Hydrogenated TiO₂ Nanorod Arrays Decorated with Carbon Quantum Dots toward Efficient Photoelectrochemical Water Splitting

Abstract

Limited light harvesting and charge collection are recognized as grand challenges for the exploration of highly efficient TiO₂ photoanodes. To overcome these intrinsic shortcomings, we reported the designed photoanode based on TiO₂ nanoarrays with both hydrogenation treatment and surface decoration of carbon quantum dots (CQDs) toward efficient photoelectrochemical water splitting. The results revealed that hydrogenation treatment could cause the formation of oxygen vacancies to suppress the recombination of photoinduced carriers. Meanwhile, the decorated CQDs could not only play as the electron reservoirs to trap photoinduced electrons but also remarkably enhance the solar light harvesting due to their upconversion effect. The as-fabricated photoanodes exhibited a large photocurrent density of ∼3.0 mA/cm² at 1.23 V versus reversible hydrogen electrode under simulated sunlight, which was the highest one among hydrogenated TiO₂ photoanodes ever reported and was ∼6 times that of pristine analogues.