Triangle Cl−Ag₁−Cl Sites for Superior Photocatalytic Molecular Oxygen Activation and NO Oxidation of BiOCl

Abstract

BiOCl photocatalysis shows great promise for molecular oxygen activation and NO oxidation, but its selective transformation of NO to immobilized nitrate without toxic NO2 emission is still a great challenge, because of uncontrollable reaction intermediates and pathways. In this study, we demonstrate that the introduction of triangle Cl‐Ag1‐Cl sites on a Cl‐terminated, (001) facet‐exposed BiOCl can selectively promote one‐electron activation of reactant molecular oxygen to intermediate superoxide radicals (•O2‒), and also shift the adsorption configuration of product NO3‒ from the weak monodentate binding mode to a strong bidentate mode to avoid unfavorable photolysis. By simultaneously tuning intermediates and products, the Cl‐Ag1‐Cl‐landen BiOCl achieved > 90% NO conversion to favorable NO3‒ of high selectivity (> 97%) in 10 min under visible light, with the undesired NO2 concentration below 20 ppb. Both the activity and the selectivity of Cl‐Ag1‐Cl sites surpass those of BiOCl surface sites (38% NO conversion, 67% NO3‒ selectivity) or control O‐Ag1‐O sites on a benchmark photocatalyst P25 (67% NO conversion and 87% NO3‒ selectivity). This study develops new single‐atom sites for the performance enhancement of semiconductor photocatalysts, and also provides a facile pathway to manipulate the reactive oxygen species production for efficient pollutant removal.

Photocatalytic NOx removal and recovery: progress, challenges and future perspectives

“…Among the redox products of NO x , NO 3is the dominant and accessible substance on the surface of photocatalyst 39,67 . Significant quantities of NO 3are released into the environment through processes such as the combustion of fossil fuels and agricultural activities, driven by the progress of urbanization and industrialization 115 .…”

“…Particularly noteworthy is the effect of silver atoms loaded onto BiOCl (001) facet-exposed nanosheets, which constructed triangular Cl-Ag 1 -Cl sites on Cl-terminated BiOCl. These sites selectively activated molecular oxygen to •O 2and enhanced nitrate adsorption by altering the coordination mode of nitrate on the catalyst, thereby preventing nitrate decomposition (Figure 1e, f)39 . The NO x removal efficiency of Ag 1 /BiOCl reached up to 90%, with 97% selectivity for NO 3and minimal emission of NO 2 (Figure1g-i).In summary, the introduction of single atoms can significantly enhance the adsorption of O2 and H 2 O molecules and the generation of •O 2and •OH, thereby improving both the performance and nitrate Page 6 of 44 Chemical Science Chemical Science Accepted Manuscript Open Access Article.…”