Deep eutectic solvent-assisted synthesis of oxygen vacancy-rich BaTiO3 as a support for Ru catalyst in ammonia synthesis at atmospheric pressure

Ba-based perovskite oxides rich in oxygen vacancies (OVs) are anticipated to possess robust electron-donating capabilities and other favourable properties, rendering them a promising support for Ru catalysts in NH3 synthesis. Herein, a glucose-urea deep eutectic solvent calcinating method was developed to synthesize an OV-rich BaTiO3 (BTO-H) support for Ru catalysts. The BTO-H-supported Ru (Ru/BTO-H) catalyst achieves an impressive NH3 synthesis rate of 5133 μmol gcat–1 h−1 (256.7 mmol gRu–1 h−1) at 400 °C and 0.1 MPa, surpassing the performance of Ru catalysts supported on OV-poor BTO supports and other supported Ru catalysts. Physical characterizations and kinetic experiments reveal the multifaceted influence of OVs on enhancing the catalytic performance of Ru/BTO-H in NH3 synthesis. OVs serve as electron donors to Ru catalyst, facilitating the activation and dissociation of N2. Simultaneously, OVs act as hydrogen acceptors from the Ru surface, mitigating hydrogen poisoning effects. Additionally, OVs stimulate the formation of surface hydrides, not only providing active sites for N2 activation but also bestowing an electron-donating effect on the supported Ru catalyst. The combined positive effects of OVs establish BTO-H as an outstanding support for Ru catalysts in NH3 synthesis.