SYNTHESIS AND CHARACTERIZATION OF CRYSTALLINE CARBON NITRIDE/SILVER PHOSPHATE HETEROJUNCTION FOR PHOTOCATALYTIC POLLUTANT DEGRADATION

• Main Author: Jaya Budiarso, Indra
• Format: Theses
• Language: Indonesia
• Subjects: Teknik (Rekayasa, enjinering dan kegiatan berkaitan)
• Online Access: https://digilib.itb.ac.id/gdl/view/82721
• Institution: Institut Teknologi Bandung

Crystalline carbon nitride has gained a lot of interest in the past decades because it can prevent electron-hole (e-h) pair recombination in carbon nitride photocatalyst. However, the insufficient oxidation potential of carbon nitride photocatalyst limits their application in photocatalytic pollutant degradation. Researchers developed Z-scheme heterojunction of carbon nitride with silver phosphate (Ag3PO4) to tackle this limitation. In this work, Z-scheme heterojunction was constructed using potassium poly(heptazine imide) (KPHI) as the crystalline carbon nitride materials and Ag3PO4 as the oxidation photocatalyst. For urea-derived polymeric carbon nitride (PCN), 450 °C is the suitable processing temperature for synthesizing KPHI. Moreover, crucible size affects the final product in which large crucible favors the formation KPHI over small crucible size. KPHI has smaller bandgaps and more efficient e-h pair separation compared to PCN as shown by diffuse reflectance ultraviolet visible light spectroscopy (DR-UV Vis) and photoluminescence spectroscopy (PL). Interestingly, the addition of Ag+ solution to KPHI broke KPHI’s structure as shown by X-ray diffraction (XRD) and transmission electron microscope (TEM). However, the bandgap and PL emission remains unchanged which implies that the optical properties are not significantly affected. In addition, KPHI/Ag3PO4 formed a stronger electronic contact compared to PCN/Ag3PO4 as shown by DR UV-Vis and PL data. The presence of Ag+ ion at the KPHI’s cation adsorption site attracts the PO43- ion to form Ag3PO4 locally at KPHI’s surface. The photocatalytic dye degradation performance which is evaluated through the rate constant value of KPHI/Ag3PO4 is 1.7 times better compared to PCN/Ag3PO4. This result shows that KPHI is a better reduction photocatalyst than PCN to be coupled with Ag3PO4 to form Z-scheme heterojunction.