Constructing bio-templated 3D porous microtubular C-doped g-C3N4 with tunable band structure and enhanced charge carrier separation

• Main Authors: Mohamed, Mohamad Azuwa, Zain, M. F. M., Jeffery Minggu, Lorna, Kassim, Mohammad B., Saidina Amin, Nor Aishah, Salleh, W. N. W., Salehmin, Mohd. Nur Ikhmal, Md. Nasir, Mohd. Faizal, Mohd. Hir, Zul Adlan
• Format: Article
• Published: Elsevier B.V. 2018
• Subjects: TP Chemical technology
• Online Access: http://eprints.utm.my/id/eprint/84461/; http://dx.doi.org/10.1016/j.apcatb.2018.05.037

For the first time, the bio-templated porous microtubular C-doped (BTPMC) g-C 3 N 4 with tunable band structure was successfully prepared by simple thermal condensation approach using urea as precursors and kapok fibre which provides a dual function as a bio-templates and in-situ carbon dopant. Prior to the thermal condensation process, the impregnation strategies (i.e. direct wet and hydrothermal impregnation) of urea on the treated kapok fibre (t-KF) were compared to obtained well-constructed bio-templated porous microtubular C-doped g-C 3 N 4 . The details on a physicochemical characteristic of the fabricated samples were comprehensively analyze using X-ray diffraction (XRD), Fourier transform infrared (FTIR), X-ray photoelectron spectroscopy (XPS), Field-emission scanning electron microscopy (FESEM), Transmission electron microscopy (TEM), N 2 adsorption-desorption, Thermogravimetric (TGA), and UV-vis spectroscopy. Our finding indicated that the hydrothermal impregnation strategy resulted in well-constructed microtubular structure and more carbon substitution in sp 2 -hybridized nitrogen atoms of g-C 3 N 4 as compared to the direct wet impregnation. Also, compared to pure g-C 3 N 4 , the fabricated BTPMC g-C 3 N 4 exhibited extended photoresponse from the ultraviolet (UV) to visible and near-infrared regions and narrower bandgap. The bandgap easily tuned with the increased t-KF loading in urea precursor which responsible for in-situ carbon doping. Moreover, as compared to pristine g-C 3 N 4 dramatic suppression of charge recombination of the BTPMC g-C 3 N 4 was confirmed through photoluminescence, photocurrent response, and electrochemical impedance spectroscopy. The resultants BTPMC g-C 3 N 4 possesses more stable structure, promoted charge separation, and suitable energy levels of conduction and valence bands for photocatalysis application.