Surface domain heterojunction on rutile TiO2 for highly efficient photocatalytic hydrogen evolution

Abstract

Compared with the highly active anatase TiO₂, rutile TiO₂ usually presents poor photocatalytic performance due to high electron–hole recombination. Herein, we propose a surface domain heterojunction (SDH) structure between adjacent micro-domains with and without chemisorbed chlorine on rutile TiO₂, which utilizes the potential difference between these domains to form a built-in field that promotes charge separation. Single-crystal rutile TiO₂ nanorods assembled into radial microspheres with SDHs were fabricated, and these exhibited excellent solar-driven photocatalytic hydrogen evolution, ∼8-fold higher than that of the pristine one. Experimental results and density functional theory calculations reveal that the exceptional photocatalytic performance can be attributed to the in situ formation of chemisorbed chlorine, which forms SDHs that separate electrons and holes efficiently and results in surface reconfiguration, exposing the tri-active sites, increasing the O-site active centers and enhancing the catalytic activity of the 4-coordinated (Ti_4c) and 5-coordinated Ti sites (Ti_5c). This SDH strategy can extend to other halogen elements and thus provides an universal approach for the rational design of high-efficiency TiO₂ photocatalysts toward sustainable solar-fuel evolution.