Doping strain induced bi-Ti3+ pairs for efficient N2 activation and electrocatalytic fixation

Na Cao; Zheng Chen; Ketao Zang; Jie Xu; Jun Zhong; Jun Luo; Xin Xu; Gengfeng Zheng

doi:10.1038/s41467-019-10888-5

Doping strain induced bi-Ti³⁺ pairs for efficient N₂ activation and electrocatalytic fixation

Nat Commun. 2019 Jun 28;10(1):2877. doi: 10.1038/s41467-019-10888-5.

Authors

Na Cao¹, Zheng Chen¹, Ketao Zang², Jie Xu², Jun Zhong³, Jun Luo⁴, Xin Xu⁵, Gengfeng Zheng⁶

Affiliations

¹ Department of Chemistry, Laboratory of Advanced Materials, Shanghai Key Laboratory of Molecular Catalysis and Innovative Materials, Collaborative Innovation Center of Chemistry for Energy Materials, Fudan University, Shanghai, 200438, China.
² Center for Electron Microscopy and Tianjin Key Lab of Advanced Functional Porous Materials, Institute for New Energy Materials, School of Materials, Tianjin University of Technology, Tianjin, 300384, China.
³ Jiangsu Key Laboratory for Carbon-based Functional Materials and Devices, Institute of Functional Nano and Soft Materials (FUNSOM), Soochow University, Suzhou, 215123, China.
⁴ Center for Electron Microscopy and Tianjin Key Lab of Advanced Functional Porous Materials, Institute for New Energy Materials, School of Materials, Tianjin University of Technology, Tianjin, 300384, China. jluo@tjut.edu.cn.
⁵ Department of Chemistry, Laboratory of Advanced Materials, Shanghai Key Laboratory of Molecular Catalysis and Innovative Materials, Collaborative Innovation Center of Chemistry for Energy Materials, Fudan University, Shanghai, 200438, China. xxchem@fudan.edu.cn.
⁶ Department of Chemistry, Laboratory of Advanced Materials, Shanghai Key Laboratory of Molecular Catalysis and Innovative Materials, Collaborative Innovation Center of Chemistry for Energy Materials, Fudan University, Shanghai, 200438, China. gfzheng@fudan.edu.cn.

Abstract

The electrochemical N₂ fixation to produce ammonia is attractive but significantly challenging with low yield and poor selectivity. Herein, we first used density function theory calculations to reveal adjacent bi-Ti³⁺ pairs formed on anatase TiO₂ as the most active electrocatalytic centers for efficient N₂ lying-down chemisorption and activation. Then, by doping of anatase TiO₂ with Zr⁴⁺ that has similar d-electron configuration and oxide structure but relatively larger ionic size, the adjacent bi-Ti³⁺ sites were induced and enriched via a strained effect, which in turn enhanced the formation of oxygen vacancies. The Zr⁴⁺-doped anatase TiO₂ exhibited excellent electrocatalytic N₂ fixation performances, with an ammonia production rate (8.90 µg·h^-1·cm^-2) and a Faradaic efficiency of 17.3% at -0.45 V versus reversible hydrogen electrode under ambient aqueous conditions. Moreover, our work suggests a viewpoint to understand and apply the same-valance dopants in heterogeneous catalysis, which is generally useful but still poorly understood.