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

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-MoSe_x/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 Ti₃C₂T_x 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 (H_ad) and hydroxyl (OH_ad). Remarkably, N-MoSe_x/Ti₃C₂(OH)_x presents much more negative Zeta potential than the counterpart without alkalization treatment, which efficiently promotes OH_ad transfer (OH_ad + e⁻ ⇌ OH⁻) during the second stage of the Volmer step, indicating further accelerating sluggish kinetics of the whole Volmer step. With these benefits, N-MoSe_x/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.