Nano Anatase TiO₂ Quasi-Core–Shell Homophase Junction Induced by a Ti³⁺ Concentration Difference for Highly Efficient Hydrogen Evolution

Abstract

The fabrication of heterojunctions or homojunctions between semiconductors is a controllable strategy to facilitate charge separation in photocatalysis. The homophase junctions exhibit atomiclevel contact for the fast-speed charge transfer via inducing the built-in electric fields. Herein, a new concept of TiO 2 quasi-core−shell homophase junction induced by a Ti 3+ concentration difference for remarkably enhancing photocatalytic activity is proposed. Nano anatase TiO 2 quasi-core−shell homophase junctions are constructed between the interior with high Ti 3+ concentration (quasi-core) and the surface with no detected Ti 3+ (quasi-shell). Diverse Ti 3+ concentration differences are obtained via regulating the mass ratio of the Ti source. The nano anatase TiO 2 quasi-core−shell homophase junctions exhibit improved photocatalytic hydrogen evolution compared with commercial anatase nanoparticles. To be specific, the maximum hydrogen evolution rate of 50.02 mmol/h/g is 25.4 times superior to that of commercial anatase nanoparticles under solar illumination. Besides, the photocatalytic activity remains stable (H 2 evolution rate of 49.21 mmol/h/g, activity loss of <2%) after five cycles of catalytic test. The promoted photocatalytic activities are ascribed to the constitution of a built-in electrical field between the quasishell and quasi-core induced by the band bending, which accelerates the spatial charge separation and suppresses the recombination of carriers. Moreover, the atomic-level contact at the homophase junction interface provides smooth channels for carrier transfer, resulting in more effective separation and transfer of photogenerated electrons and holes. The synthesis of nano anatase TiO 2 quasicore−shell homophase junctions provides new insights into the efficient separation and transfer of photogenerated carriers for photocatalytic applications.

Enhanced hydrogen evolution reaction performance of anatase–rutile TiO2 heterojunction via charge transfer from rutile to anatase

“…21-1272). 29 Peaks belonging to FTO substrate are also identified in this sample, which might be due to the low film thickness. This could be correlated with the slow decomposition rate of TiCl 4 at low temperature.…”

Black TiO2–x Nanoparticles Decorated with Ni Nanoparticles and Trace Amounts of Pt Nanoparticles for Photocatalytic Hydrogen Generation

“…Further, the hydrogen generation rate achieved using the developed photocatalyst is compared with the previously reported excellent hydrogen generation rate (>10 mmol g –1 h –1 ) over similar TiO 2 -based photocatalysts, mentioning the dissimilar reaction conditions (Table S2). ,,,− …”