Enabling Effective Electrocatalytic N2 Conversion to NH3 by the TiO2 Nanosheets Array under Ambient Conditions

Rong Zhang; Xiang Ren; Xifeng Shi; Fengyu Xie; Baozhan Zheng; Xiaodong Guo; Xuping Sun

doi:10.1021/acsami.8b06647

Enabling Effective Electrocatalytic N₂ Conversion to NH₃ by the TiO₂ Nanosheets Array under Ambient Conditions

ACS Appl Mater Interfaces. 2018 Aug 29;10(34):28251-28255. doi: 10.1021/acsami.8b06647. Epub 2018 Aug 20.

Authors

Rong Zhang^{1

2}, Xiang Ren¹, Xifeng Shi³, Fengyu Xie⁴, Baozhan Zheng², Xiaodong Guo⁵, Xuping Sun¹

Affiliations

¹ Institute of Fundamental and Frontier Sciences , University of Electronic Science and Technology of China , Chengdu 610054 , Sichuan , China.
² College of Chemistry , Sichuan University , Chengdu 610064 , Sichuan , China.
³ College of Chemistry, Chemical Engineering and Materials Science , Shandong Normal University , Jinan 273165 , Shandong , China.
⁴ College of Chemistry and Materials Science , Sichuan Normal University , Chengdu 610068 , Sichuan , China.
⁵ College of Chemical Engineering , Sichuan University , Chengdu 610065 , Sichuan , China.

PMID: 30117725
DOI: 10.1021/acsami.8b06647

Abstract

NH₃ serves as an attractive hydrogen storage medium and a renewable energy sector for a sustainable future. Electrochemical reduction is a feasible ambient reaction to convert N₂ to NH₃, while it needs efficient electrocatalysts for the N₂ reduction reaction (NRR) to meet the challenge associated with N₂ activation. In this Letter, we report on our recent experimental finding that the TiO₂ nanosheets array on the Ti plate (TiO₂/Ti) is effective for electrochemical N₂ conversion to NH₃ at ambient conditions. When tested in 0.1 M Na₂SO₄, such TiO₂/Ti attains a high NH₃ yield of 9.16 × 10^-11 mol s^-1·cm^-2 with corresponding Faradaic efficiency of 2.50% at -0.7 V vs reversible hydrogen electrode, outperforming most reported aqueous-based NRR electrocatalysts. It also shows excellent selectivity for NH₃ formation with high electrochemical stability. The superior NRR activity is due to the enhanced adsorption and activation of N₂ by oxygen vacancies in situ generated during electrochemical tests.

Keywords: N2 reduction reaction; TiO2 nanosheets; ambient conditions; electrolysis; oxygen vacancies.