Deep eutectic solvent electrolysis for preparing N and P co-doped titanium dioxide for rapid photodegradation of dyestuff and antibiotic

A deep eutectic solvent electrolysis strategy for preparing N and P co-doped titanium dioxide is proposed and implemented. The solvent is constructed by the co-heating of choline phosphate and urea. Atomic ratios of N and P against TiO2 are lower than 1.37% and 0.67%, respectively. The band-gap of co-doped samples is determined to be 2.67-2.78 eV. A mixed-phase of anatase and rutile photocatalyst shows the highest efficiency for the photodegradation of methylene blue, rhodamine B, and oxytetracycline. The corresponding rate constants are 0.194, 0.112, and 0.085 min-1, respectively. The excellent performance benefits from the expected phase structure, appropriate amount of non-metals co-doping, and the matching bandwidth. Results show that the N, P co-doped TiO2 is significantly competitive with either pure TiO2 or similar doped ones. Findings also demonstrate the feasibility of preparing non-metals co-doped narrow-band-gap TiO2 by using deep eutectic solvent based pure organic solution as the electrolyte.