Recycling e-waste into gold-loaded covalent organic framework catalysts for terminal alkyne carboxylation
Amin Zadehnazari, Florian Auras, Ataf Ali Altaf, Amin Zarei, Ahmad Reza Khosropour, Saeed Amirjalayer, Alireza Abbaspourrad
Abstract
The rising demand for gold requires innovative methods for its recovery from e-waste. Here we present the synthesis of two tetrazine-based vinyl-linked covalent organic frameworks: TTF-COF and TPE-COF that adsorb gold ions and nanoparticles and catalyze the carboxylation of terminal alkynes. These covalent organic frameworks have low band gaps and high photocurrent responses. TTF-COF has an adsorption capacity toward aqueous Au(III) of 2440 mg g–1, and TPE-COF’s Au(III) adsorption capacity is 1639 mg g–1. The gold source is metal flakes isolated from waste computer processing units. Of the gold present, > 99% is selectively captured by TTF-COF whereas only 5% of the Ni and 2% of the Cu in the solution is adsorbed. The Au-loaded covalent organic frameworks catalyze the carboxylation of terminal alkynes and are stable and reusable for six reuse cycles. Our covalent organic frameworks convert e-waste into a valuable catalyst for a useful green organic transformation. The rising demand for gold requires innovative methods for its recovery from e-waste. Here, the authors describe tetrazine-linked covalent organic frameworks loaded with recovered gold from mixed metal e-waste which serve as efficient, reusable catalysts for CO2 carboxylation of alkynes.