Molecular O₂ Activation over Cu(I)-Mediated C≡N Bond for Low-Temperature CO Oxidation

Abstract

The activation of molecular oxygen (O) is extremely crucial in heterogeneous oxidations for various industrial applications. Here, a charge-transfer complex CuTCNQ nanowire (CuTCNQ NW) array grown on the copper foam was first reported to show CO catalytic oxidation activity at a temperature below 200 °C with the activated O as an oxidant. The molecular O was energetically activated over the Cu(I)-mediated C≡N bond with a lower energy of -1.167 eV and preferentially reduced to O through one-electron transfer during the activation process by density functional theory calculations and electron paramagnetic resonance. The theoretical calculations indicated that the CO molecule was oxidized by the activated O on the CuTCNQ NW surface via the Eley-Rideal mechanism, which had been further confirmed by in situ diffuse reflectance infrared Fourier transform spectra. These results indicated that the local C≡N bond electron-state engineering could effectively improve the molecular O activation efficiency, which facilitates the low-temperature CO catalytic oxidation. The findings reported here enhance our understanding on the molecular oxygen activation pathway over metal-organic nanocatalysts and provide a new avenue for rational design of novel low-cost, organic-based heterogeneous catalysts.

Highly Intensified Molecular Oxygen Activation on Bi@Bi2MoO6 via a Metallic Bi-Coordinated Facet-Dependent Effect

“…There is no denying that molecular oxygen activation (MOA), the rate-determining step for photoinduced oxidation reactions on the photocatalyst surface, plays a pivotal role in the light-driven oxidation process especially in ROS generation. − As such, extensive regulation strategies have been applied to modify photocatalysts to promote MOA such as defect engineering, ultrathin structure, and metal deposition . For example, Zhang and his group confirmed that oxygen vacancies (OVs) on BiOCl enable MOA to produce superoxide radicals ( • O 2 – ) in a side-on bridging mode .…”

Catalytic CO Oxidation by Gas-Phase Metal Oxide Clusters

“…The gold–CO interaction that may commonly exist in heterogeneous catalysis can influence the reactivity of the gold catalyst, and the AuCO unit can be dynamically generated under reaction conditions. − However, the mobility of the whole AuCO unit during the catalysis of CO oxidation has not been discovered in previous gas-phase studies. Herein, by studying the reactions of neutral HMOCs in catalytic CO oxidation, we identified that CO adsorption can promote the mobility of the AuCO unit.…”

Directing transition metal-based oxygen-functionalization catalysis

“…17 The activation of molecular O 2 on the surface of heterogeneous catalysts is the key step in different oxidation reactions, such as epoxidation and CO-, hydrocarbon-, alcohol-, and glucoseoxidations. 18 However, oxidation reactions using molecular O 2 oxidant oen have several challenges: (1) the direct oxidation of organic substrates using molecular O 2 typically occurs at harsh conditions (toxic solvents, high temperature, and high pressure); (2) a co-reductant is normally required to complete the oxidation of transition metal-based catalysis; and (3) product selectivity is relatively moderate. 18,19 Likewise, hydrogen peroxide has been studied as it also generates water as its byproduct.…”

“…18 However, oxidation reactions using molecular O 2 oxidant oen have several challenges: (1) the direct oxidation of organic substrates using molecular O 2 typically occurs at harsh conditions (toxic solvents, high temperature, and high pressure); (2) a co-reductant is normally required to complete the oxidation of transition metal-based catalysis; and (3) product selectivity is relatively moderate. 18,19 Likewise, hydrogen peroxide has been studied as it also generates water as its byproduct. Fe-, Mn-, Rh-, W-, and Ti-based catalytic systems are known for employing H 2 O 2 as the terminal oxidant.…”