An oxygen vacancy-rich two-dimensional Au/TiO hybrid for synergistically enhanced electrochemical N activation and reduction

• Published in: Journal of materials chemistry. A, Materials for energy and sustainability Materials for energy and sustainability, 2020-04, Vol.8 (14), p.6586-6596
• Main Authors: Zhao, Sen, Liu, Han-Xuan, Qiu, Yu, Liu, Shuang-Quan, Diao, Jin-Xiang, Chang, Chun-Ran, Si, Rui, Guo, Xiao-Hui
• Format: Article
• Language: English
• ISSN: 2050-7488; 2050-7496
• DOI: 10.1039/d0ta00658k

The electrochemical nitrogen reduction reaction (NRR) is emerging as a promising sustainable technique that can convert nitrogen (N 2 ) to ammonia (NH 3 ) under ambient conditions. However, the selectivity and electrocatalytic activity of the NRR obtained experimentally to date are still unsatisfactory. As a consequence, it remains a technical challenge to develop scalable, low-cost, and efficient NRR electrocatalysts. Herein, we present an oxygen vacancy (V O )-rich two-dimensional gold (Au)/titanium dioxide (TiO 2 ) hybrid that acts as an advanced NRR electrocatalyst under ambient conditions. Electrocatalytic testing demonstrated that the Au/TiO 2 hybrid catalyst delivered a promising NH 3 yield of 64.6 μg h −1 mg −1 cat and a high faradaic efficiency of 29.5% at −0.40 V versus the reversible hydrogen electrode in acidic media. Experimental findings and theoretical calculations demonstrate that the strong electron-donating effect of V O in TiO 2 was essential for N 2 activation. Meanwhile, the introduction of Au promotes both the electrochemical and thermodynamic rate-limiting steps by adjusting the electronic structure of the active sites. Together, these effects greatly facilitate the activation and reduction of N 2 under ambient conditions. The specific catalyst design strategy in our work represents an alternative avenue to produce other two-dimensional electrocatalysts with high NRR activity and selectivity through rational structural engineering. An oxygen vacancy-rich Au/TiO 2 hybrid nanosheet is used as an electrocatalyst for NRR that delivers a high NH 3 yield of 64.6 μg h −1 mg −1 cat and an faradic efficiency (FE) of 29.5% and excellent structural stability under ambient conditions.