Highly anisotropic titanium nitride nanowire arrays for low-loss hyperbolic metamaterials fabricated via dynamic oblique deposition

TiN nanopillar-enhanced laser desorption and ionization of various analytes

The present paper reports on the use of TiN nanopillars as a robust analytical substrate for laser desorption/ionization mass spectrometry (LDI-MS). TiN nanopillars were fabricated on silicon wafers through the dynamic oblique deposition of titanium, followed by thermal treatment in an ammonia atmosphere. The TiN nanopillars were readily applicable to a simple "dried-droplet" method in the LDI-MS without surface modification or pre-treatment. A broad range of analytes were investigated, including a small drug molecule, a synthetic polymer, sugars, peptides, and proteins. Intact molecular signals were detected with low noise interference and no fragmentation. The developed TiN-nanopillar-based approach extends the applicable mass limit to 150 kDa (immunoglobulin G) and was able to detect trypsinogen (24 kDa) at levels as low as 50 fmol μL-1 with adequate shot-to-shot signal reproducibility. In addition, we carried out MS analysis on biomolecule-spiked human blood plasma and a mixture of standard samples to investigate the promise of the TiN nanopillars for clinical research. The experimental observations are validated using electromagnetic and heat-transfer simulations. The TiN nanopillars show a reduced reflection and exhibit surges in the TiN surface temperature upon irradiation with electromagnetic radiation. Localization of thermal energy at the tips of the TiN pillars is likely to be responsible for the superior LDI performance. Our results suggest that the development of nanostructured TiN substrates will contribute to the widespread implementation of nanostructured solid substrates for biomedical and clinical applications with simple processes.

Scalable wavelength-selective solar absorber based on refractory TiN nanostructures

Scalable wavelength-selective solar absorbers with both high selectivity and thermostability are desired for efficient utilization of solar thermal energy. In this study, we present a refractory titanium nitride (TiN) moth-eye-like nanostructure, fabricated via oblique deposition, that provides high solar-light absorptivity (0.9) and low emissivity (0.17) at 100 °C under atmospheric conditions. The strong visible-light absorption of the structure is complemented by a Fabry-Pérot resonance that broadens the strong absorption band into the near-infrared light region for certain structure dimensions. In addition, TiN is a promising material, due to its refractory nature, having a very high melting point of 2930 °C. The oblique deposition method used to obtain the nano-structured TiN does not require the use of lithographic techniques or expensive nano-templates, thus it is suitable for large-scale fabrication. The nanostructure and its fabrication method have significant potential for practical applications requiring efficient use of solar-light energy.

Refractory materials and plasmonics based perfect absorbers

In the past decades, metamaterial light absorbers have attracted tremendous attention due to their impressive absorption efficiency and significant potential for multiple kinds of applications. However, the conventional noble metals based metamaterial and nanomaterial absorbers always suffer from the structural damage by the local high temperature resulting from the strong plasmonic photo-thermal effects. To address this challenge, intensive research has been conducted to develop the absorbers which can realize efficient light absorption and simultaneously keep the structural stability under high temperatures. In this review, we present detail discussion on the refractory materials which can provide robust thermal stability and high performance for light absorption. Moreover, promising theoretical designs and experimental demonstrations that possess excellent features are also reviewed, including broadband strong light absorption, high temperature durability, and even the easy-to-fabricate configuration. Some applications challenges and prospects of refractory materials based plasmonic perfect absorbers are also introduced and discussed.