Titanium dioxide (TiO2) photocatalysis is undoubtedly a vast field for fundamental research and technological development. While many attempts are to be commended for enhancing and improving the efficiency, photonic photocatalysis emerges as an innovative method that introduces structural but not chemical modifications. A critical overview of various currently discussed mechanisms in TiO2 photocatalysis is presented here, pointing out numerous open questions and the effects beneficial or not they may have on TiO2 photonic systems.