Copper Single Atom-Triggered Niobia–Ceria Catalyst for Efficient Low-Temperature Reduction of Nitrogen Oxides

Abstract

To reduce nitrogen oxide (NO x ) emission from diesel engines in the cold-start process benefitting the atmospheric environment, catalysts with superior low-temperature NO x removal efficiency are highly demanded. Herein, we report an efficient Nb 2 O 5 /CuO/CeO 2 (NbCuCe) oxide catalyst for the selective catalytic reduction (SCR) of NO x , showing much higher DeNO x activity below 200 °C, superior sulfur resistance, faster response, and much less NH 3 slip than the stateof-the-art Cu-CHA zeolite catalyst. Atomically dispersed Cu species facilitate the strong interaction between Cu and the Nb/Ce base catalyst, which significantly improves the low-temperature redox properties at Cu−O−Ce sites and NH 3 adsorption/activation at Nb−O−Cu sites, thus contributing to the superior SCR performance of NbCuCe at low temperatures. The developed NbCuCe catalyst is highly promising for efficient DeNO x from cold-start diesel engines and can be coupled with Cu-CHA to achieve a broad operation temperature window.

ZnO with Controllable Oxygen Vacancies for Photocatalytic Nitrogen Oxide Removal

“…Utilizing endless solar light as the driving force, the photocatalytic technique is a practical approach for pollutant treatments, especially for the ones in low concentration but highly toxic, e.g., NO (∼ppb) removal from the atmosphere. − Many successful state-of-the-art photocatalysts have been explored for NO removal since the photocatalytic process can be conducted under ambient conditions without the addition of extra redox reagents, which is specifically applicable for the indoor circumstance . However, the practical applications of the majority of these photocatalysts are still hindered by the major bottlenecks: the limited light absorption from the solar spectrum due to the inappropriate band gap and the dissatisfactory reaction yields caused by the rapid recombination of photogenerated charge carriers.…”

“…Meanwhile, in the most ideal case, the complete removal of NO to nitrate or N 2 is preferred, but the generation of the more toxic byproduct NO 2 via the unselective oxidation by the active oxygen species like •OH is still unavoidable. All aforementioned factors are closely related to the photocatalyst’s microstructures and surface-interface properties, which significantly affect the adsorption and further activation of NO, although the intrinsic structure–function relationship is still ambiguous. − As one of the most discussed surface-interface factors, surface vacant sites on the catalysts display influential roles in extending light absorption, promoting carrier separation, as well as the efficient adsorption/activation of small molecules (e.g., O 2 , H 2 O, and NO). For instance, the selective NO conversion to the nitrate was achieved over oxygen-deficient photocatalysts by facilitating molecular oxygen activation. − Our recent investigation presents that surface vacancy engineering in perovskites provides a promising approach to achieve photocatalytic NO reduction into N 2 by modifying NO-adsorption modes .…”

“…All aforementioned factors are closely related to the photocatalyst’s microstructures and surface-interface properties, which significantly affect the adsorption and further activation of NO, although the intrinsic structure–function relationship is still ambiguous. − As one of the most discussed surface-interface factors, surface vacant sites on the catalysts display influential roles in extending light absorption, promoting carrier separation, as well as the efficient adsorption/activation of small molecules (e.g., O 2 , H 2 O, and NO). For instance, the selective NO conversion to the nitrate was achieved over oxygen-deficient photocatalysts by facilitating molecular oxygen activation. − Our recent investigation presents that surface vacancy engineering in perovskites provides a promising approach to achieve photocatalytic NO reduction into N 2 by modifying NO-adsorption modes . These results strongly validate the significant roles of surface defects for reaction channel controlling during photocatalytic NO removal, which is highly anticipated in the field of environmental pollution control.…”

“…8−10 Many successful state-of-the-art photocatalysts have been explored for NO removal since the photocatalytic process can be conducted under ambient conditions without the addition of extra redox reagents, which is specifically applicable for the indoor circumstance. 10 However, the practical applications of the majority of these photocatalysts are still hindered by the major bottlenecks: the limited light absorption from the solar spectrum due to the inappropriate band gap and the dissatisfactory reaction yields caused by the rapid recombination of photogenerated charge carriers. Meanwhile, in the most ideal case, the complete removal of NO to nitrate or N 2 is preferred, but the generation of the more toxic byproduct NO 2 via the unselective oxidation by the active oxygen species like •OH is still unavoidable.…”

Tailoring the Electronic Structure of Single Ag Atoms in Ag/WO3 for Efficient NO Reduction by CO in the Presence of O2

“…NO x (mainly NO and NO 2 ) in automobile exhausts and factory flue gases is the primary pollutant emitted into the atmosphere. 1 CO, also a pollutant in these waste gases, can be used as a reducing reagent to selectively reduce NO x to N 2 (CO-SCR) with the assistance of a catalyst. This CO-SCR technology offers several advantages, including the simultaneous removal of two harmful gases, CO and NO x , and the avoidance of equipment corrosion caused by the most commonly used NH 3 -SCR technology.…”