Synergetic Effect of Na–Ca for Enhanced Photocatalytic Performance in NOX Degradation by g-C3N4

Abstract

Na–Ca co-doping modified g-C3N4 were prepared through the one pot thermal polymerization under a mixture consisting of melamine and sodium chloride-calcium chloride bi-component metal salt in different proportions. The photocatalytic NOX degradation performance of prepared samples were assessed by NOX toxicity. The results showed that the lowest NOX toxicity of co-doping modified g-C3N4 is 3.49 and 1.77 times than that of Na and Ca single-doping modified g-C3N4 when the weight ratio of melamine to metal salt was 1:0.3. X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscope (SEM), N2 adsorption–desorption were used to characterize the crystalline structures and morphologies of products. Infrared spectrum analyzer (FT-IR), X-ray photoelectron spectroscopy (XPS) were used to study the effects of Na–Ca on the chemical composition of products. And the optical performance of products was characterized by ultraviolet–visible spectra (UV–Vis) and optical luminescence (PL). The results showed that Na–Ca co-doping had a synergic effect on NOX degradation. The larger surface area is equivalent to the increase of photocatalyst dosage. Sodium doping increases NO degradation efficiency by promoting redox capacity and the separation of electron-hole pairs, calcium doping can enhance the chemisorption of NO2 because of the generation of CaCO3 and thus reduce the emission of NO2.