A novel dual-functional K0.33WO3-g-C3N4-rGO nanocomposite fabricated using solvothermal and physical mixing for NIR shielding and self-cleaning application

• Solvothermal and physical mixing synthesized K 0.33 WO 3 -g-C 3 N 4 -rGO possessed NIR shielding and photocatalysis performance. • Physical mixing showed the potential with low-cost synthesis. • Solvothermal route achieved superior NIR shielding and RhB or NOx degradation. • Dissolution-reprecipitation during solvothermal process enabled uniform nucleation and strong interfacial coupling. Potassium-doped tungsten bronze (K x WO 3 ) is one of the near-infrared (NIR) shielding materials that has unique properties, including excellent visible transmittance, high transparency, and near-infrared absorption. To fully dig out the improved NIR shielding and photocatalytic properties, a series of novel K x WO 3 /g-C 3 N 4 /rGO nanocomposites was fabricated using two different methods: physical mixing (Method “(P)”) and solvothermal (Method “(S)”). The g-C 3 N 4 content was varied at 18%, 24%, and 38% namely C1, C2, and C3, respectively, then using a fixed 2% rGO to prepare C1-rGO, C2-rGO, and C3-rGO. The optical properties of the composites could be maintained by adjusting K x WO 3 and film thickness. All the nanocomposite films exhibited visible-light transmittance above 70%, and thermal insulation increased upon combining with g-C 3 N 4 and rGO. The double-sided thin film of C3-rGO (S) also showed better NIR shielding properties at 85.5%, compared with C3-rGO (P) at only 75.0%. Moreover, the increment of g-C 3 N 4 content also enhanced the Rhodamine B (RhB) and Nitrogen oxides (NO x ) photodegradation ability of nanocomposites. The C3-rGO (S) showed the highest photodegradation of RhB (100%) and NO x (50.0%). This latter K x WO 3 /g-C 3 N 4 /rGO nanocomposite prepared by the solvothermal method may efficiently be a good candidate in the field of energy-saving and environmental purification.