Exploring efficient noble-metal-free electrocatalysts for hydrogen evolution reaction (HER) is of great importance to solve the energy crisis. The family of two-dimension transition metal carbides, MXenes, has received a small amount of research, including the reactivity and number of active sites, relative to their extraordinary potential as electrocatalysts for HER. Herein, a model of atomically-thin Ti₂CT_x (where T_x denotes the surface termination groups; -F, -O, -OH) nanosheets with the rich surface fluorine termination groups is put forward to achieve synergistic regulations of both reactivity and number of active sites. Theoretical calculations and electrochemical tests show that the rich surface F terminations can promote the proton adsorption kinetics and reduce the charge-transfer resistance of the Ti₂CT_x nanosheets, leading to the increased reactivity of active sites and favorable electrode kinetics. Besides, the ultrathin thickness of the Ti₂CT_x nanosheets offers high-density active sites for HER. As expected, the rich F-terminated Ti₂CT_x nanosheets exhibit a small onset overpotential of 75 mV and a large exchange current density of 0.41 mA cm⁻². Our discovery adds to the growing potential of MXene-based materials for application in hydrogen evolution reaction.

探索有效的无贵金属电催化剂进行氢气释放反应（HER）对于解决能源危机具有重要意义。二维过渡金属碳化物系列MXenes相对于作为HER的非凡潜力，已经进行了少量研究，包括反应性和活性位点数量。这里，是原子薄的Ti ₂ CT _x（其中T _x表示表面终止基团；提出了具有丰富的表面氟末端基团的-F，-O，-OH）纳米片，以实现反应性和活性位点数量的协同调节。理论计算和电化学测试表明，富集的表面F端基可促进质子吸附动力学并降低Ti ₂ CT _x纳米片的电荷转移阻力，从而导致活性位的反应性增加和有利的电极动力学。此外，Ti ₂ CT _x纳米片的超薄厚度为HER提供了高密度的活性位点。如预期的那样，富F端接的Ti ₂ CT _x纳米片表现出小的起始过电势75 mV和大的交换电流密度0.41 mA cm ^-2。我们的发现增加了基于MXene的材料在氢释放反应中的应用潜力。