Janus Flower-Like Hollow TiO₂ Photocatalysts Bearing RuO₂ and Pt Nanoparticles for Solar-Light-Driven Catalytic H₂ Evolution

Abstract

The reaction efficiency of TiO 2 -based photocatalysts can be improved through the effective utilization of light and separation of carriers, which can be achieved via material structure designing. Herein, the synthesis of a novel hollow flowerlike TiO 2 -based nanomaterial by regulating the positions of dual cocatalysts on a Janus surface is reported. The dual cocatalysts (RuO 2 and Pt NPs) with redox capability were selectively deposited on different surfaces (constructed Janus surface) of TiO 2 materials to achieve directional transfer and spatial separation of photogenerated charges. Furthermore, the presence of dual cocatalysts may reduce the activation energy necessary for the reaction, enable the catalytic reaction to progress in a favorable direction, and increase the catalyst capability. Additionally, hollow nanostructures significantly shorten the migration distance of photogenerated carriers, owing to their thin-shell structure, further improving the separation of electron−hole pairs and migration efficiency. The results indicate that the deposition positions of the dual cocatalysts significantly affect the H 2 -evolution rate. Further studies reveal that macromolecule OH − exhibits a lower probability of entering the inner surface of the catalyst to participate in the reaction, whereas micromolecule H + demonstrates a higher probability of entering the inner surface of the catalyst, leading to differences in catalyst activity. Among the analyzed samples, PTR demonstrates the most notable H 2 -evolution rate, reaching 4,024 μmol g −1 h −1 , which is higher than those of pure TiO 2 and RTP by 60.96-and 1.22-fold, respectively. Furthermore, the mechanism of the charge migration pathway was analyzed via ultraviolet photoelectron spectroscopy, Mott−Schottky plots, and ultraviolet− visible diffusive reflectance spectroscopy. Catalyst activity increased substantially under illumination owing to the synergy between the special hollow Janus structure and the spatially separated dual cocatalysts.