Observation of inherited plasmonic properties of TiN in titanium oxynitride (TiOxNy) for solar-drive photocatalytic applications.

This study demonstrates the synthesis of titanium oxynitride (TiOxNy) via a controlled step-annealing of commercial titanium nitride (TiN) powders under normal ambience. The structure of the formed TiOxNy system is confirmed via XRD, Rietveld refinements, XPS, Raman, and HRTEM analysis. A distinct plasmonic band corresponding to TiN is observed in the absorption spectrum of TiOxNy, indicating that the surface plasmonic resonance (SPR) property of TiN is being inherited in the resulting TiOxNy system. The prerequisites such as reduced band gap energy, suitable band edge positions, reduced recombination, and enhanced carrier-lifetime manifested by the TiOxNy system are investigated using Mott-Schottky, XPS, time-resolved and steady-state PL spectroscopy techniques. The obtained TiOxNy photocatalyst is found to degrade around 98% of 10 ppm rhodamine B dye in 120 min and produce H2 at a rate of ∼1546 µmolg-1h-1 under solar light irradiation along with consistent recycle abilities. The results of cyclic voltammetry, linear sweep voltammetry, electrochemical impedance and photocurrent studies suggest that this evolved TiOxNy system could be functioning via plasmonic Ohmic interface rather than the typical plasmonic Schottky interface due to their amalgamated band structures in the oxynitride phase.

Direct Z-scheme mediated SmVO4/UiO-66-NH2 heterojunction nanocomposite for the degradation of antibiotic tetracycline hydrochloride molecules under sunlight.

The use of tetracycline hydrochloride (TCH) for veterinary, human therapy, and agriculture has risen in the past few decades, making it to become one of the most exploited antibiotics. However, TCH residue in the environment is causing issues related to the evolution of antibiotic-resistant bacteria. To address such a problem, photodegradation offers a potential solution to decompose these pollutants in wastewater and thereby mitigates negative environmental impacts. In this context, the research focuses on the use of the rare-earth metal oxide samarium orthovanadate (SmVO4) with nanorod structure, coupled with UiO-66-NH2 for the photocatalytic degradation. Their photocatalytic activity to degrade antibiotic TCH molecules is explored under simulated solar light irradiation. The integration of UiO-66-NH2 with SmVO4 enhanced the light absorption, recombination resistance, carrier lifetime (from 0.382 to 0.411 ns) and specific surface area (from 67.17 to 246 m2/g) of the composite system as confirmed from multiple analyses. The obtained results further indicated that SmVO4/UiO-66-NH2 nanocomposites could form a direct Z-scheme based heterojunction. Such mechanism of charge transfer leads to the effective degradation of TCH molecules up to 50% in 90 min under solar light, while it is degraded only 30% in the case of bare-SmVO4 nanorods. In this work, the incorporation of UiO-66-NH2 positively influences photoelectrochemical properties and improves the overall photoredox properties of SmVO4 for the degradation of complex compounds like antibiotic TCH molecules. Therefore, UiO-66-NH2 can be proposed as an effective material to sensitize the rare-earth based photocatalytic material.