DFT Investigation of Substitutional and Interstitial Nitrogen-Doping Effects on a ZnO(100)-TiO2(101) Heterojunction

Ida Ritacco; Olga Sacco; Lucia Caporaso; Matteo Farnesi Camellone

doi:10.1021/acs.jpcc.1c09395

DFT Investigation of Substitutional and Interstitial Nitrogen-Doping Effects on a ZnO(100)-TiO₂(101) Heterojunction

J Phys Chem C Nanomater Interfaces. 2022 Feb 3;126(6):3180-3193. doi: 10.1021/acs.jpcc.1c09395. eCollection 2022 Feb 17.

Authors

Ida Ritacco¹, Olga Sacco¹, Lucia Caporaso¹, Matteo Farnesi Camellone²

Affiliations

¹ Dipartimento di Chimica e Biologia, Università degli Studi di Salerno, via Giovanni Paolo II 132, 84084 Fisciano, Salerno, Italy.
² CNR-IOM, Consiglio Nazionale delle Ricerche - Istituto Officina dei Materiali, c/o SISSA, 34136 Trieste, Italy.

Abstract

Density Functional Theory (DFT) calculations have been performed to investigate the structural and electronic properties of the ZnO(wurtzite)-ATiO₂(anatase) heterojunction in the absence and presence of substitutional, interstitial nitrogen (N) doping and oxygen vacancies (O_V). We report a detailed study of the interactions between the two nonpolar ZnO and TiO₂ surfaces and on the role of N-doping and oxygen vacancies, which are decisive for improving the photocatalytic activity of the heterojunction. Our calculations show that substitutional N-doping is favored in the ATiO₂ portion, whereas the interstitial one is favored in the ZnO region of the interface. Both substitutional and interstitial N-doped sites (i) induce gap states that act as deep electronic traps improving the charge separation and delaying electron-hole recombination, (ii) facilitate the O_V formation causing a decrease in the formation energy (E _FORM), and (iii) do not affect the band alignment when compared to the undoped analogue system. The presented results shed light on the N-doping effect on the electronic structure of the ZnO(100)-TiO₂(101) heterojunction and how N-doping improves its photocatalytic properties.