Tafel slopes for Hydrogen Evolution Reaction (HER), a decrease is observed in overpotential by 83.2 mV and Tafel slope by ≈58.25 mV per decade for Au3Cu/MoS2 on light irradiation. This electrocatalytic enhancement of Au3Cu/MoS2 refers to the transformation of semiconducting 2D‐MoS2 to metallic phase under light illumination, thereby altering the surface electronic structures, improving carrier concentrations, lowering the valence band edge, and lowering the free energy of H* adsorption/desorption. Density functional theory (DFT) calculations, along with other surface characterizations, further illustrate that the ordered nanocrystal‐induced phase transformation in 2D‐MoS2 leads to a more durable metallic characteristic, thus, enhancing the surface electrical conductivity, reducing surface potential and Gibbs free energy, and improving the kinetics of photoelectrocatalytic performance of the hybrid structure.

Electrophoretic Microplate Protein Identification Based on Gold Staining of Molybdenum Disulfide Hydrogels

“…In addition, there were only the {111} crystal faces of Au nanoparticles after the hydrogels were stained for 20 min. Nevertheless, in the presence of proteins (Figure d), TEM results only showed the 2D layer plane structures after Au staining of 5 min, and the crystal face spacing of 2.60 and 2.44 Å was identified, corresponding to the {101} and {102} crystal faces of MoS 2 , respectively. , Subsequently, similar to the protein-free sample at 5 min, BSA samples exhibited that Au nanoparticles were slightly formed at the edges of MoS 2 nanosheets after staining for 10 min. The reactions between HAuCl 4 and MoS 2 in the hydrogels were remarkably delayed by proteins.…”

“…As an important member of the two-dimensional (2D) family, layered molybdenum disulfide (MoS 2 ) nanosheets have exhibited a series of unprecedented characteristics for diverse applications, such as transistors and electronic devices, − biosensors, , inorganic nanomedicine, − energy, − and catalysts. − The underlying properties of MoS 2 layers are considered for intriguing chemical reactions. For instance, exfoliated MoS 2 seeds served as heterostructural substrates, resulting in the anisotropic accumulation of Au atoms and the formation of chiral plasmonic nanodendritic structures .…”

Ordered Au3Cu Nanocrystals Induced Phase Transformation in 2D-MoS2 as SERS Substrate for Enhancing Molecular Detection

“…Figure a shows an optical micrograph of Au 3 Cu/MoS 2 dispersed with dopamine onto it, whereas Figure b shows a comparative Raman scattering plot of two different concentrations of dopamine, i.e., 1 and 0.5 mg/mL. No enhancement in Raman signals was observed for the concentration of 1 mg/mL, whereas a rise in the signals was observed for 0.5 mg/mL of dopamine, as designated for the characteristic peak positions of 1386, 1429, and 1629 cm –1 . , This enhancement in both MB and dopamine is a result of the plasmon-assisted phase transformation in 2D-MoS 2 via the Au 3 Cu NCs (in this work) as discussed elsewhere …”

“…All of the diffraction peak positions led to the successful formation of the Au 3 Cu-ordered NCs in accordance with the ICSD collection code 611744 and reference code 98-008-5088. The fundamental reflections of (111), (200), and (220) along with the formation of periodic superlattice planes like (100), (110), (210), (211), and (300) provide strong evidence for the successful formation of ordered Au 3 Cu NCs via the solvothermal process . The peak intensity owing to the fundamental reflections, i.e., (111) and (200), will be stronger, because of the atomic planar density and the scattering factor, than the intensity from the planes formed due to the superlattice creation, which is relatively prevalent in the ordered structure.…”

Recent advances of doping strategy for boosting the electrocatalytic performance of two-dimensional noble metal nanosheets

“…Researchers can easily modulate thermodynamic and kinetic factors to influence the morphologies of noble metal nanocrystals by wet-chemistry synthesis. The structures of noble metal nanocatalysts can be broadly categorized into nanoparticles (NPs) [26][27][28][29][30][31][32][33], nanowires (NWs) [34][35][36][37][38][39][40], nanoribbons (NRs), nanosheets (NSs), nanoplates (NPs) and, nanocages [41], nanoframes [2,[42][43][44], etc.…”