A Combination of EPR, Microscopy, Electrophoresis and Theory to Elucidate the Chemistry of W- and N-Doped TiO2 Nanoparticle/Water Interfaces

The doping of TiO2-based nanomaterials for semiconductor-sensitised photoreactions has been a practice extensively studied and applied many years. main goal remains the improvement light harvesting capabilities under passive solar irradiation, that in case undoped TiO2 is limited restricted to relatively low latitudes. activity selectivity doped photocatalysts are generally discussed on basis modified band structure; energetics intrinsic or extrinsic gaps including trapping states; redox potentials edges, bending at solid/fluid interfaces; charge carriers scavenging/transfer by/to adsorbed species. Electron (and hole) transfer adsorbates often invoked justify formation highly reactive species (e.g., HO. from water); however, complete description nanoparticle surface chemistry dictating adsorption/desorption events missing overlooked. Here, we show by employing electrochemical triple-layer (TLM) approach nanoparticles/water interface, combination with electron paramagnetic resonance spectroscopy (EPR), transmission microscopy electrophoretic measurements, can elucidate nanoparticles link it nature dopants. Exemplifying cases undoped, as well W- N-doped codoped nanoparticles, how density; surface, Stern ζ potentials; acidity constants; speciation sites influenced dopants their loading.