Struktur Dan Aktivitas Fotokatalitik Komposit Graphitic Carbon Nitride/N-TIO2 Nanotube (G-c3n4/N-Tnt) Dengan Variasi Rasio Massa G-c3n4 Terhadap Naphthol Blue Black

Abstract

Titanium dioxide (TiO2) is the one of the most widely used semiconductor photocatalyst. However, its application under visible-light irradiation is limited by its wide bandgap. Coupling nitrogen-doped TiO2 nanotubes (N-TNT) with graphitic carbon nitride (g-C3N4) is expected to enhance visible-light absorption and improve photocatalytic performance through heterojunction formation. This study investigated the effect of g-C3N4 mass ratio on structural characteristics and photocatalytic activity of g-C3N4/N-TNT composites toward naphthol blue black (NBB) degradation. The composits were synthesized by the ultrasonication-assisted dispersion method with g-C3N4 mass ratio of 1:9, 3:7, 1:1, and 2:1. The synthesized materials were characterized using X-Ray diffraction (XRD), Fourier Transform Infra-red (FTIR), Raman spectroscopy, Scanning Electron Microscopy–Energy Dispersive X-Ray (SEM–EDX), Surface Area Analyzer (SAA analysis of N2 adsorption isotherms using BET model), and UV–Visible Diffuse Reflectance Spectroscopy (UV–Vis DRS). Photocatalytic activity was evaluated through NBB degradation under visible-light irradiation using a 100 W LED lamp, while the reaction kinetics were analyzed using pseudo-first-order model. Characterization results confirmed the successful formation of g-C3N4/N-TNT composites through physical coupling without formation of new crystalline phases or functional groups. Increasing the g-C3N4 content modified the morphology, elemental composition, specific surface area, and optical properties of composites, while reducing the bandgap from 3,00 eV for N-TNT to 2,67–2,73 eV. The g-C3N4/N-TNT 3:7 composite exhibited the highest specific surface area of 69,889 m2g-1. Photocatalytic evaluation demonstrated that all composites exhibited higher activity than the individual materials. The g-C3N4/N-TNT composite with 1:1 mass ratio showed the highest photocatalytic performance, achieving 65,26% NBB removal after 180 min of visible-light irradiation (based on C1) and the highest apparent rate constant (K_app) of 0,0059 min-1.