Enabling Effective Electrocatalytic N 2 Conversion to NH 3 by the TiO 2 Nanosheets Array under Ambient Conditions
Rong Zhang, Xiang Zhong Ren, Xifeng Shi, Fengyu Xie, Baozhan Zheng, Xiaodong Guo, Xuping Sun
Abstract
NH 3 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 N 2 to NH 3, while it needs efficient electrocatalysts for the N 2 reduction reaction (NRR) to meet the challenge associated with N 2 activation. In this Letter, we report on our recent experimental finding that the TiO 2 nanosheets array on the Ti plate (TiO 2 /Ti) is effective for electrochemical N 2 conversion to NH 3 at ambient conditions. When tested in 0.1 M Na 2 SO 4, such TiO 2 /Ti attains a high NH 3 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 NH 3 formation with high electrochemical stability. The superior NRR activity is due to the enhanced adsorption and activation of N 2 by oxygen vacancies in situ generated during electrochemical tests.