Importance of hydrogen migration in catalytic ammonia synthesis over yttrium-doped barium zirconate-supported ruthenium nanoparticles: Visualization of proton trap sites

DOI: 10.1021/acs.jpcc.1c04002

Authors: Christopher Foo (University of Oxford; Diamond Light Source) , Joshua Fellowes (University of Oxford) , Huihuang Fang (University of Oxford) , Alexander Large (Diamond Light Source) , Simson Wu (University of Oxford) , Georg Held (Diamond Light Source) , Elizabeth Raine (University of Oxford) , Ping-Luen Ho (University of Oxford) , Chiu Tang (Diamond Light Source) , Shik Chi Edman Tsang (University of Oxford)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: The Journal Of Physical Chemistry C , VOL 2

State: Published (Approved)
Published: October 2021

Abstract: Barium zirconate perovskites have been systematically investigated as protonic supports for ruthenium nanoparticles in the Haber–Bosch ammonia synthesis reaction. A series of supports based on barium zirconate were synthesized, for which the B-site of the ABO3 perovskite was doped with different aliovalent acceptor cations and in varying ratios, resulting in varying proton conductivities and trapping behaviors. Crucially, we provide direct evidence of the importance of a hydrogen-migration mechanism for ammonia synthesis over these proton-conducting materials from the studies of reaction kinetics, in situ X-ray photoelectron spectroscopy, and neutron powder diffraction (NPD), which requires the proper balance of oxygen vacancy concentration (B-site doping), trapping-site concentration, and proton-hopping activation energy. We report evidence of a large dynamic coverage of OH groups on the support and the first visualization of both weak and strong proton trap sites within the perovskite lattice through the use of NPD.

Journal Keywords: Catalysts; Ruthenium; Hydrogen; Ammonia; Lattices

Subject Areas: Materials, Chemistry


Instruments: B07-C-Versatile Soft X-ray beamline: Ambient Pressure XPS and NEXAFS , I11-High Resolution Powder Diffraction

Added On: 21/10/2021 08:59

Discipline Tags:

Physical Chemistry Catalysis Chemistry Materials Science Nanoscience/Nanotechnology Perovskites Metallurgy

Technical Tags:

Diffraction Spectroscopy X-ray Powder Diffraction X-ray Photoelectron Spectroscopy (XPS) Near Ambient Pressure XPS (NAP-XPS)