Boosting nitrogen electrocatalytic fixation by three-dimensional TiO2−δNδ nanowire arrays

• Published in: Journal of energy chemistry Vol. 75; pp. 293 - 300
• Main Authors: Mu, Jianjia, Gao, Xuan-Wen, Liu, Zhaomeng, Luo, Wen-Bin, Sun, Zhenhua, Gu, Qinfen, Li, Feng
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.12.2022
• Subjects: DFT; Electrocatalysis; Nanowires; NRR; TiO2−δNδ; Electrocatalysis; DFT; Nanowires; TiO2−δNδ; NRR
• ISSN: 2095-4956
• DOI: 10.1016/j.jechem.2022.08.007

The catalysts based on TiO2−δNδ nanowires grown on carbon cloth feature a higher yield rate for ammonia than the electrocatalyst without N doping. [Display omitted] Owing to the environmental and inherent advantages, nitrogen reduction reaction (NRR) by electrocatalysts attracts global attention. The surface engineering is widely employed to enhance the electrocatalytic activity by atomic defects and heterostructure effects. A three-dimensional (3D) free-standing integrated electrode was fabricated by numerous nearly-single-crystal TiO2−δNδ nanowire arrays. Based on the high electronic conductivity network, it exposes numerous active sites as well to facilitate the selective nitrogen adsorption and *H adsorption suppression. The synergistic effects between Ti3+ and oxygen vacancy (Ov) boost the intrinsic catalytic activity, in which Ti3+ acquired electrons via Ov can effectively activate the NN bond and make it easy to bind with protons. The energy barrier of primary protonation process (*N2+H++e−→*NNH) can be dramatically decreased. The highest ammonia yield rate (14.33 µg h−1 mgcat−1) emerges at −0.2 V, while the optimal ammonia Faradaic efficiency (9.17%) is acquired at −0.1 V. Density functional theory (DFT) calculation reveals that the Ti3+ can be served as the active sites for nitrogen adsorption and activation, while ammonia synthesis is accomplished by the distal pathway. The high electronic conductivity integrated network and synergistic effects can significantly facilitate nitrogen absorption and accelerate electrocatalytic reaction kinetic, which are responsible for the excellent NRR performance at room temperature.