Strong Electronic Orbit Coupling between Cobalt and Single-Atom Praseodymium for Boosted Nitrous Oxide Decomposition on Co₃O₄ Catalyst

Abstract

Nitrous oxide (N2O) has gained increasing attention as an important noncarbon dioxide greenhouse gas, and catalytic decomposition is an effective method of reducing its emissions. Here, Co3O4 was synthesized by the sol–gel method and single-atom Pr was confined in its matrix to improve the N2O decomposition performance. It was observed that the reaction rate varied in a volcano-like pattern with the amount of doped Pr. A N2O decomposition reaction rate 5–7.5 times greater than that of pure Co3O4 is achieved on the catalyst with a Pr/Co molar ratio of 0.06:1, and further Pr doping reduced the activity due to PrO x cluster formation. Combined with X-ray photoelectron spectroscopy, X-ray absorption fine structure, density functional theory and in situ near-ambient pressure X-ray photoelectron spectroscopy, it was demonstrated that the single-atom doped Pr in Co3O4 generates the “Pr 4f–O 2p–Co 3d” network, which redistributes the electrons in Co3O4 lattice and increases the t2g electrons at the tetracoordinated Co2+ sites. This coupling between the Pr 4f orbit and Co2+ 3d orbit triggers the formation of a 4f–3d electronic ladder, which accelerates the electron transfer from Co2+ to the 3π* antibonding orbital of N2O, thus contributing to the N–O bond cleavage. Moreover, the energy barrier for each elementary reaction in the decomposition process of N2O is reduced, especially for O2 desorption. Our work provides a theoretical grounding and reference for designing atomically modified catalysts for N2O decomposition.

Boosting N2O Decomposition by Fabricating the Cs–O–Co Structure over Co3O4 with Single-Layer Atoms of Cs

“…The Ea values in the absence of O 2 were observed as 0.69 eV, which was close to the values of 0.53 eV observed over Pr 0.06 Co catalysts. 13 Besides, the energy barrier for the combination of adjacent O* was 0.26 eV, consistent with the results over Co 3 O 4 in the literature as well. 52 On the contrary, in the presence of O 2 (brown line), adsorption and activation of O 2 molecules first occurred, followed by adsorption and decomposition of N 2 O.…”

“…As shown in Figure 3b, the five peaks of pure Co 3 O 4 at 186, 466, 507, 603, and 665 cm −1 presented F 2g , E g , F 2g , F 2g , and A 1g vibration modes, respectively. 13 Furthermore, several additional peaks appeared with Cs of the modified catalysts, indicating the existence of new crystal phases. The unshift peaks of all Cs-modified catalysts at 108 cm −1 were attributed to the A 1g vibration mode of Cs 2 O.…”

“…Shortly, the Euro 7 standard would take effect and probably set the N 2 O emission standard to 0.1 g/kw·h for gasoline and heavy diesel vehicles . At present, it is challenging to eliminate N 2 O emissions from industry and mobile sources, where catalytic decomposition is recognized as one of the most efficient techniques. − …”

High Flux and Stability of Cationic Intercalation in Transition-Metal Oxides: Unleashing the Potential of Mn t2g Orbital via Enhanced π-Donation

“…Within this bandwidth, region I (0−3 eV) corresponds to the Mn 3d states, region II (3−7 eV) to the O 2p nonbonding states, and region III (>7 eV) is identified with the hybridization states of Mn 3d−O 2p. 27 When Ni is doped into the MnO 2 configuration, a significant change is observed: both the O 2p and Mn 3d electron densities decrease while the hybridized electron density of Mn 3d−O 2p increases. This shift implies an amplified orbital hybridization between O 2p and Mn 3d.…”

Beyond Purification: Highly Efficient and Selective Conversion of NO into Ammonia by Coupling Continuous Absorption and Photoreduction under Ambient Conditions

“…Nitrogen oxides (NO x ) primarily emitted from fossil fuel combustion and biomass burning are considered as the major atmospheric contaminants, contributing remarkably to environmental pollution and human health damage. − Currently, selective catalytic reduction (SCR) technology has been utilized as the foremost technology for NO x abatement. By using ammonia as the reducing agent, the SCR process is effective for NO removal in typical stationary emission units such as coal-burning power stations and factories (typical concentration of emitted NO: 500–1000 ppm). − Although the state-of-the-art strategy of SCR has been testified to be feasible and practical, which achieves a superior NO removal ratio of more than 90%, the high energy consumption leads to the excess emission of carbon dioxide due to the high working temperature (>150 °C) during the SCR process. , Moreover, the consumption of massive ammonia causes extra costs and reduces the economic value of the SCR technology.…”