Fabrication of ZnO NP/g-C3N4 column brace structure composites and study on NO photocatalytic oxidation removal performance

With the rapid industrial development, air pollution and global climate change have become pressing issues. Addressing the effective removal of nitrogen oxides (NOx), a major contributor to these problems, is crucial. Photo-oxidation technology emerges as a promising solution, offering a new, green method of NOx removal. This technology stands out for its safety, cost-effectiveness, cleanliness, and cycle stability, making it an efficient approach to tackling NOx emissions. In this study, we explore a novel strategy that involves the in-situ growth of ZnO nanodot arrays on surfaces of graphite-phase carbon nitride (g-C3N4) to construct column-supported structure composites. These composites are designed for the photo-oxidation removal of NO under visible light. By employing an ion adsorption reaction, ZnO NP/g-C3N4 column-supported structure composite photo-oxidizers were successfully synthesized with varying ZnO particle mass fractions of 1%, 2.5%, and 5%, respectively. The investigation revealed that introducing ZnO NP significantly increases the specific surface area of the ZnO NP/g-C3N4 composites compared to pure g-C3N4 samples, which have a specific surface area of 31.092 m2·g‒1. Specifically, the 2.5% ZnO NP/g-C3N4 composites exhibited a substantial increase to 58.063 m2·g‒1, while the 1% and 5% ZnO NP/g-C3N4 composites reached 37.141 m2·g‒1 and 42.563 m2·g‒1, respectively. This enhancement in the specific surface area, attributed to the columnar support structure, addresses the stacking issue of the g-C3N4 lamellae in the composites. The resulting structure is stretchier and fluffier, exposing a greater number of reactive sites. Furthermore, the construction of a heterostructure improves the energy band structure of the composites, facilitating the migration and separation of photogenerated carriers, which significantly enhances the photo-oxidation performance. During the NO photo-oxidation removal experiments, the ZnO NP/g-C3N4 composites demonstrated a marked improvement in photo-oxidation efficiency compared to pure g-C3N4. Notably, the 2.5% ZnO NP/g-C3N4 composites achieved a 100% photo-oxidation removal rate of NO, maintaining an effective removal performance across different NO concentrations and exhibiting robust performance in five cycles of stability tests. This study provides an effective strategy for designing and constructing high-performance photo-oxidizers and provides a technical reference for eliminating industrial NO pollutants. In addition, our study introduces a method for the photo-oxidation removal of NO and inspires new approaches in the design and synthesis of composite photocatalysts. By modulating the composition and structure of these composites, their photo-oxidation performance can be further optimized to achieve more efficient and stable pollutant removal. This advancement holds significant implications for environmental protection and sustainable development.