Promoting photocatalytic performance of TiO2 nanomaterials by structural and electronic modulation

Abstract

Titanium dioxide (TiO2) possessing excellent visible light response and high separation efficiency of charges without sacrificing its redox ability predicts significant opportunities for an efficient solar energy conversion system. Herein, novel TiO2 nanomaterials with upward-shifted conduction bands and tunable crystal phases were prepared by a lysine doping method. Lysine-doped TiO2 (LDT) showed enhanced reduction potential, efficient charge separation, and improved visible-light absorption. As photocatalysts, LDTs exhibited boosting photocatalytic ability both in light-to-chemical conversion and in refractory pollutant degradation. They can convert visible light to chemical energy and store in nicotinamide adenine dinucleotide (NADH) independent of any electron mediator with a yield of ca. 90%, far beyond that of the undoped TiO2 (13%). As for the refractory pollutant removal, compared to the negligible effect over the undoped TiO2 and commercial titania P25, lysine doping in TiO2 performs as a reaction switch to enable the photodegradation of 4-chlorophenol (4-CP) to proceed. More than 80% of 4-CP was removed with a kinetic constant of 0.8801 h−1. This work presents a distinctive strategy to precisely control the structure of TiO2 nanomaterials and provides a fresh insight into the structural and electronic modulation to promote their photocatalytic performance.