Two-dimensional Ti₃C₂T_x MXenes have been extensively studied as pseudocapacitive electrode materials. This Letter aims at providing further insights into the charge storage mechanism of the Ti₃C₂T_x MXene electrode in the acidic electrolyte by combining experimental and simulation approaches. Our results show that the presence of H₂O molecules between the MXene layers plays a critical role in the pseudocapacitive behavior, providing a pathway for proton transport to activate the redox reaction of the Ti atoms. Also, thermal annealing of the samples at different temperatures suggests that the presence of the confined H₂O molecules is mainly controlled by the surface termination groups. These findings pave the way for alternative strategies to enhance the high-rate performance of MXenes electrodes by optimizing their surface termination groups.

中文翻译：

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揭示酸性电解质中Ti ₃ C ₂ T _x MXene电极的电荷存储机理

二维Ti ₃ C ₂ T _x MXenes作为伪电容电极材料已得到广泛研究。该信旨在通过结合实验和模拟方法，进一步了解Ti ₃ C ₂ T _x MXene电极在酸性电解液中的电荷存储机理。我们的结果表明，MXene层之间H ₂ O分子的存在在拟电容行为中起着关键作用，为质子传输提供了激活Ti原子氧化还原反应的途径。同样，在不同温度下对样品进行热退火表明，存在受限的H ₂O分子主要由表面终止基团控制。这些发现为优化MXenes电极的表面终止基团以提高MXenes电极的高性能提供了替代策略。