The use of photons to directly or indirectly drive chemical reactions has revolutionized the field of nanomaterial synthesis resulting in appearance of new sustainable laser chemistry methods for manufacturing of micro‐ and nanostructures. The incident laser radiation triggers a complex interplay between the chemical and physical processes at the interface between the solid surface and the liquid or gas environment. In such a multi‐parameter system, the precise control over the resulting nanostructures is not possible without deep understanding of both environment‐affected chemical and physical processes. The present review intends to provide detailed systematization of these processes surveying both well‐established and emerging laser technologies for production of advanced nanostructures and nanomaterials. Both gases and liquids are considered as potential reacting environments affecting the fabrication process, while subtractive and additive manufacturing methods are analyzed. Finally, the prospects and emerging applications of such technologies are discussed.
β-NaYF4 microcrystals co-doped with Yb3+, Er3+/Tm3+, and Gd3+ ions were synthesized via a hydrothermal method using rare-earth chlorides as the precursors. The SEM and XRD data show that the doped β-NaYF4 form uniform hexagonal prisms with an approximate size of 600–800 nm. The partial substitution of Y by Gd results in size reduction of microcrystals. Upconversion luminescence spectra of microcrystals upon 980 nm excitation contain characteristic intra-configurational ff bands of Er3+/Tm3+ ions. An addition of Gd3+ ions leads to a significant enhancement of upconversion luminescence intensity with maxima at 5 mol % of dopant.
In this work, the method of selective laser reductive sintering was used to fabricate the sensor-active copper and nickel microstructures on the surface of glass-ceramics suitable for non-enzymatic detection of glucose. The calculated sensitivities for these microsensors are 1110 and 2080 μA mM−1·cm−2 for copper and nickel, respectively. Linear regime of enzymeless glucose sensing is provided between 0.003 and 3 mM for copper and between 0.01 and 3 mM for nickel. Limits of glucose detection for these manufactured micropatterns are equal to 0.91 and 2.1 µM for copper and nickel, respectively. In addition, the fabricated materials demonstrate rather good selectivity, long-term stability and reproducibility.
Two series of β-NaYF4:Ln3+ nanoparticles (Ln = La–Nd, Sm–Lu) containing 20 at. % and 40 at. % of Ln3+ with well-defined morphology and size were synthesized via a facile citric-acid-assisted hydrothermal method using rare-earth chlorides as the precursors. The materials were composed from the particles that have a shape of uniform hexagonal prisms with an approximate size of 80–1100 nm. The mean diameter of NaYF4:Ln3+ crystals non-monotonically depended on the lanthanide atomic number and the minimum size was observed for Gd3+-doped materials. At the same time, the unit cell parameters decreased from La to Lu according to XRD data analysis. The diameter-to-length ratio increased from La to Lu in both studied series. The effect of the doping lanthanide(III) ion nature on particle size and shape was explained in terms of crystal growth dynamics. This study reports the correlation between the nanoparticle morphologies and the type and content of doping lanthanide ions. The obtained results shed light on the understanding of intrinsic factors’ effect on structural features of the nanocrystalline materials.
Ultrashort laser pulses deliver electromagnetic energy to matter causing its localized heating that can be used for both material removal via ablation/evaporation and driving interface chemical reactions. Here, it is shown that both mentioned processes can be simultaneously combined within straightforward laser nanotexturing of Si wafer in a functionalizing solution to produce a practically relevant metal–semiconductor surface nano‐morphology. Such unique hybrid morphology represents deep‐subwavelength Si laser‐induced periodic surface structures (LIPSSs) with an extremely short period down to 70 nm and high‐aspect‐ratio nano‐trenches loaded with controllable amount of plasmonic nanoparticles formed via laser‐induced decomposition of the precursor noble‐metal salts. Moreover, heat localization driving reduction process is utilized to produce surface morphology locally decorated with dissimilar plasmon‐active nanoparticles. Light‐absorbing deep‐subwavelength Si LIPSSs loaded with controllable amount of noble‐metal nanoparticles represent an attractive architecture for plasmon‐related applications such as optical nanosensing where efficient coupling of the propagating optical waves to highly localized electromagnetic “hot spots” is a mandatory requirement. To support this statement, applicability of such hybrid morphology for fluorescence‐based detection of nanomolar concentrations of mercury cations in solution is demonstrated.