arXiv subjects

Andrei V. Kabashin

Publications and source records attributed to Andrei V. Kabashin.

3 recordsLinked to original sources

arXiv2025

Laser-Synthesized Amorphous PdSe$_{\mathrm{2-x}}$ Nanoparticles: A Defect-Rich Platform for High-Efficiency SERS, Photocatalysis, and Photothermal Conversion

The control of material properties at the atomic scale remains a central challenge in materials science. Transition metal dichalcogenides (TMDCs) offer remarkable electronic and optical properties, but their functionality is largely dictated by their stable crystalline phases. Here we demonstrate a single-step, ligand-free strategy using femtosecond laser ablation in liquid to transform crystalline, stoichiometric palladium diselenide (PdSe$_{\mathrm{2}}$) into highly stable, amorphous, and non-stoichiometric nanoparticles (PdSe$_{\mathrm{2-x}}$, with x$\approx$1). This laser-driven amorphization creates a high density of selenium vacancies and coordinatively unsaturated sites, which unlock a range of emergent functions absent in the crystalline precursor, including plasmon-free surface-enhanced Raman scattering with an enhancement factor exceeding 10$^\mathrm{6}$, a 50-fold increase in photocatalytic activity, and near-infrared photothermal conversion efficiency reaching 83$\%$. Our findings establish laser-induced amorphization as a powerful top-down approach for defect-engineered TMDCs and advances their practical usage in optics, catalysis, and nanomedicine.

cond-mat.mtrl-sci↗

arXiv2025

Highly ordered LIPSS on Au thin film for plasmonic sensing fabricated by double femtosecond pulses

Periodic plasmonic arrays making possible excitations of surface lattice resonances (SLRs) or quasi-resonant features are of great importance for biosensing and other applications. Fabrication of such arrays over a large area is typically very costly and time-consuming when performed using conventional electron beam lithography and other methods, which reduce application prospects. Here, we propose a technique of double femtosecond pulse (~ 170 fs) laser-assisted structuring of thin (~ 32 nm) Au films deposited on a glass substrate and report a single-step fabrication of homogeneous and highly ordered Au-based Laser Induced Periodic Surface Structures (LIPSS) over a large area. Our experimental results unveil the key importance of the interpulse delay as the determining factor rendering possible the homogeneity of laser induced structures and confirm that highly ordered, functional LIPSS occur solely upon double pulse irradiation under a specific interpulse delay range. A theoretical investigation complements experimental results providing remarkable insights on the structure formation mechanism. Ellipsometric measurements show that such LIPSS structures can exhibit highly valuable plasmonic features in light reflection. In particular, we observed ultranarrow resonances associated with diffraction-coupled SLRs, which are of paramount importance for biosensing and other applications. The presented data suggest that femtosecond double pulse structuring of thin metal films can serve as a valuable and low-cost tool for a large-scale fabrication of highly ordered functional elements and structures.

cond-mat.mtrl-sci↗

arXiv2025

Laser-Synthesized Ligand-Free Cu Nanocatalysts in Electrochemical CO2 Reduction to Methane

Electrochemical CO2 reduction (eCO2R) represents a pivotal strategy for mitigating global carbon emissions while simultaneously converting renewable energy into storable chemical fuels. Copper-based catalysts have been extensively explored in this field due to their unique capability to catalyze multi-carbon products. However, the intrinsic complexity of eCO2R pathways on Cu surfaces often leads to mixed product distributions, posing a significant challenge for achieving high selectivity toward a single desired hydrocarbon. Herein, we report a breakthrough in methane selectivity using laser-synthesized, ligand-free Cu nanomaterials. Unlike conventional Cu catalysts that produce diverse products, these ligand-free nanoparticles exhibit unprecedented selectivity for methane (CH4) with a Faradaic efficiency (FE) exceeding 70% at superior overpotentials. The absence of surface ligands, a direct consequence of the ultrafast laser ablation synthesis, ensures abundant exposed active sites with tailored electronic and geometric configurations. We attribute the exceptional methane selectivity to the synergistic effects of active sites-rich surfaces and optimized *CO intermediate binding energetics, which favor the protonation pathway toward CH4 rather than C-C coupling. This work not only resolves the long-standing selectivity dilemma in Cu-catalyzed eCO2R but also establishes laser-synthesized ligand-free nanomaterials as a versatile platform for designing high-performance electrocatalysts.

physics.chem-ph↗