InP/TiO2 heterojunction for photoelectrochemical water splitting under visible-light

Abstract

Hydrogen production through photoelectrochemical (PEC) water splitting on photocatalyst is a green and clean method. In this study, we use density functional theory (DFT) calculations to find that the cage-like InP quantum dots (QDs) sensitized TiO2 is an effective photocatalyst for PEC water splitting under visible-light. A 16-ps first-principle molecular dynamics (FPMD) simulation results indicate that the cage-like InP-12, InP-16, InP-20, InP-24, InP-28, and InP-36 QDs are stable at room temperature (300 K). Furthermore, the calculated energy gaps of InP-16, InP-20, InP-24, InP-28, and InP-36 QDs are about 2.0 eV, which are suitable for visible-light absorption. Stable InP-20/TiO2 heterojunction structure was also obtained by FPMD simulation, and the electronic structure calculation result indicates that the InP-20/TiO2 heterojunction has a favorable type-II band aligment, which could prevent the recombination of photoexcited carriers. Finally, the possible reaction pathways of hydrogen production on InP-20/TiO2 heterojunction were investigated. It is found that energy barrier of hydrogen production of the InP-20/TiO2 is 2.56 eV lower than pure TiO2. Our calculations imply that InP QDs sensitized anatase TiO2 is an effective photocatalyst for visible-light PEC water splitting.