Nanoplate-Assembled Yb/Er-BiOBr Microspheres for Durable Self-Cleaning Photocatalytic Coatings

Abstract

This study addresses the efficient and safe purification of low-concentration atmospheric NO. A Yb/Er-codoped nanostructured BiOBr was synthesized via a solvothermal method, and a composite superhydrophobic coating (FSBE) was fabricated by a layer-by-layer spraying strategy using epoxy resin, nano-SiO2, and perfluoroalkyltrimethoxysilane, achieving integrated high photocatalytic activity and excellent micronano-structured superhydrophobicity. The Yb/Er codoping successfully modulates the original layered BiOBr into spherical hollow microspheres assembled from interconnected nanoplates with an optimal Yb/Er ratio of 10:1. This modification enlarges the specific surface area by approximately 7 times, broadens the light response range, and effectively restrains the recombination of photogenerated carriers. The constructed FSBE coating possesses a micronano rough surface with water and ethylene glycol contact angles above 150°, demonstrating superior self-cleaning performance. Under visible light and full-spectrum irradiation, the FSBE coating delivers NO degradation efficiencies of 62.0 and 78.4%, which are 2.85-fold and 1.5-fold higher than those of pure BiOBr, respectively, while efficiently suppressing NO2 accumulation. The coating maintains a photocatalytic efficiency of 65.8% after five cycling tests and exhibits excellent mechanical abrasion resistance and chemical stability. The synergistic effect between the superhydrophobic self-cleaning structure and nanoscale rare-earth-doping-enhanced photocatalysis accounts for its durable NO purification capability. This work provides an insight into the design of high-performance and long-lived photocatalytic nanocoatings for atmospheric environmental remediation.