Laser-synthesized TiN-based nanoparticles as novel efficient electrostatic nanosorbent for environmental water cleaning

Dyes used in industries such as textile, paper, and leather are known to be harmful to both human health and aquatic ecosystems, which makes critically important the search of effective and sustainable methods for their removal from wastewater in order to mitigate the detrimental pollution effects. Here, we show that titanium nitride nanoparticles (TiN NPs) synthesized by scalable methods of pulsed laser ablation in liquid ambient (water, acetone and acetonitrile) can serve as extremely efficient sorbents for water decontamination from dye molecules (methylene blue, crystal violet, and malachite green). Our tests show that adsorption of TiN NPs is associated with the electrostatic effect due to a strong negative charge of laser-synthesized TiN NPs and the presence of pores in the NPs. Comprehensive characterization using scanning and transmission electron microscopy, along with Raman spectroscopy, evidenced that the appearance of surface charge is related to the formation of under-stoichiometric TiN (TiN1-x), associated with the predominance of nitrogen vacancies. This study identifies an optimal configuration of vacancy defects that maximizes dye adsorption, with TiN NPs synthesized in water exhibiting superior performance, achieving a dye sorption capacity of 136.5 mg g-1 at room temperature for methylene blue, which corresponds to best earlier reported values for nanomaterials. This study not only extends the utility of TiN NPs to environmental remediation but also highlights the critical influence of synthesis conditions on their functional properties, offering a pathway towards the design of more effective materials for pollution control.