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

This study demonstrates the synthesis of titanium oxynitride (TiON) via a controlled step-annealing of commercial titanium nitride (TiN) powders under normal ambience. The structure of the formed TiON 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 TiON, indicating that the surface plasmonic resonance (SPR) property of TiN is being inherited in the resulting TiON system. The prerequisites such as reduced band gap energy, suitable band edge positions, reduced recombination, and enhanced carrier-lifetime manifested by the TiON system are investigated using Mott-Schottky, XPS, time-resolved and steady-state PL spectroscopy techniques. The obtained TiON photocatalyst is found to degrade around 98% of 10 ppm rhodamine B dye in 120 min and produce H at a rate of ∼1546 μmolgh 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 TiON 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.