Copper benzene-1,3,5-tricarboxylate based metal organic framework (MOF) derived CuO/TiO2 nanofibers and their use as visible light active photocatalyst for the hydrogen production

Abstract

Photocatalytic hydrogen generation through water splitting offers a sustainable and renewable approach to producing green and clean hydrogen fuel. However, it is crucial to explore low-cost semiconductor photocatalysts that can effectively capture a broad range of solar radiation. The present study aims to develop photocatalytic CuO/TiO2 nanofibers (NFs) with homogeneity of cupper with titanium in the heterostructures through the metal–organic framework (MOF)-assisted strategy via the electrospinning and subsequent calcination approach. The new methodology enables the fabrication of CuO-modified TiO2 NFs based on HKUST-1 (copper benzene-1,3,5-tricarboxylate, Hong Kong University of Science and Technology-1) as Cu-MOF varying the amounts of HKUST-1. Ultraviolet–visible light diffuses reflectance spectroscopy (DRS), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), Fourier-transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), photoluminescence spectroscopy (PL), X-ray photoemission spectroscopy (XPS) and Raman spectroscopy are employed to assess the structural and morphological characteristics of the prepared NFs. The characterization revealed that the CuO-TiO2 NFs heterostructure was uniform. The bandgaps of the CuO-TiO2 NFs ranged from 3.08 to 2.83 eV based on the Kubelka–Munk function, which is considerable for improving the light-harvesting capacity. The photocurrent technique used to confirm efficiency in charge separation and transfer, as well as a longer lifetime of photo-generated charge carriers effect in photocatalytic activity. In addition, density functional theory calculations were performed to analyze the impact of CuO on the geometric, electronic structure and photocatalytic properties of TiO2. The CuO/TiO2 photocatalyst containing 1.5 mol% of CuO exhibited the highest photocatalytic activity. The hydrogen production rate was exceptional at 45.6 mmol·g−1·h−1, which was a remarkable 400 times higher than that achieved with pure TiO2 nanofibers. Owing to the one-dimensionality of nanostructures, the prepared CuO-based TiO2 NFs had high recyclability without lessening the efficiencies of photocatalytic activity.