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 com-mercial 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 corre-sponding to TiN is observed in the absorption spectrum of TiOxNy, indicating that the surface plasmonic reso-nance (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 H-2 at a rate of similar to 1546 mu molg(-1)h(-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.

Automated summary

This study synthesizes titanium oxynitride (TiOxNy) through controlled step-annealing of commercial titanium nitride (TiN) powders in normal ambience. The resulting TiOxNy system inherits the surface plasmonic resonance (SPR) property of TiN, as confirmed by various analysis techniques. The TiOxNy system exhibits desirable prerequisites for enhanced photocatalytic activity, such as reduced band gap energy and enhanced carrier-lifetime. Under solar light irradiation, the TiOxNy photocatalyst shows efficient degradation of rhodamine B dye and production of H-2. The TiOxNy system functions via a plasmonic Ohmic interface due to its amalgamated band structures.