Molecular engineering assembly of mesoporous carbon onto Ti3C2Tx MXene for enhanced lithium-ion storage

Abstract

The rational construction of Ti₃C₂T_x MXene-based composites has been deemed as a popular way to improve their electrochemical energy storage performances owing to the unique two-dimensional (2D) structure, excellent conductivity, and good flexibility. However, it remains a major challenge to assemble mesoporous carbon onto Ti₃C₂T_x with fewer oxygen-containing groups by using surfactants with short hydrophilic segments. In the work, we propose a molecular engineering assembly strategy for the growth of N,P co-doped mesoporous carbon onto Ti₃C₂T_x nanosheets (NPMC/Ti₃C₂T_x) under the assistance of phytic acid by using melamine-formaldehyde resin and pluronic P123 (PEO₂₀PPO₇₀PEO₂₀) as the carbon/nitrogen source and soft template, respectively. The detailed investigations reveal that phytic acid with abundant hydroxyl groups can effectively enhance the hydrogen bond interactions among P123, carbon precursor, and Ti₃C₂T_x nanosheets, thus ensuring the efficient assembly of mesoporous carbon onto Ti₃C₂T_x. The obtained NPMC/Ti₃C₂T_x composite demonstrates a set of merits, including cylindrical mesopore, N,P co-doping, and a good combination of mesoporous carbon and Ti₃C₂T_x nanosheets. As a result, it exhibits an improved lithium-ion storage performance, delivering a high reversible capacity of 556.3 mA h g⁻¹ after 100 cycles at 0.1 A g⁻¹. The present work provides a feasible molecular engineering assembly route for the rational design of high-performance Ti₃C₂T_x MXene-based electrodes.