Fabrication of a graphene oxide/zeolitic imidazolate framework-8 (GO/ZIF-8) composite for enhanced adsorptive and piezo-assisted photocatalytic removal of organic dyes

Abstract

In this study, a novel porous zeolitic imidazolate framework decorated graphene oxide (GO/ZIF-8) composite was successfully synthesized for adsorptive and catalytic removal of organic dyes from wastewater. The structural and photo-electrochemical characteristics of the GO/ZIF-8 composite were investigated using FTIR, XRD, FESEM, TEM, EDS, BET, UV-Vis DRS, EIS, and PL spectroscopy techniques. The GO/ZIF-8 composite showed a mesoporous crystalline structure with tunable photoelectrochemical properties that had never been studied as an adsorbent and piezo-photocatalyst. It also exhibited a specific surface area and optical bandgap of 804 m² g⁻¹ and 3.60 eV, respectively, facilitating charge transfer and shortening the recombination rate of photo-generated electrons and holes. To study the feasibility of the GO/ZIF-8 composite for adsorption and piezo-assisted photocatalytic degradation of organic dyes, a series of dye removal experiments were carried out under different catalytic conditions. The adsorption kinetics and isotherm revealed that the pseudo-second-order kinetic and the Freundlich isotherm model could better describe the adsorption of dye on the GO/ZIF-8 composite in both dark and light conditions. The catalytic dye degradation under UV and visible light irradiation and ultrasonic vibration also exhibited impressive synergistic piezo-photocatalytic activity of the developed GO/ZIF-8 composite. The piezocatalytic and photocatalytic dye degradation efficiencies using the GO/ZIF-8 composite were found to be 75.9% and 77.2%, respectively, within 90 min, while the piezo-photocatalytic degradation efficiency was observed to be 85.4% at that time. This study opens up a new and efficient strategy for designing and developing highly efficient piezo-photocatalysts with outstanding adsorption capacity for the removal of organic pollutants from wastewater.