The oxidation of gaseous nitric oxide (NO) towards solid nitrate (NO3-) involves several intermediate steps, including reactions that lead to the formation of even more toxic nitrogen dioxide (NO2). In this work, novel graphitic carbon nitride/titanic (g-C3N4/TiO2) composites coupled with calcium carbonate (CaCO3) were synthesized by annealing mixtures of melamine, commercial TiO2 (P25) and calcium acetate (Ca(CH3COO)(2)) at 550 degrees C for 3 h. The structural, morphological and chemical analyses revealed that CaCO3 was formed and homogeneously incorporated in g-C3N4/TiO2 photocatalysts. The composite materials exhibited significantly increased photocatalytic NO oxidation under visible light in comparison to pure g-C3N4 and TiO2 with the presence of CaCO3 to greatly inhibit NO2 release thus improving the overall air quality. The results were related to the influence of both visible light-active g-C3N4 photocatalyst and the basic character of CaCO3 component. (C) 2016 Elsevier B.V. All rights reserved.