K–Ca Synergetic Modified g-C3N4 for Efficient Photocatalytic NO Removal with Low-NO2-Emission.

In this paper, we discuss the synergy of K–Ca in improving the removal efficiency of NO-NO2 by g-C3N4 in detail. The K–Ca modified g-C3N4 (GKXCY, GKC-Z) with varied K/Ca ratio and different dosage of K/Ca were prepared by a one-step thermal polymerization, and the pure g-C3N4 and K/Ca single modified g-C3N4 (GK-X, GC-Y) were taken as control index. The toxicity of NOX was adopt to evaluate the photocatalytic activity, and XRD, SEM, TEM, FT-IR, XPS, UV–Vis, PL and In-situ DRIFTS were taken to characterize the crystal phase, micromorphology, optical characteristics and NO degradation pathway. The results demonstrate that the by-product CaCO3 produced from calcium salt can improve the chemisorption ratio of g-C3N4 to NO-NO2. K–Ca co-doping can synergistically enhance the oxidation activity of g-C3N4 to NO-NO2. From the results, the sample GK0.1C0.4 was endowed with the best NOx degradation activity through K–Ca co-doping which can dramatically decrease the toxicity of NOX from 1 to 0.706 within 30 min. [ABSTRACT FROM AUTHOR]