Taming the Redox Property of A_0.5Co_2.5O₄ (A = Mg, Ca, Sr, Ba) toward High Catalytic Activity for N₂O Decomposition

Abstract

Nitrous oxide (N2O) originating from the combustion of fossil fuels causes serious environmental issues. The design and construction of a catalyst with high performance for the removal of N2O remains challenging. Herein, a series of alkaline-earth metal-modified A0.5Co2.5O4 (A = Mg, Ca, Sr, Ba) catalysts were initiated by a hydrothermal protocol, and their catalytic activities for N2O decomposition were systematically investigated by experimental and density functional theory calculation. The results reveal that the doping of alkaline-earth metals significantly affects the morphology, structure, active oxygen species, oxygen vacancy, and redox property and thereafter the catalytic activity of A0.5Co2.5O4 for N2O catalytic decomposition. The introduction of alkaline-earth metals (A = Ca, Sr, Ba) considerably promoted the reduction of Co3+ to Co2+, thereby improving the electron-donating ability and oxygen vacancy number and thereafter weakening the Co–O bond. As a result, the catalytic activity of N2O decomposition distinctively enhanced. Among them, Ba0.5Co2.5O4 shows optimal N2O decomposition performance by virtue of its outstanding active oxygen species and excellent redox property. However, the doping of Mg suppresses the electron-donating ability of Mg0.5Co2.5O4 and thereafter the catalytic activity for N2O decomposition. Therefore, this work may shine light on the understanding of N2O decomposition over alkaline-earth metal-modified Co-based oxides.

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

“…That is, the Pr site is also involved in the breaking of the N–O bond. From the free energy profile of the N 2 O decomposition pathway, it can be seen that, when Co 3 O 4 catalyzes the N 2 O decomposition, the energy barrier of O 2 molecule desorption course is the highest, that is, O 2 desorption is the rate-determining step, which is also consistent with the previous results. ,, However, with the doping of single atom Pr, the energy barriers of all elementary reactions are reduced, especially in the O 2 desorption process (from *O intermediate to O 2 ).…”

“…This indicates that the ability of Pr course is the highest, that is, O 2 desorption is the ratedetermining step, which is also consistent with the previous results. 21,27,31 In this work, Co 3 O 4 and a series of Pr-doped Co 3 O 4 (Pr/Co molar ratio 0.02−0.15) catalysts were synthesized by a citric acid method (in which a certain amount of urea was added as combustion agent) and applied to the investigation of N 2 O catalytic decomposition. The doping strategy of rare earth elements (such as Y, 31 Ce, 32 Nd, 24 Gd, 15 etc.)…”

“…This indicates that the ability of Pr course is the highest, that is, O 2 desorption is the ratedetermining step, which is also consistent with the previous results. 21,27,31 However, with the doping of single atom Pr, the energy barriers of all elementary reactions are reduced, especially in the O 2 desorption process (from *O intermediate to O 2 ). In this work, Co 3 O 4 and a series of Pr-doped Co 3 O 4 (Pr/Co molar ratio 0.02−0.15) catalysts were synthesized by a citric acid method (in which a certain amount of urea was added as combustion agent) and applied to the investigation of N 2 O catalytic decomposition.…”

“…The introduction of additives into Co 3 O 4 is a very effective strategy to increase its activity. For the past few years, alkali metals potassium, , alkaline earth magnesium, , transition metal cations (Cu, Ni, etc. ), , major group metal elements (such as Pb, Bi), , and light-rare earth oxides , have been used as forceful candidates to improve the N 2 O decomposition activity of Co 3 O 4 catalysts.…”

Enhancement of Cs on Co3O4 for N2O Catalytic Decomposition: N2O Activation and O2 Desorption

“…Relevant studies have shown that the appropriate alkali metal could significantly improve the electron transfer property of catalysts and enhance the catalytic decomposition activity of N 2 O. − By the addition of potassium (K), a basic source, the electronic structure of Mn x Co 1– x Co 2 O 4 spinel structure catalysts’ surface was optimized by Abu-Zied and co-workers, which consequently enhanced the catalytic decomposition performance of N 2 O . Franken et al found that a small amount of K could stabilize the active sites and fine-tune the redox ability of the Cu 0.25 Co 2.75 O 4 catalyst .…”