1. TiO2 is an effective photocatalyst for water splitting under UV light through generating electron-hole pairs, but has a large bandgap only absorbing UV light. 2. Nitrogen doping of TiO2 has been explored as a way to narrow the bandgap and enable absorption of visible light, but the exact chemical nature of incorporated nitrogen is unclear from characterization techniques. 3. Preparation methods can result in substitutional or interstitial nitrogen in the TiO2 lattice, but there is no clear correlation between method used and nitrogen state incorporated.