Endogenous Nanoparticles Strain Perovskite Host Lattice Providing Oxygen Capacity and Driving Oxygen Exchange and CH₄ Conversion to Syngas

Abstract

Particles dispersed on the surface of oxide supports have enabled a wealth of applications in electro-photo-and heterogeneous catalysis. Dispersing nanoparticles within the bulk of oxides is, however, synthetically much more challenging and therefore less explored, but could open new dimensions to control material properties analogous to substitutional doping of ions in crystal lattices.Here we demonstrate such a concept allowing extensive, controlled growth of metallic nanoparticles, at nanoscale proximity, within a perovskite oxide lattice as well as on its surface. By employing operando techniques, we show that in the emergent nanostructure, the endogenous nanoparticles and the perovskite lattice become reciprocally strained and seamlessly connected, enabling enhanced oxygen exchange. Additionally, even deeply embedded nanoparticles can reversibly exchange oxygen with a methane stream, driving its redox conversion to syngas with remarkable selectivity and long term cyclability while surface particles are present. These results not only exemplify the means to create extensive, self-strained nanoarchitectures with enhanced oxygen transport and storage capabilities, but also demonstrate that deeply submerged, redoxactive nanoparticles could be entirely accessible to reaction environments, driving redox transformations and thus offering intriguing new alternatives to design materials underpinning several energy conversion technologies.

Surface Segregation in Solid Oxide Cell Oxygen Electrodes: Phenomena, Mitigation Strategies and Electrochemical Properties

“…In addition, Jalili et al [108] grew a 10-nm-thick LSM film onto (001) STO and (001) LAO substrates using PLD to generate in-plane tensile strain and in-plane compression strain, respectively, and observed a higher tendency for SrO segregation and higher concentrations of surface oxygen vacancies on the tensile strained LSM surface due to the larger spacing available for Sr cation accommodation and the reduced elastic energy on the surface as compared with the bulk. This positive effect of tensile strain on increasing oxygen diffusivity has also been reported on Au dispersed Pr 1.9 Ni 0.71 Cu 0.41 Ga 0.05 O 4+δ [109] and La 0.8 Ce 0.1 Ni 0.4 Ti 0.6 O 3 with embedded metal nanoparticles [110], demonstrating that high concentrations of surface oxygen vacancies can play a key role in accelerating SrO segregation.…”

“…The results showed that compressive or tensile interfacial strain can modify the relative concentrations of La and Sr in the interfacial region to achieve better lattice matching. Estrade et al [106,107] also deposited a 20-nm-thick LCM film onto STO (001) and (110) substrates to generate relaxed and tensile strained surfaces, respectively, and their electron energy loss spectroscopy (EELS) results showed that tensile strain can lead to La depletion at the free film surface and La enrichment at the LCM/STO interface, whereas relaxed films were chemically homogeneous. In addition, Jalili et al [108] grew a 10-nm-thick LSM film onto (001) STO and (001) LAO substrates using PLD to generate in-plane tensile strain and in-plane compression strain, respectively, and observed a higher tendency for SrO segregation and higher concentrations of surface oxygen vacancies on the tensile strained LSM surface due to the larger spacing available for Sr cation accommodation and the reduced elastic energy on the surface as compared with the bulk.…”

Elucidation of the reaction mechanism on dry reforming of methane in an electric field by in situ DRIFTs

“…75–77 Lattice oxygen in the catalyst support dissociates CH 4 in the DRM reaction, leading to the formation of oxygen vacancies. 75,78,79…”

“…[75][76][77] Lattice oxygen in the catalyst support dissociates CH 4 in the DRM reaction, leading to the formation of oxygen vacancies. 75,78,79 Consequently, the reaction of CH 4 with lattice oxygen is expected to be an important factor supporting oxygen vacancy formation. Therefore, to investigate the effects of CH 4 on the formation of lattice oxygen defects with or without EF, we took XPS measurements and evaluated the reducibility of CeO 2 .…”

Nanoparticle Ex-solution for Supported Catalysts: Materials Design, Mechanism and Future Perspectives

“…135 Furthermore, the thermally induced ex-solution may find merits where the extreme temperature gradient is routine such as in chemical looping combustion or solar thermal applications. [136][137][138] Heterogeneous Doping Reprinted from Kwak et al, 3 with permission, Copyright 2018, Springer Nature.…”