MOF-derived 3D MnO2@graphene/CNT and Ag@graphene/CNT hybrid electrode materials for dual-ion selective pseudocapacitive deionization

• Published in: Desalination 2023-03, Vol.550, p.116369, Article 116369
• Main Authors: Rangaraj, Vengatesan M., Yoo, Jae-In, Song, Jang-Kun, Mittal, Vikas
• Format: Article
• Language: English
• Subjects: Capacitive deionization; Dual-ions adsorption; Graphene/CNT structure; Pseudocapacitance; Redox-active materials
• ISSN: 0011-9164; 1873-4464
• DOI: 10.1016/j.desal.2023.116369

In the present study, an asymmetric pseudocapacitive deionization (PCDI) system was fabricated using redox-active electrode materials of three-dimensional (3D) MnO2@graphene/CNT (MGC) and Ag@graphene/CNT (AGC) as cathode and anode, respectively. The asymmetric PCDI system owns a dual-ion capture mechanism, resulting in a high desalination capacity. The 3D MGC and AGC active electrode materials have been derived through a facile two-step method. Initially, the Mn-BTC and Ag-BTC were in situ grown on the 3D r-GO/CNT structure through a hydrothermal process, yielding Mn-BTC@r-GO/CNT and Ag-BTC@r-GO/CNT hybrids. Subsequently, high-temperature annealing of these hybrids leads to respective MGC and AGC hybrid nanocomposites. Powder X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) analysis facilities were used to investigate the structure and morphology of the as-prepared hybrid nanocomposites. The as-derived 3D MGC and AGC electrode materials exhibit the high specific capacitance of 496.4 and 206.6 F g−1, respectively, at 1 A g−1 using a 1 M NaCl solution. Furthermore, the MGC (cathode)//AGC (anode) electrode pairs-based PCDI system exhibits remarkable desalination performance with a high salt adsorption capacity of 62.4 mg g−1 and a charge efficiency of 95 % in 1000 ppm NaCl solution at 1.2 V. [Display omitted] •MOF-derived MnO2@graphene/CNT and Ag@graphene/CNT electrodes for PCDI applications•Pseudo capacitive deionization (PCDI) owns a dual-ion capture mechanism.•PCDI system exhibits high salt removal capacity of 62.4 mg g−1.