Investigation of solar-induced photoelectrochemical water splitting and photocatalytic dye removal activities of camphor sulfonic acid doped polyaniline-WO3-MWCNT ternary nanocomposite

The camphor sulfonic acid doped polyaniline-WO3-multiwall carbon nanotube(CSA PANI-WO3-CNT)ternary nanocomposite was synthesized during in-situ oxidative polymerization and characterized by Fourier transform infrared(FTIR)spectroscopy,Raman spectroscopy,X-ray diffraction(XRD),Field emission scanning electron microscopy(FESEM),X-ray photoelectron spectroscopy(XPS),Transmission electron microscopy(TEM),and Energy-dispersive X-ray spectroscopy(EDS).The application of CSA PANIWO3-CNT ternary nanocomposite was investigated as the photocatalyst in the degradation of methylene blue dye(MB)and as the noble metal-free photoanode in photoelectrochemical water splitting under solar light irradiation.The degradation percentage of MB dye after 60 min illumination by CSA PANI-WO3-CNT ternary nanocomposite reached 91.40%which was higher than that of pure WO3(43.45%),pure CSA PANI(48.4%)and CSA PANI-WO3 binary nanocomposite(85.15%).The photocurrent density of indium tin oxide(ITO)/CSA PANI-WO3-CNT photoanode obtained 0.81 m A/cm2 at 1.23 V vs.reversible hydrogen electrode under illumination which was 1.27,2.13,and 4.26 times higher than that of the ITO/CSA PANI-WO3(0.64 m A/cm2),ITO/pure CSA PANI(0.38 m A/cm2),and ITO/pure WO3(0.19 m A/cm2).Also,the applied bias photon-to-current efficiency(ABPE)of ITO/CSA PANI-WO3-CNT was obtained 0.11%which showed two-fold,four-fold,and five-fold enhancements compared to the ITO/CSA PANI-WO3,ITO/CSA PANI,and ITO/WO3,respectively.The electrochemical impedance spectroscopy,as well as the Mott-Schottky results,confirmed the better photoelectrocatalytic activity of ITO/CSA PANI-WO3-CNT in comparison with ITO/WO3,ITO/CSA PANI,and ITO/CSA PANI-WO3.The observed improvement in the photocatalytic and photoelectrocatalytic performances of WO3 in the presence of CSA PANI is due to the formation of type-II heterojunction between WO3 and CSA PANI which allows the separation of charge carriers easier and faster.On the other hand,MWCNT addition to the CSA PANI-WO3 nanocomposite provided the conducting substrate for efficient interfacial charge separation as well as transferring.