Ceramic nanoparticles that exhibit a plasmonic response are promising next‐generation photonic materials. In this contribution, a solid‐state metathesis method has been reported for the synthesis of Group 4 nitride (TiN, ZrN, and HfN) nanocrystals. A high‐temperature (1000 °C) reaction between Group 4 metal oxide (TiO2, ZrO2, and HfO2) nanoparticles and magnesium nitride powder yielded nitride nanocrystals that were dispersible in water. A localized surface plasmonic resonance was observed in the near‐infrared region for TiN and in the visible region of light for ZrN and HfN nanocrystals. The frequency of the plasmon resonance was dependent on the refractive index of the solvent and the nanocrystal size.

Water desalination via thermal evaporation using plasmonic nanostructures which harness and convert solar irradiation to provide the requisite heat input is gaining interest as a scalable and sustainable method to address global freshwater scarcity. To meet growing freshwater demand in such a manner, new, inexpensive plasmonic nanomaterials that exhibit high solar-tovapor-conversion efficiencies are being sought. Here, plasmonic metal nitride interfaces consisting of TiN, ZrN, and HfN nanoparticles (NPs) with sizes ranging between 10 and 20 nm drop-cast onto nanoporous anodic aluminum oxide (AAO) membranes were analyzed for water evaporation and desalination. Evaporation rates of 1.10 ± 0.05, 1.27 ± 0.04, and 1.36 ± 0.03 kg m −2 h −1 and solar-to-vapor efficiencies of 78, 88, and 95% were observed for TiN, ZrN, and HfN, respectively, under 1 sun illumination. Computational analysis of the solar absorption cross-section of the nitride NPs was consistent with this trend. The HfN−AAO interface was further explored for desalination purposes using Atlantic Ocean saltwater as a source and showed evaporation rates of 1.2 ± 0.2 and 6.1 ± 0.4 kg m −2 h −1 and solar-to-vapor efficiencies of 87 and 99% under 1 and 4 suns, respectively. Inductively coupled plasma mass spectrometry (ICP-MS) measurements showed effective removal of the major metal ions (Na + , K + , Mg 2+ , and Ca 2+ ) following the desalination process using the HfN−AAO interface.

Rapid detection of disease biomarkers at the patient point-of-care is essential to timely and effective treatment. The research described herein focuses on the development of an electrochemical surface-enhanced Raman spectroscopy (EC-SERS) DNA aptasensor capable of direct detection of tuberculosis (TB) DNA. Specifically, a plausible DNA biomarker present in TB patient urine was chosen as the model target for detection. Cost-effective screen printed electrodes (SPEs) modified with silver nanoparticles (AgNP) were used as the aptasensor platform, onto which the aptamer specific for the target DNA was immobilized. Direct detection of the target DNA was demonstrated through the appearance of SERS peaks characteristic for adenine, present only in the target strand. Modulation of the applied potential allowed for a sizeable increase in the observed SERS response and the use of thiol back-filling prevented non-specific adsorption of non-target DNA. To our knowledge, this work represents the first EC-SERS study of an aptasensor for the direct, label-free detection of DNA hybridization. Such a technology paves the way for rapid detection of disease biomarkers at the patient point-of-care.

The search for new plasmonic materials that are low-cost, chemically and thermally stable, and exhibit low optical losses has garnered significant attentiona mong researchers. Recently,m etal nitrides have emerged as promising alternatives to conventional, noble-metal-based plasmonic materials, such as silver and gold. Many of the initial studies on metal nitridesh ave focused on computational prediction of the plasmonic properties of these materials. In recent years, several synthetic methods have been developed to enableempirical analysis. This review highlightssynthetic techniques for the preparation of plasmonic metal nitride nanoparticles, which are predominantly free-standing, by using solid-state and solid-gas phase reactions, nonthermal and arc plasma methods, and laser ablation. The physical properties of the nanoparticles, such as shape, size, crystallinity, and optical response, obtained with such synthetic methods are also summarized.

The photothermal transduction efficiencies of group 4 metal nitrides, TiN, ZrN, and HfN, at λ = 850 nm are reported, and the performance of these materials is compared to an Au nanorod benchmark. Transition metal nitride nanocrystals with an average diameter of ∼15 nm were prepared using a solid-state metathesis reaction. HfN exhibited the highest photothermal transduction efficiency of 65%, followed by ZrN (58%) and TiN (49%), which were all higher than those of the commercially purchased Au nanorods (43%). Computational studies performed using a finite element method showed HfN and Au to have the lowest and highest scattering cross section, respectively, which could be a contributing factor to the efficiency trends observed. Furthermore, the changes in temperature as a function of illumination intensity and solution concentration, as well as the cycling stability of the metal nitride solutions, were studied in detail.