Nb2CTx-MXene partially derived 1D Nb2O5 nanorod/2D Nb2C nanohybrid via interfacial synergy for enhanced capacitive deionization

1D Nb 2 O 5 nanorods grown in situ uniformly on the surface 2D Nb 2 C MXene. • Nb 2 O 5 nanorods act as passivation layers, mitigating MXene restacking and oxidation. • Interfacial charge transfer between Nb 2 O 5 and Nb 2 C accelerates electron kinetics. • The Nb 2 O 5 -Nb 2 C hybrid exhibits excellent desalination performance and cycling stability. Self-stacking and oxidative instability limit the ion accessibility and cycling stability of MXene electrodes in capacitive deionization (CDI). To address these limitations, a controlled partial derivation strategy was used to construct Nb 2 O 5 nanorods on Nb 2 CT x MXene nanosheets, forming 1D Nb 2 O 5 nanorod/2D Nb 2 C heterostructure. The derived Nb 2 O 5 nanorods increased the accessible surface area, provided expanded ion intercalation channels, suppressed Nb 2 CT x restacking, and also acted as a partial passivation layer to inhibit further MXene oxidation. Electrochemical measurements showed that the Nb 2 O 5 -Nb 2 C electrode exhibited higher capacitance and lower charge-transfer resistance than pristine Nb 2 C, suggesting improved interfacial charge transfer behavior and ion storage kinetics. The Nb 2 O 5 -Nb 2 C hybrid delivered a salt adsorption capacity (SAC) of 51.2 mg g −1 at 1.6 V, an average salt removal rate (SAR) of 1.7 mg g −1  min −1 , and retained 90.5% of its initial capacity after 200 cycles. These results indicate that controlled partial oxidation can not only mitigates the instability of Nb 2 C, but also improves ion accessibility, electrochemical kinetics, and cycling durability of Nb-based MXene electrodes for CDI. Download: Download high-res image (360KB) Download: Download full-size image