Spectroelectrochemical determination of the conduction band level of mesoporous titanium dioxide semiconductor in diverse reaction media

The conduction band edge ( E CB ) energy levels of a mesoporous TiO 2 film were investigated in aprotic dimethylformamide (DMF) and aqueous media to explore the influence of various proton additives and electron donors. Spectroelectrolysis (SE) technique was employed to measure the E CB in non‐aqueous solvents, revealing a significantly negative E CB in dry non‐aqueous solvents compared to values obtained in aqueous solvents. In non‐aqueous DMF, the E CB of TiO 2 was found to be highly dependent on the proton‐donating additive due to the establishment of a proton adsorption–desorption equilibrium, reaching –(1.42–1.94) V versus SCE. The introduction of a well‐known electron donor, 1,3‐dimethyl‐2‐phenyl‐1,3‐dihydrobenzimidazole (BIH) led to a slight positive shift in the TiO 2 E CB , indicating that the electron donor contributes to the to the CB energetics of the mesoporous TiO 2 films. Under aqueous conditions and in the presence of various electron donors (TEA, TEOA, ascorbic acid, EDTA•2Na, and sodium ascorbate), the proton‐donating/accepting capacity of the additive significantly influenced the pH of the aqueous solvent, causing changes in the TiO 2 E CB across the electrolyte solution. This study emphasizes the crucial role of proton additives and electron donors in influencing the CB energetics of mesoporous TiO 2 electrodes and aims to determine the extent to which the E CB of TiO 2 can shift as a result of the adsorption and intercalation of protons on its surface. The findings obtained herein contribute to the understanding of the energy efficiency of TiO 2 ‐mediated photocatalytic systems in various solvent environments.