Flower‐Like Al₂O₃/AgBr Nanostructures Prepared from Oil Shale Ash for Improved Catalytic Reduction of 4‐nitrophenol

Abstract 4‐Nitrophenol has significant negative impacts on both aquatic and terrestrial organisms due to its ability to slow down the photosynthesis process and its carcinogenic properties. In this study, oil shale ash residue was utilized as an aluminum source to prepare flower‐like γ‐Al₂O₃/AgBr composite photocatalysts via the hydrothermal synthesis method. The structure and morphology of the materials were characterized using field emission scanning electron microscopy (SEM), Ultraviolet–visible spectroscopy (UV–vis), and X‐ray diffraction (XRD), revealing a well‐structured flower‐like morphology with uniformly dispersed AgBr microspheres within the alumina framework. The catalytic performance for the reduction of 4‐nitrophenol by sodium borohydride was also investigated. Results indicated that the efficient loading of AgBr particles on γ‐Al₂O₃ significantly enhanced the photocatalytic activity, increasing the degradation efficiency from 54.8% for pure AgBr to 93.94% within 4.5 min, with a reaction rate constant of 0.6354 min⁻¹. These findings demonstrate that the composite material's enhanced performance is attributed to the synergistic effects of the heterojunction structure and increased active sites. This research provides a meaningful pathway for the comprehensive utilization of oil shale ash residue and offers a promising approach for the development of efficient photocatalysts for wastewater treatment.