Ultrafast Kinetics of 4-Nitrophenol Reduction via Coral-Like Nanostructured Cu Mesh Monitored By Real-Time UV–Vis Absorption Spectroscopy

Abstract

Analyzing ultrafast liquid-phase reactions in real time presents significant challenges owing to their rapid kinetics. In this study, by employing the reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) as a model reaction, we demonstrate the feasibility of real-time kinetic analysis using UV–Vis absorption spectroscopy. This reaction, which was completed within 10 s, was successfully monitored and analyzed to understand the limitations of conventional ultrafast reaction methods and explore steps to overcome them. A novel coral-like ultrasonic-treated Cu (UCu) mesh fabricated via sulfidation and ultrasonic treatments was utilized as the catalyst for this reaction, resulting in a high specific surface area and abundant active sites. The UCu mesh exhibited an apparent rate constant of 0.353 s⁻¹, significantly outperforming other reported catalysts, such as ZnO@Cu (0.043 s⁻¹) and Cu nanowires (0.076 s⁻¹). Compared to Cu and CuS meshes, the UCu mesh demonstrated a 29- to 58-fold improvement in catalytic performance under identical conditions. These results demonstrate the effectiveness of integrating real-time UV–Vis spectroscopy with advanced nanostructured catalysts for ultrafast reaction analyses. This study establishes the UCu mesh as a highly efficient and reusable catalyst with promising applications in environmental and industrial processes requiring rapid catalytic reactions.