Selective catalytic ammonia-to-dinitrogen oxidation (NH 3 -SCO) is highly promising for the abatement of NH 3 emissions from flue gas purification devices. However, there is still a lack of high-performance and cost-effective NH 3 -SCO catalysts for real applications. Here, highly dispersed, electrondeficient Cu-based catalysts were fabricated using nitrogen-doped carbon nanotubes (NCNT) as support. In NH 3 -SCO catalysis, the Cu/NCNT outperformed Cu supported on N-free CNTs (Cu/ OCNT) and on other types of supports (i.e., activated carbon, Al 2 O 3 , and zeolite) in terms of activity, selectivity to the desired product N 2 , and H 2 O resistance. Besides, Cu/NCNT demonstrated a better structural stability against oxidation and a higher NH 3 storage capacity (in the presence of H 2 O vapor) than Cu/OCNT. Quasi in situ X-ray photoelectron spectroscopy revealed that the surface N species facilitated electron transfer from Cu to the NCNT support, resulting in electron-deficient Cu catalysts with superior redox properties, which are essential for NH 3 -SCO catalysis. By temperature-programmed surface reaction studies and systematic kinetic measurements, we unveiled that the NH 3 -SCO reaction over Cu/NCNT proceeded via the internal selective catalytic reaction (i-SCR) route; i.e., NH 3 was oxidized first to NO, which then reacted with NH 3 and O 2 to form N 2 and H 2 O. This study paves a new route for the design of highly active, H 2 O-tolerant, and low-cost Cu catalysts for the abatement of slip NH 3 from stationary emissions via selective oxidation to N 2 .

This study investigates the adsorption and oxidation of isoprene, the most abundant biogenic volatile organic compound, on two common Mn(IV) (hydr)oxides in Earth's surface environment, birnessite and cryptomelane. Both minerals show high adsorption capability toward isoprene under increasing environmental temperature and low relative humidity, whereas the adsorbed isoprene on birnessite is oxidized into carboxylate species, mainly formate. For both Mn(IV) (hydr)oxides, the adsorption of isoprene not only reduces Mn 4+ to Mn 3+ but also gives rise to the slight distortion of the crystal structure. Compared to cryptomelane, birnessite exhibits better adsorption and oxidation capability of isoprene, which is improved by the decrease in crystallinity. This is attributed to the high density of oxygen anions on the (001) surface, owing to the participation of lattice oxygen, electrophilic adsorbed oxygen, and hydroxyl groups in the oxidation of isoprene. For cryptomelane, the particles with short and thick nanorods show higher adsorption capacity but lower oxidizability than those with long and sharp nanorods, as the (001) surface of cryptomelane prefers to adsorb isoprene and Mn 4+ in long sharp nanorods and accept more electrons from isoprene. Based on the experimental results, we propose that Mn(IV) (hydr)oxide in soil dust aerosols is an important regulator of atmospheric isoprene, which enhances the bioavailability of both isoprene and Mn(IV) (hydr)oxides.