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Co-existing air pollutants, especially NO x and VOCs, will generate secondary photochemical pollution under light irradiation. However, simultaneous elimination of multi-pollutants has long been a challenge. Photocatalysis could turn the reaction pathway between pollutants to convert them into harmless products, which is a promising technology for multi-pollutant control. Here we achieved synergistic photocatalytic degradation of NO and C 7 H 8 on InOOH photocatalyst, and the performance can be adjusted by H 2 O through affecting the interaction between surface species and catalyst. In situ DRIFTS and GC-MS revealed that the improved efficiency originated from the fast conversion of C–N coupling intermediates led by additional H 2 O. Surface characterizations and DFT simulation determined that accumulated nitrates will compete with the adsorption of NO and C 7 H 8 , resulting in a decline in efficiency in the later stage. Although improved efficiency would bring more nitrates, as H 2 O has comparable adsorption to nitrate at the same site, high humidity can mitigate the deactivation. The photocatalyst can be also simply regenerated by water washing. This work reveals the complex interaction in the multi-pollutant system and provides guidelines for precisely regulating the synergistic removal of NO x and VOCs. [Display omitted] • Synergistic removal of NO x and C 7 H 8 are achieved on InOOH. • H 2 O has a promotion effect on the simultaneous degradation of NO and C 7 H 8. • The enhanced removal originated from the fast conversion of C–N species. • The nitrate would compete with NO and C 7 H 8 adsorption and is the deactivation factor. • H 2 O has comparable adsorption to nitrate at the same site, thus can mitigate the decline in efficiency. [ABSTRACT FROM AUTHOR]

[Display omitted] Developing electrocatalysts for efficient reduction of nitrate contaminant to value-added ammonia as energy carrier is a pivotal part for restoring the nitrogen cycle. However, the selectivity of ammonia is far from satisfaction, often suffering from accumulation of toxic nitrite byproduct. Herein, a series of CuNi alloy nanoparticles embedded in nitrogen-doped carbon matrix (CuNi/NC) with hierarchical pores were fabricated by pyrolysis of bimetallic metal–organic frameworks (MOFs). The catalysts exhibited excellent selectivity (94.4%) and faradaic efficiency (79.6%) for nitrate reduction to ammonia, greatly outperforming the performance of monometallic Cu/NC (selectivity of 60.8% and faradaic efficiency of 60.6%). Impressively, the introduction of nickel distinctly suppressed the production of toxic byproduct of nitrite. Online differential electrochemical mass spectrometry (DEMS) and in situ surface-enhanced infrared absorption spectroscopy (SEIRAS) tests were utilized to reveal the key intermediates and the reaction pathway. Density functional theory (DFT) calculations demonstrated that the introducing of nickel into copper lattice modified both the electronic and geometric structures of the catalysts. The copper and nickel sites in the CuNi alloy catalysts operate synergistically to facilitate the hydrogenation of NO 2 * to HNO 2 * and suppress the hydrogen evolution reaction, boosting the selective formation of ammonia. This work could provide a new synthetic route for bimetallic catalysts and mechanistic understanding for nitrate to ammonia reaction. [ABSTRACT FROM AUTHOR]

[Display omitted] Improving the selectivity of photocatalysis and reducing the generation of toxic by-products are the two key challenges for the development of highly efficient and stable photocatalysts. In this work, it was revealed that Zn-Ti-layered double hydroxide (ZT-LDH) photocatalyst, which generated less intermediates, showed better toluene degradation efficiency (removal ratio, 75.2%) and stability, compared with P25 (removal ratio, 10.9%). During the photocatalytic toluene degradation, benzaldehyde and benzoic acid were the main intermediates existed in the gas phase and on the surface of the catalyst, respectively. By combining experiments with theoretical calculation, it was found that the hydrogen atoms on the hydroxyl groups in the LDH would selectively attract the oxygen atoms in the carbon–oxygen double bond of the two major intermediates, facilitating their adsorption and activation on ZT-LDH. Besides, the surface electronic structure of ZT-LDH was demonstrated to facilitate the ring-opening reaction of the two major intermediates, eventually maintaining high activity and stability. This work could provide new molecular perspectives for understanding the photocatalytic reactions in VOCs degradation and developing efficient and stable photocatalysts. [ABSTRACT FROM AUTHOR]

[Display omitted] • Delocalized electrons were formed on Bi 2 O 2 CO 3 surface by interlayer hydrogenation. • Stable conjugated structure of benzene-ring was tailored, resulting in destabilization. • Direct ring-opening pathway and deep toluene oxidation were achieved. • The reaction pathway of reactants with un-activated benzene-ring was revealed. The stable conjugated structure of benzene-ring poses the persistent challenge for deep oxidation of toluene. In this study, the electronic structure of benzene-ring-containing reactants is tailored by engineering the interlayer hydrogenation in layered Bi 2 O 2 CO 3 , where charge separation and migration capabilities are improved and the confined charge in the interlayer and intralayer could transfer to catalyst surface and serve as delocalized electrons. The ring-opening site, the C = C bond, is activated by delocalized electrons. Consequently, the conjugated structure of the benzene-ring turns into a state with uneven charge distribution, resulting in weakened stability. With the attack of photo-generated radicals, the destabilized benzene-ring structure can be destroyed with direct ring-opening of toluene and achieves deep oxidation of toluene. Therefore, the degradation and mineralization of photocatalytic toluene are improved with great stability and humidity adaptability. This concept of promoting ring-opening with delocalized electrons provides a new strategy for the development of high-performance photocatalyst. [ABSTRACT FROM AUTHOR]