Exsolution on perovskite oxides: morphology and anchorage of nanoparticles

Abstract

In this work, we summarize the current state of research regarding the morphology of exsolved nanoparticles on perovskite oxides.

Systematic in situ Investigation of the Formation of NH3 Cracking Catalysts from Precursor Perovskites ABO3 (A=La,Ca,Sr and B=Fe,Co,Ni) and their Catalytic Performance

“…Reference crystal structures were taken from the Inorganic Crystal Structure Database provided by the FIZ Karlsruhe. The deposition numbers of the following structures are given in the references: LaFeO 3 (1), LaCoO 3 (2), LaFe 0.5 Co 0.5 O 3 (3), LaNiO 3 (4), LaFe 0.5 Ni 0.5 O 3 (5, 6), LaCo 0.5 Ni 0.5 O 3 (7), La 0.8 Sr 0.2 CoO 3 (8), La 0.8 Ca 0.2 CoO 3 (9), Fe 2 O 3 (10), Fe 3 O 4 (11), Co 3 O 4 (12), NiO (13). The structures of intermediate phases and final products of the perovskites' decompositions are La 3 Co 3 O 8 (14), La 2 Co 2 O 5 (15), CoO (16), Co (17), La 4 Ni 3 O 9.97 (18), LaNiO 2.5 (19), La 4 Ni 3 O 10 (20), La 3 Ni 2 O 7 (21), Ni (22), La 2 O 3 -cubic (23), La 2 O 3 -trigonal (24), SrO (25), CaO (26), and Fe 3 N (27).…”

“…Catalysts prepared by exsolution have an exceptionally strong particle‐support interaction, hindering these processes [10] . This is due to their anchorage, meaning the nanoparticles are seated in an indentation on the support material [11] …”

“…[10] This is due to their anchorage, meaning the nanoparticles are seated in an indentation on the support material. [11] The aforementioned first study on employing perovskites as precatalysts for ammonia decomposition by Pinzon et al (2021) used the compositions LaNiO 3 and LaCoO 3 . [8] After synthesis via self-combustion, the perovskites were fully reduced with hydrogen to a metallic phase (Ni 0 or Co 0 ) on a lanthanum oxide (La 2 O 3 ) support before catalytic testing.…”

Comparative Study of Exsolved and Impregnated Ni Nanoparticles Supported on Nanoporous Perovskites for Low-Temperature CO Oxidation

“…4,20−27 In particular, the exsolution of Ni NPs has been extensively investigated for high-temperature catalysis and electrocatalysis. 28,29 These studies have shown that exsolved Ni NPs exhibit specific interactions with their parent oxide compared to NPs externally dispersed onto perovskites using conventional impregnation methods due to their embedded structure within the perovskite support. For instance, exsolved Ni NPs were found to be more resistant to agglomeration 5 and coking during high-temperature methane steam reforming, which are two catalyst deactivation causes.…”

“…On the other hand, an A-site deficient perovskite (A 1– x BO 3 ) can boost the irreversible exsolution of NPs, which become socketed in the oxide support. This exsolution process has been studied using noble metals such as Ru, Rh, Pd, and Pt, as well as transition metals including Fe, Co, Ni, and Cu, in many different conditions. ,− In particular, the exsolution of Ni NPs has been extensively investigated for high-temperature catalysis and electrocatalysis. , These studies have shown that exsolved Ni NPs exhibit specific interactions with their parent oxide compared to NPs externally dispersed onto perovskites using conventional impregnation methods due to their embedded structure within the perovskite support. For instance, exsolved Ni NPs were found to be more resistant to agglomeration and coking during high-temperature methane steam reforming, which are two catalyst deactivation causes.…”