In situ oxidation of carbon-encapsulated cobalt nanocapsules creates highly active cobalt oxide catalysts for hydrocarbon combustion

Abstract

Combustion catalysts have been extensively explored to reduce the emission of hydrocarbons that are capable of triggering photochemical smog and greenhouse effect. Palladium as the most active material is widely applied in exhaust catalytic converter and combustion units, but its high capital cost stimulates the tremendous research on non-noble metal candidates. Here we fabricate highly defective cobalt oxide nanocrystals via a controllable oxidation of carbon-encapsulated cobalt nanoparticles. Strain gradients induced in the nanoconfined carbon shell result in the formation of a large number of active sites featuring a considerable catalytic activity for the combustion of a variety of hydrocarbons (methane, propane and substituted benzenes). For methane combustion, the catalyst displays a unique activity being comparable or even superior to the palladium ones.

Methane combustion over Pd/CoAl2O4/Al2O3 catalysts prepared by galvanic deposition

“…S1 †). 4,5,7,11,22,24,33,36,43 The apparent activity followed a different trend PdAl-I > PdCoAl-SI at high temperatures. CoAl900 showed no catalytic activity below 400 C, thereby suggesting that Pd species were the active sites in this reaction.…”

Non-noble metal catalysts for hydrogenation: A facile method for preparing Co nanoparticles covered with thin layered carbon

“…S14, metallic Co NPs crack into smaller CoOx NPs after the calcination in air at 250 o C, which has also been observed in other works. 33 The crystal lattice fringes of CoOx NPs can be observed in the HRTEM images, though, there are still some metallic Co NPs in the Co@C-250Air sample. Some carbon layers can still be found on Co-CoOx and CoOx NPs in Co@C-250Air, as was confirmed by Raman spectra.…”

Cobalt oxide nanoparticles can enter inside the cells by crossing plasma membranes

“…Cobalt NPs have a large use in industrial and biomedical applications. They efficiently catalyse the combustion of various hydrocarbons 20 and the degradation of water pollutants 21 providing a cheap candidate to replace noble metals. Cobalt NPs are also used in electrocatalysis for the oxygen evolution reaction 22 , important in hydrogen generation.…”