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
Mitra Saffari, Zahra Hagheh Kavousi, Massomeh Ghorbanloo, Amr A. Nada, Maged F. Bekheet, Djamel Bezzerga, Jisang Hong, Ali Morsali, Yaovi Holade, Roman Viter, Heba H. El-Maghrabi, Rasha Hosny, Fathi S. Soliman, Igor Iatsunskyi, Emerson Coy, Mikhaël Bechelany
Abstract
The one-dimensional CuO/TiO 2 heteroarchitectures demonstrate remarkable visible-light photocatalytic activity for water splitting. In fact, their performance is significantly enhanced, exhibiting a photocatalytic activity that is more than 400 times higher than pristine TiO 2 nanofibers. This enhancement can be attributed to the hetero-junction between CuO and TiO 2 , which plays a crucial role in improving the separation of photogenerated electrons and holes. The coupling effect between TiO 2 and copper oxide contributes to the efficient utilization of visible light for photocatalysis. • The study employs MOF-assisted synthesis to create CuO/TiO 2 nanofibers to address interface resistance in p-n heterojunctions. • XPS shows Cu in the +II valence state on TiO 2 nanofibers. • The CuO-TiO 2 nanofibers exhibit bandgaps ranging from 3.08 to 2.83 eV, crucial for improving light-harvesting capacity. • The CuO/TiO 2 photocatalyst (1.5 mol% CuO) showed peak activity at 45.6 mmol · g −1 ·h −1 , an impressive 400 times more than pure TiO 2 nanofibers. • One-dimensional nanostructures demonstrated high recyclability without compromising efficiency. 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/TiO 2 nanofibers (NFs) with homogeneity of copper 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 TiO 2 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-TiO 2 NFs heterostructure was uniform. The bandgaps of the CuO-TiO 2 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 is 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 TiO 2 . The CuO/TiO 2 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 TiO 2 nanofibers. Owing to the one-dimensionality of nanostructures, the prepared CuO-based TiO 2 NFs had high recyclability without lessening the efficiencies of photocatalytic activity.