Photocatalytic degradation of ethylene in cold storage using the nanocomposite photocatalyst MIL101(Fe)-TiO2-rGO

To maintain the quality of harvested fruits and vegetables in a closed refrigerated environment, a novel nanocomposite photocatalyst MIL101(Fe)-TiO2-rGO (MTR) for ethylene degradation was synthesized. The characterization of MTR was analyzed by X-ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), Raman spectroscopy, X-ray Photoelectron Spectroscopy (XPS) and High-resolution transmission electron microscope (HRTEM). Moreover, with the good conductivity of rGO, MTR had the smallest band gaps according to ultraviolet–visible solid diffuse reflection (UV–Vis DRS) analysis; this small band gap size improved the utilization of light. According to the results of the photoluminescence spectra and electrochemical impedance spectra, the charge transfer resistance and transient photocurrent of MTR were improved. The redox process of Ti4+/Ti3+ from TiO2 and Fe3+/Fe2+ from MIL101(Fe) efficiently prevented the recombination of e--h+ pairs. In this cycle, oxidative active substances (•O2−) were provided, which played a key role in the ethylene degradation of MTR. Additionally, MTR has excellent gas adsorption capacity, and the photocatalytic degradation rate of C2H4 by MTR was 2.07 × 10-4 min−1, which is better than that of other photocatalysts. Furthermore, the photocatalytic activity of MTR was still stable after 4 times of recycling, indicating the potential to maintain the quality of horticultural products after harvesting.