Modifying delafossite silver ferrite with polyaniline: Visible-light-response Z-scheme heterojunction with charge transfer driven by internal electric field

Polyaniline (PANI), a conductive polymer with a delocalized pi-conjugated structure, high visible light absorption coefficient and superior charge carrier transfer, has been widely used in combination with other semiconductors to improve photocatalytic performance. In this work, novel PANI/AgFeO2 photocatalysts with visible light photocatalytic performance were successfully synthesized by in situ deposition of AgFeO2 nanoparticles on the surface of PANI. The optimal PANI/AFO-0.2 catalyst resulted the highest photocatalytic performance, about 91.8% of TC was degraded after 1 h of visible light irradiation, the degradation rate constant of which was 2.4 and 15.5 times than that of single AgFeO2 and PANI, respectively. The enhanced photocatalytic performance was attributed to the synergistic effect of enhanced visible light absorption, high specific surface area and excellent charge transfer. Most importantly, based on the comprehensive analysis of the Fermi level and bandgap structure of PANI and AgFeO2, it was found that the internal electric field (IEF) established at the contact interface of PANI and AgFeO2 caused photogenerated electrons and holes to migrate along a path similar to the letter "Z". Therefore, the photogenerated electrons in the CB of AgFeO2 recombined with the equivalent holes generated from the HOMO of PANI, indicating that PANI can also act as an electron acceptor to maximize the strong reducibility of its CB-electrons, which was reported for the first time. As a result, strongly reduced electrons and oxidized holes were retained in PANI and AgFeO2, respectively, leading to an enhanced photocatalytic TC de-gradation performance. This work provided a novel photocatalyst with excellent visible light photocatalytic performance and investigated the mechanism of interface charge transfer.