Recyclable Nanoscale Zero Valent Iron Doped g-C3N4/MoS2 for Efficient Photocatalysis of RhB and Cr(VI) Driven by Visible Light

Photocatalytic materials for environmental remediation of organic pollution and heavy metals require not only a strong visible light response and high photocatalytic performance, but also the regeneration and reuse of catalysts. In this work, a ternary hybrid structure material of a nanoscale zero valent iron (Fe-0) doped g-C3N4/MoS2 layered structure (GCNFM) was synthesized by a facile strategy. Compared with the pure GCN, GCNM, and Fe-GCN, the photodegradation efficiency of the GCNFM toward the RhB and Cr(VI) under visible light is considerably enhanced, to 98.2% for RhB and 91.4% for Cr(VI), respectively. In addition, the reaction rate constants (K-RhB and K-Cr) of GCNFM are much higher than those of GCN, GCNM, and Fe-GCN, which is attributed to the fact that Fe-0 and MoS2 composited with GCNM promote the separation of photogenerated electron-hole pairs. Moreover, with the loading of MoS2 and/or Fe-0, the holes could displace the O-center dot(2-) as the main reactive oxygen species in GCN. GCNFM maintains an efficient degradation ability to both RhB and Cr(VI) after several cycles, in spite of the fact that normally Fe-0 will be consumed and deactivated with the reduction proceeding as previously reported. This suggests that the photogenerated electrons, in response, can reduce the Fe(III)/Fe(II) to Fe-0, inducing regeneration and reuse of Fe-0. We anticipate this work can provide a good example for the design of efficient, visible light driven, and recyclable photocatalysts for environmental remediation of both organic pollution and heavy metals.