Highly Efficient Metal‐Free Visible Light Driven Photocatalyst: Graphene Oxide/Polythiophene Composite

Graphene oxide/polythiophene (GO/PTh) composites were synthesized by in‐situ polymerization of thiophene (Th) monomers on GO surfaces. Remarkable performance of GO/PTh composites for methylene blue (MB) photo‐degradation under visible light has been achieved by tuning GO/Th ratio and graphene oxidation degrees. 100 % MB degradation was achieved by the composite within 30 min under visible light, its catalytic activity (0.1149 min −1 ) is 382 and 41 times higher than that of PTh (0.0003 min −1 ) and GO (0.0028 min −1 ), respectively. The results of MB adsorption experiment, ultraviolet‐visible (UV‐vis) and photoluminescence (PL) spectra show that combination of GO and PTh increases MB adsorption, decreases the band gap and enhances photo‐electron transfer. The composite with 36 % PTh (at the fed GO/Th weight ratio of 1:2) shows the highest catalytic activity where MB adsorption ability by GO and photo‐electron producing ability by PTh in the composite is well matched. The catalytic activity can be further enhanced by changing graphene oxidation degree by controlling graphite/KMnO 4 ratio and post‐reaction time during GO preparation. Fourier transform infrared (FTIR) spectroscopy and X‐ray photo‐electron (XPS) spectroscopy analyses have shown that increasing oxidation degree of GO leads to a stronger π‐π interaction between GO and PTh and a more electron‐rich PTh, resulting in higher catalytic activity.