Continuous flow synthesis of Ag-PEDOT-COF nanocomposite for sustainable photoreforming of plastic waste and chromium remediation in visible light

Using the freely available solar energy for photocatalytic environmental remediation is a highly sustainable approach. Visible light active heterogeneous photocatalysts are to be developed for driving such reactions. Heterojunction nanocomposites of conjugated polymers with metals as well as other semiconductors are highly active photocatalysts. However, the synthesis of these materials involves multi-step reactions and harsh reaction conditions. Here, we report a single-step continuous flow synthesis of a nanocomposite (Ag@PEDOT-DAAQ-TFPFlow), containing a conducting polymer (PEDOT), silver (Ag) nanoparticles and a covalent organic framework (COF, DAAQ-TFP). The nanocomposite could be synthesised at a lower temperature and in less time when compared to a two-step batch process. Moreover, Ag@PEDOT-DAAQ-TFPFlow exhibited higher surface area and porosity than Ag@PEDOT-DAAQ-TFPBatch. Further, the former has improved ability to absorb light in a broad range, efficiently generate charge carriers and transfer them than the latter as well as Ag@PEDOT and, DAAQ-TFP. Thus, Ag@PEDOT-DAAQ-TFPFlow could be used as an efficient photocatalyst for photoreforming plastic waste to green hydrogen (113.4 mmolgcat-1h-1) and other value-added products such as formate, acetate, terephthalate, and lactate. It is also one of the best visible light active photocatalysts for the reduction of toxic Cr (VI) to Cr (III). Thus, the enhanced mixing profile and better heat/mass transfer in the continuous flow synthesis process enabled us to achieve a highly active photocatalyst.