Oxygen-Functionalized Ultrathin Ti3C2Tx MXene for Enhanced Electrocatalytic Hydrogen Evolution

Two-dimensional (2D) transition-metal carbides (MXenes) are widely adopted as potential electrocatalysts for the hydrogen evolution reaction (HER) owing to their metallic conductivity, rich tunable surface chemistry, and atomic thickness with highly exposed active sites. Previously published theoretical results indicate that MXenes functionalized entirely with oxygen have lower G(H*) for HER. However, MXenes contain many terminal F groups on the basal plane, which is detrimental to the HER. Herein, the development of an ultrathin Ti3C2 MXene nanosheet fully functionalized with oxygen is reported for the HER. The obtained oxygen-functionalized Ti3C2 (Ti3C2Ox) exhibits a much higher HER activity (190mV at 10mAcm(-2)) than that of Ti3C2Tx (T=F, OH, and O). The improved HER performance is attributed to the highly active O sites on the basal plane of Ti3C2Tx MXenes. This study paves way for electrocatalytic applications of MXene materials by tuning their surface functional groups.