Details

Autor(en) / Beteiligte

• He, Chengli
• Chen, Yang
• Hao, Zixiang
• Wang, Linrui
• Wang, Mingyan
• Cui, Xiaoli

Titel

Mechanocatalytic Synthesis of Ammonia by Titanium Dioxide with Bridge-Oxygen Vacancies: Investigating Mechanism from the Experimental and First-Principle Approach

Ist Teil von

• Small (Weinheim an der Bergstrasse, Germany), 2024-02, p.e2309500-e2309500

Ort / Verlag

Germany

Erscheinungsjahr

2024

Link zum Volltext

Quelle

Wiley Online Library

Beschreibungen/Notizen

• Mechanochemical ammonia (NH ) synthesis is an emerging mild approach derived from nitrogen (N ) gas and hydrogen (H) source. The gas-liquid phase mechanochemical process utilizes water (H O), rather than conventional hydrogen (H ) gas, as H sources, thus avoiding carbon dioxide (CO ) emission during H production. However, ammonia yield is relatively low to meet practical demand due to huge energy barriers of N activation and H O dissociation. Here, six transition metal oxides (TMO) such as titanium dioxide (TiO ), iron(III) oxide (Fe O ), copper(II) oxide (CuO), niobium(V) oxide(Nb O ), zinc oxide (ZnO), and copper(I) oxide (Cu O) are investigated as catalysts in mechanochemical N fixation. Among them, TiO shows the best mechanocatalytic effect and the optimum reaction rate constant is 3.6-fold higher than the TMO-free process. The theoretical calculations show that N molecules prefer to side-on chemisorb on the mechano-induced bridge-oxygen vacancies in the (101) crystal plane of TiO catalyst, while H O molecules can dissociate on the same sites more easily to provide free H atoms, enabling an alternative-way hydrogeneration process of activated N molecules to release NH eventually. This work highlights the cost-effective TiO mechanocatalyst for ammonia synthesis under mild conditions and proposes a defect-engineering-induced mechanocatalytic mechanism to promote N activation and H O dissociation.