Electrospun one-dimensional graphitic carbon nitride-coated carbon hybrid nanofibers (GCN/CNFs) for photoelectrochemical applications

Abstract

Coupling of graphitic carbon nitride (GCN) with electrospun carbon nanofibers (CNFs) enhanced the photoelectrochemical (PEC) performance of a pristine GCN photoanode. Polyacrylonitrile (PAN) was electrospun to form fibers that were then carbonized to form one-dimensional (1D) CNFs, which were then used to fabricate the GCN structure. The optimum GCN/CNFs hybrid structure was obtained by controlling the amount of GCN precursors (urea/thiourea). The surface morphology of the hybrid structure revealed the coating of GCN on the CNFs. Additionally, X-ray photoelectron spectroscopy, Fourier-transform infrared spectroscopy, and X-ray diffraction confirmed the phases of the GCN/CNFs hybrids. PEC results showed a higher photocurrent of 3 mu A for the hybrid compared with that of 1 mu A for the pristine GCN. The high photocurrent for the hybrid structures indicated the formation of heterojunctions that resulted from a lower recombination rate of charge carriers. Moreover, UTh0.75 (0.075 g of urea and 0.075 g of thiourea) hybrid sample showed the highest performance of hydrogen generation with its numerical value of 437 mu mol/g, compared to those of UTh0.1 (0.1 g of urea and 0.1 g of thiourea) and UTh0.05 (0.05 g of urea and 0.05 g of thiourea) composite samples. This higher hydrogen production could be explained again with successful formation of heterojunctions between GCN and CNFs. Overall, we report a new approach for obtaining 1D hybrid structures, having better PEC performance than that of pristine GCN. These hybrids could potentially be used in energy-related devices.