Accelerating ion diffusion kinetics with an intensified interfacial electric field for efficient hybrid capacitive deionization

Abstract

The interfacial electric field (IEF) represents a cutting-edge strategy for enhancing ion diffusion kinetics, pivotal in various technological applications. Despite its extensive use, the mechanisms and strategies for regulating IEF remain underexplored. In this study, we enhanced the IEF in a MnO2-x/g-C3N4 (CN) heterostructure by engineering oxygen vacancies in MnO2, which increased the work function difference between MnO2 and CN. The increased work function difference effectively lowers the energy barrier for electron transfer at the heterostructure interface, thereby intensifying the IEF. The enhanced IEF subsequently provides a more potent driving force, facilitating ion movement within the electrode materials during the desalination process. The modified MnO2-x/CN heterostructure demonstrates a notable salt removal capacity of 45.5 mg g−1 and an impressive salt removal rate of 4 mg g−1 min−1, under an operational voltage of 1.2 V in a 500 mg/L NaCl solution. This research not only deepens our understanding of IEF modulation in materials but also sets the stage for the development of high-performance electrodes for hybrid capacitive deionization systems.