Oxygen Transfer at Metal-Reducible Oxide Nanocatalyst Interfaces: Contrasting Carbon Growth from Ethane and Ethylene

Abstract

Carbon deposition from hydrocarbon gases onto metal nanoparticles is an important process impacting materials synthesis and catalysis. Typically, light hydrocarbons may decompose on metal nanoparticles resulting in the formation of graphene layers and hydrogen gas. During hydrocarbon reforming, hydrocarbons are converted to syngas (CO and H 2 ), and carbon deposition is an undesirable side reaction, which can deactivate the catalyst and cause mechanical degradation. Here, aberration-corrected in situ environmental transmission electron microscopy (ETEM) was employed to investigate the atomiclevel three-phase interactions occurring at the metal−support interface during the initial stages of carbon deposition from light hydrocarbons over model Ni/CeO 2 and Ni/SiO 2 catalysts. During exposure to C 2 H 6 , no carbon deposition took place, and localized reduction zones at the metal−CeO 2 interface demonstrated a carbon oxidation mechanism. In contrast, during exposure to C 2 H 4 , carbon deposition occurred and was associated with less pronounced reduction zones. The metal−support interface can catalyze the oxidative dehydrogenation of C 2 H 6 and subsequently oxidize the resulting carbonaceous species. For C 2 H 4 , rapid dehydrogenation occurs directly on the Ni surface, which also catalyzes graphite formation. These experiments demonstrate that the ability of interfacial oxygen to inhibit carbon deposition during reforming is strongly influenced by thermodynamic and kinetic considerations, which may show significant variation among different hydrocarbon species.

Threshold catalytic onset of carbon formation on CeO2during CO2electrolysis: mechanism and inhibition

“…With this oxygen storage capability, CeO 2 -based catalysts are also known to be carbon-tolerant as they can oxidize the deposited carbon with lattice oxygen. 27 LT-SOC fuel electrodes combining ceria-based materials with Ni have yielded high performance but their stability in carbon-containing fuels remains a big challenge. 5,28 While carbon deposition has been extensively studied on the Ni surfaces, few studies focus on carbon deposition on CeO 2 .…”

In Situ Analytical Techniques for the Investigation of Material Stability and Interface Dynamics in Electrocatalytic and Photoelectrochemical Applications

“…[144] Subsequent in situ TEM studies have investigated the preparation, activation, and deactivation of various catalyst materials. [145][146][147][148][149][150][151][152] Furthermore, in situ TEM has been implemented to investigate materials involved in electrochemical processes, which is essential for understanding the operando structure-modified mechanisms of electrocatalysts. [153][154][155][156][157][158] For instance, Zhu et al used EC-TEM to gain deeper insight into the degradation mechanisms of Pt-Fe nanocatalysts.…”

The role of surface spin polarization on ceria-supported Pt nanoparticles

“…The dynamic lattice reconfiguration of nanoparticles upon exposing to oxidizing and reducing gases (e.g. CO and O 2 ) has been intensively studied by Transmission Electron Microscopy (TEM) in the recent years [34][35][36]43,[84][85][86][87][88][89][90][91][92] . These studies imply that the surface and perimeter of nanoparticle strongly interact with CO and O 2 gases.…”