An insight into a novel calixarene-sensitized Calix@Nb2CTx/g-C3N4 MXene-based photocatalytic heterostructure: Fabrication, physicochemical, optoelectronic, and photoelectrochemical properties

Abstract

The development of highly efficient and cost-effective multifunctional photocatalysts is of current global interest because these photocatalysts have the potential to address the energy and water crisis. Herein, an efficient calixarene-based Calix@Nb2CTx/g-C3N4 (Cx–Nb–CN) photocatalyst was prepared through the formation of covalent bonds between the calixarene (Cx–COCl), g-C3N4 (CN), and Nb2CTx MXene. Enhanced optoelectronic and photoelectrochemical (PEC) properties were observed upon introducing Cx–COCl calixarene and Nb2CTx complexes to the g-C3N4 (CN) photocatalyst. The XPS valence band measurements demonstrated the narrowing of the energy band gap for the composites due to the downshifting and upshifting of the CB and VB, correspondingly. Due to the sensitization effect, the Cx–CN presented superior photocatalytic properties relative to the pristine CN. Moreover, reduced charge transfer resistance (Rct = 110.7 Ω cm2) and the highest photocurrent density (Jp = 7.95 mA/cm2) were observed for the Cx–Nb–CN–5 heterostructure. The Schottky-heterostructures Cx–Nb–CN–1, Cx–Nb–CN–3, and Cx–Nb–CN–5 presented high linear sweep current densities (JLSV) of 8.61, 12.39, 14.04 mA/cm2 signifying excellent light utilization and efficient separation of charge carriers, respectively. The fabricated photocatalyst exhibits excellent physicochemical and photocatalytic properties with the potential to facilitate host-guest complexation towards environmental detoxification and energy conversions.

Keywords

• Calixarene
• MXene
• Host-guest
• Schottky-junction
• Photocatalysis
• Sensitizers