Simultaneously achieving enhanced water adsorption and rapid adsorbed hydroxyl transfer toward MXene-based materials for highly efficient alkaline electrocatalytic hydrogen evolution

Abstract

MXenes can be employed as the ideal platform for loading active materials for realizing the efficient hybrid electrocatalysts toward hydrogen evolution reaction (HER) originating from the unique layered structure, high specific surface area, excellent electrical conductivity, reliable stability, and strong interaction with loading materials. However, the influence of surface modification on the microstructures of MXenes remains to be revealed. More importantly, how the surface functional groups accelerate alkaline HER remains to be further explored. Herein, we have demonstrated a strategy for utilizing Ti3C2(OH)x as a substrate to load MoSe2 nanosheets with abundant active sites (N-MoSex/Ti3C2(OH)x) by the alkalization treatment at room temperature coupled with the hydrothermal method for highly efficient HER. In our strategy, abundant hydroxyl groups have been successfully introduced into Ti3C2(OH)x by the KOH treatment for Ti3C2Tx and subsequent hydrothermal method. Therefore, the as-developed strategy synergistically increases the hydrophilicity of MXene. This is advantageous for the adsorption of water due to its being thermodynamically favorable. Furthermore, active materials compositing with Ti3C2(OH)x can significantly decrease the energy barrier of the first stage of the Volmer step, which favors the water dissociation into the adsorbed hydrogen atom (Had) and hydroxyl (OHad). Remarkably, N-MoSex/Ti3C2(OH)x presents much more negative Zeta potential than the counterpart without alkalization treatment, which efficiently promotes OHad transfer (OHad + e− ⇌ OH−) during the second stage of the Volmer step, indicating further accelerating sluggish kinetics of the whole Volmer step. With these benefits, N-MoSex/Ti3C2(OH)x exhibits excellent alkaline HER activity. Our results open up an innovative insight into enhancing the HER activity of MXene-based materials from the aspect of the alkalization treatment coupled to compositing with active materials for highly efficient alkaline HER.