Electrodeposition cobalt sulfide nanosheet on laser-induced graphene as capacitive deionization electrodes for uranium adsorption

It has been proved that capacitive deionization (CDI) technology possesses a significant potential for uranium capture. However, the CDI performance has been limited by the complex preparation process of the electrodes and the poor adhesion between electrode materials and collectors. Here we combine the laser-induced graphene (LIG) and the electrodeposition to develop the LIG/cobalt sulfide (LIG/Co4S3) electrodes with good adsorption performance. The obtained LIG6/Co4S3-15 electrode has both electrical double layers (EDLs) and pseudocapa-citance properties, with a specific capacitance of 24.27 F g-1, which is 1.82 times higher than that of LIG6 (13.36 F g-1). The LIG6/Co4S3-15 electrode exhibited a high adsorption capacity of 2702.79 mg g-1. The advantages of this electrode preparation method are mainly attributed to the synergistic effect of the following aspects: (i) simplified graphene preparation by avoiding wet chemistry and post-treatment steps; (ii) simplified tedious electrode preparation such as electrode slurry distribution and sheet coating; (iii) the three-dimensional structure of LIG provides not only the conductive network but also the site for Co4S3 nanosheet growth, thus avoiding nanosheet aggregation. The abundant pore structure of the conductive graphene substrate and the layered structure of the Co4S3 nanosheets enable the LIG6/Co4S3-15 electrode with fast charge/ion transport, high hy-drophilicity and superior pseudocapacitance, allowing uranyl (UO22+) to be firstly electrosorbed, then physico-chemically adsorbed, and finally electrocatalytically reduced/deposited onto the electrode. This study will offer a simple and environmentally friendly method for the synthesis of electrodes and provide a reference for the design of efficient electroadsorption materials.

Automated summary

By combining laser-induced graphene (LIG) and electrodeposition, LIG/cobalt sulfide (LIG/Co4S3) electrodes with good adsorption performance were developed for uranium capture using capacitive deionization (CDI) technology. The advantages of this electrode preparation method include simplified graphene preparation and electrode distribution, as well as the three-dimensional structure of LIG which avoids nanosheet aggregation. This study provides a simple and environmentally friendly method for electrode synthesis and serves as a reference for designing efficient electroadsorption materials.