Converting Ag3PO4/CdS/Fe doped C3N4 based dual Z-scheme photocatalyst into photo- Fenton system for efficient photocatalytic phenol removal

• Fabrication of Ag 3 PO 4 /CdS/Fe doped C 3 N 4 based dual Z-scheme photocatalyst. • Conversion of photocatalyst into photo-Fenton catalyst via H 2 O 2 coupling. • Enhanced production of hydroxyl radicals during degradation process. • The complete mineralization of phenol was attainted. • The proposed system exhibited negligible iron leaching and high recyclability. In this work, a dual Z-scheme Ag 3 PO 4 /CdS/Fe-g-C 3 N 4 (AP/CdS/FeCN) photocatalyst was prepared by precipitation- deposition method. AP/CdS/FeCN photocatalyst was converted into the heterogenous photo-Fenton system with the addition of H 2 O 2 . The synergistic coupling between AP/CdS/FeCN and H 2 O 2 resulted in enhanced for phenol degradation, with a rate constant of constant 6.2 × 10 −4 s -1 , which is 1.31 and 1.61 times than that of AP/CdS/FeCN and Fe 2 O 3 /H 2 O 2 . The enhancement in photodegradation was attributed to (i) more regeneration of Fe 2+ ions, (ii) enhanced visible light absorption, (iii) elevated redox potential due to more hydroxyl radical’s formation, and (iv) low Fe leaching in the reaction solution. As indicated by EIS, PL, and trapping experiments, photoinduced CB electrons of g-C 3 N 4 and CdS were transferred entirely to Fe 3+ to regenerate Fe 2+ ions to accelerate the Fenton cycle. In comparison to the conventional Fe 2 O 3 /H 2 O 2 Fenton process, Fe ion leaching in AP/CdS/FeCN/H 2 O 2 catalytic system was almost negligible. It confirmed strong chemical interaction of Fe 3+ with g-C 3 N 4 . AP/CdS/FeCN/H 2 O 2 displayed significant catalytic efficacy and firmness for five successive catalytic cycles. Moreover, the AP/CdS/FeCN/H 2 O 2 nanocomposite exhibited substantial mineralization perfomance for other phenolic pollutants. The results demonstrate that AP/CdS/FeCN/H 2 O 2 catalytic system has the potential for water purification.