Modulating the Active Sites of Oxygen‐Deficient TiO2 by Copper Loading for Enhanced Electrocatalytic Nitrogen Reduction to Ammonia

• Published in: Small (Weinheim an der Bergstrasse, Germany) Vol. 18; no. 25; pp. e2200996 - n/a
• Main Authors: Utomo, Wahyu Prasetyo, Wu, Hao, Ng, Yun Hau
• Format: Journal Article
• Language: English
• Published: Weinheim Wiley Subscription Services, Inc 01.06.2022
• Subjects: Ammonia; Charge distribution; Chemical reduction; Copper; electrocatalysis; Electrocatalysts; Electron density; Electron transfer; Nanoparticles; Nanotechnology; Nitrogen; nitrogen reduction; Oxygen; Performance enhancement; TiO 2; Titanium dioxide
• ISSN: 1613-6810; 1613-6829
• DOI: 10.1002/smll.202200996

The electrocatalytic nitrogen reduction reaction (NRR) provides a sustainable route for NH3 synthesis. However, the process is plagued by the strong NN triple bond and high reaction barrier. Modification of catalyst surface to increase N2 adsorption and activation is crucial. Herein, copper nanoparticles are loaded on the oxygen‐deficient TiO2, which exhibits an enhanced NRR performance with NH3 yield of 13.6 µg mgcat−1 h−1 at −0.5 V versus reversible hydrogen electrode (RHE) and Faradaic efficiency of 17.9% at −0.4 V versus RHE compared to the pristine TiO2. The enhanced performance is ascribed to the higher electrochemically active surface area, promoted electron transfer, and increased electron density originated from the strong metal‐support interaction (SMSI) between Cu nanoparticles and oxygen‐deficient TiO2. The SMSI effect also results in lopsided local charge distribution, which polarizes the adsorbed N2 molecules for better activation. This work provides a facile strategy toward the electrocatalyst design for efficient NRR under ambient conditions. Oxygen‐deficient TiO2 loaded with copper nanoparticles is used as an electrocatalyst for nitrogen reduction to ammonia. Both oxygen vacancies (OVs) and copper nanoparticles serve as the active sites. The OVs also manipulate the electron density of the neighboring copper, resulting in the lopsided local charge distribution, which improves the polarization of adsorbed N2 molecules for better activation.