Enhanced Electrochemical Performance and Theoretical Insights of Ni-Intercalated Ti3C2Tx MXene

Two-dimensional MXenes are renowned for their remarkable electrical conductivity and electrochemical activity making them highly promising for electrode applications. However, the restacking of MXene nanosheets impairs their functionality by reducing active sites and obstructing ionic transport. This study presents a facile synthesis approach for nickel-intercalated MXene, designed to enhance surface reactivity, avoid restacking, and achieve improved electrochemical performance. Electrochemical studies revealed that the nickel-MXene hybrid showed better cycling stability, retaining 83.7% of its capacity after 10 000 cycles and attaining an energy density of 26 Wh kg-1 at a power density of 1872 W kg-1. It also exhibited overpotentials of 109 and 482 mV at 10 and 100 mA cm-2, respectively, in the hydrogen evolution reaction. To predict the structural and electrical alterations caused by nickel inclusion, as well as to understand the intercalation mechanism, spin-polarized density functional theory calculations were carried out. The theoretical results showed an improved carrier concentration for nickel-MXene. Nickel-MXene possessed superior electronic characteristics and surplus active sites with hexagonal closed-packed (hcp) edge sites, which enhanced electrochemical properties. Our results demonstrate that nickel intercalation prevents the restacking of MXene but also significantly improves their electrochemical characteristics, making them ideal for energy storage and catalytic applications.