Recycling noble metal waste into catalytic wealth: In-situ SERS monitoring catalytic systems based on microporous hydrazone covalent organic frameworks materials.

This study focuses on the development of an integrated analytical platform with in situ surface-enhanced Raman spectroscopy (SERS) monitoring capabilities, achieved through the design of a dual-functional, two-dimensional microporous covalent organic framework (COF). The hydrazone-functionalized COF not only exhibits selective recognition for Au(III)/Pt(IV) ions but also achieves efficient recovery of Au(III) from the leachate of waste electronic components, with a recovery efficiency of 95.73 %. By harnessing the enzyme-like catalytic activity of the COF@Au composite and the synergistic combination of COF's confinement effects with the localized surface plasmon resonance of Au nanoparticles, we created enhanced electromagnetic field regions on the material surface. This configuration enables real-time SERS tracking of reactant-product evolution during the reduction of 4-nitrothiophenol (4-NTP), with a reaction rate constant of 0.0181 s^-1. This integrated platform combines precious metal recovery reactions, catalytic processes and in-situ SERS monitoring (" recovery - catalysis - monitoring "), establishing a new paradigm of green and real-time tracking analysis.