Catalytic Activation Coupled Regulation of Carbon Structural Domains Enhances the Performance of Capacitive Deionization Purification of Cu ²⁺

The efficient purification of Cu²⁺-contaminated wastewater poses a formidable challenge. Capacitive deionization (CDI) technology, which operates on the principle of electrochemical capacitance, has emerged as a promising candidate for serving as a key technology to address this problem. In this work, chitosan is employed as a carbon precursor for the fabrication of a CDI carbon electrode (CoZn-C). This electrode features a high specific surface area and short-range ordered carbon domains, which are achieved through the strategic utilization of basic carbonate templates to induce site-occupying effects, coupled with the synergistic catalysis of metal. Importantly, benefiting from sufficient electrochemical adsorption active sites and the carbon structural channels that facilitate rapid Cu²⁺ transport, the constructed symmetric CoZn-C//CoZn-C CDI device demonstrates excellent purification capability for Cu²⁺. The adsorption capacity and removal efficiency of the CDI electrode for Cu²⁺ are as high as 124.3 mg g^-1 and 94.5%, respectively (at 1.2 V, 50 mg L^-1). The electrochemical capture of Cu²⁺ by CoZn-C CDI electrodes is achieved through the coupling effect of the electrical double layer and electro-reduction deposition. Accordingly, the carbon domain regulation method offers a new strategy for designing and constructing high-efficiency CDI carbon electrodes for the heavy metal ion wastewater purification.