Performance of Janus-like type nobel-metal/TiO2 microspherical nanocomposites and application on microplastics photodegradation

Abstract

The persistent environmental pollution caused by microplastics presents a significant challenge, with photocatalytic degradation emerging as a promising solution. However, its efficacy is often limited by ineffective photocarrier separation. This study addresses these limitations by designing Janus-like type photocatalysts comprising silver (Ag) and gold (Au) nanoparticles anchored on hollow TiO₂ microspheres (HTMs) via a photoreduction method. The resulting composite photocatalysts, Ag/HTMs and Au/HTMs, were evaluated for their ability to degrade microplastic polyethylene (PE) films. Morphological and compositional analyses using SEM, EDS, and XPS confirmed the successful loading and oxidation states of Ag and Au nanoparticles. Electrochemical characterizations revealed significantly enhanced photocatalytic activities for HTMs and their Janus-like composites, outperforming the performance of commercial P25 photocatalyst. Notably, Janus-like Ag-5/HTMs and Au-10/HTMs exhibited photocatalytic activities that were 90-fold and 60-fold higher than P25, respectively. Under irradiation, Janus-like Ag-5/HTMs achieved the highest degradation efficiency, mediated by reactive species (·OH, O₂^–·, ¹O₂, and h⁺) under ambient conditions. To further demonstrate its practical application, a device was fabricated by spin-coating Ag-5/HTMs onto spherical activated carbon. When applied to swimming pool water containing 98.20 MP/L of microplastics, achieving a high removal efficiency for microplastics. This study underscores the potential of Janus-like M/HTMs systems for the efficient and sustainable degradation of microplastics, advancing their application in environmental remediation.