Band gap narrowing ternary phosphorus-doped g-C3N4/Fe0@expanded graphite carbon layer hybrid composite for effective degradation of tetracycline via multiply synergistic mechanisms

The wide band gap of g-C 3 N 4 and severe aggregation of Fe 0 adequately limit their applications. To address these two critical issues, novel ternary phosphorus-doped g-C 3 N 4 /Fe 0 @expanded graphite carbon layer (P-CN/Fe 0 @EGC) photocatalyst with extremely narrow band gap and significantly enhanced catalytic activity was in-situ synthesized. P-CN/Fe 0 @EGC hybrid composite exhibited excellent photodegradation performance of tetracycline (TC) removal, which is 5.18 and 1.92 times higher than that of pristine g-C 3 N 4 and Fe 0 , respectively. Enhancement in photocatalytic activity is evaluated via photoluminescence (PL), UV–vis DRS, XRD and electron spin resonance (ESR). A reasonable catalytic mechanism of P-CN/Fe 0 @EGC is proposed. The multiply synergistic mechanisms of phosphorus-doped g-C 3 N 4 (P-CN), Fe 0 and expanded graphite carbon layer (EGC), as well as the strong reducibility of Fe 0 were accounted for the expanded visible light absorption range. The even dispersion of Fe 0 on porous and worm-like structured P-CN/EGC effectively and successfully avoided the decline in photocatalytic activity caused by aggregation of Fe 0 nanoparticles . Compared with g-C 3 N 4 , the band gap of phosphorus-doped g-C 3 N 4 was narrowed from 2.79 to 2.60 eV. It is worth noting that Fe 0 plays an important role in accelerating electron transfer speed and efficiency between P-CN and EGC. The·O 2 − and h + were the dominant active substances for TC degradation . Moreover, P-CN/Fe 0 @EGC catalyst could be used repeatedly for at least 7 cycles with high TC removal efficiency. This study may pave a new way on designing high efficient ternary hybrid photocatalyst for antibiotic degradation.