Aerosol self-assembly synthesis of g-C3N4/MXene/Ag3PO4 heterostructure for enhanced photocatalytic degradation of tetracycline hydrochloride

In this work, the S-scheme heterojunction of g-C3N4/MXene/Ag3PO4 (PCN/M/AP) was successfully constructed via an aerosol self-assembly procedure, in which MXene was employed as the electron mediator. The photocatalytic activity towards the degradation of tetracycline hydrochloride (TC) was found to increase with the mass ratios of MXene to g-C3N4 in the nanocomposites, as MXene dosage increased from 3 wt% to 7 wt%, degradation rates of TC also enhanced from 53.79% to 88.40% at 60 min. And the rate constant value of PCN/M/AP was approximately 4.3 higher than that of the pristine g-C3N4 under visible light illumination, due to the formed of MXene-mediated S-scheme heterojunctions that facilitated separate and transfer of the photogenerated electron-hole pairs. Moreover, the photocatalytic performance of PCN/M/AP toward TC was still maintained 83.80% after five successive recycles. And XRD, XPS and TEM clearly revealed excellent structure stability of PCN/M/AP during the photocatalytic process. The mechanism studies demonstrated that the center dot O-2(-) displayed a major role in TC degradation, and h(+) and center dot OH also affected the removal efficiency greatly. Therefore, this work provides a new insight into the construction of high-performance S-scheme photocatalytic system by using MXene as an electron mediator.

Automated summary

In this work, a S-scheme heterojunction of g-C3N4/MXene/Ag3PO4 (PCN/M/AP) was successfully constructed, in which MXene was used as an electron mediator. The photocatalytic activity towards tetracycline hydrochloride degradation was enhanced by increasing the mass ratio of MXene to g-C3N4 in the nanocomposites. The formed MXene-mediated S-scheme heterojunctions facilitated the separation and transfer of photogenerated electron-hole pairs, leading to higher rate constant value compared to pristine g-C3N4.