MoNi alloys as excellent alkaline hydrogen evolution reaction (HER) electrocatalysts benefit from activated Mo-based polymerides for optimizing hydrogen desorption of Ni site. Mo-based polymerides are transformed from adsorbed MoO₄²⁻, which is formed by dissolved Mo. However, the dissolution behavior of Mo is uncontrollable and adsorbed MoO₄²⁻ is limited, resulting in reduced activity of the MoNi alloys. Herein, we reported a unit cell activation strategy to prepare activated MoO_x species in MoNi (MoO_x/MoNi) alloy for boosting performance in alkaline HER. Characterization by Raman spectroscopy shows that activated MoO_x species in MoNi alloy are mainly derived from MoO₄ tetrahedrons of the β-NiMoO₄ under HER, which have strong correlation with the HER performance of the catalyst. The obtained MoO_x/MoNi performs a brilliant HER activity with a low overpotential and Tafel slope of 35 mV@10 mA cm⁻² and 58 mV dec⁻¹, respectively, even surpassing commercial Pt/C. As revealed by a series of characterization techniques and theoretical methods, the brilliant HER activity can be ascribed to both the capacity of MoO_x on adjusting the hydrogen desorption of Ni site and the intrinsic property of the MoNi alloy. Significantly, activating MoO₄ tetrahedrons to MoO_x species is an efficient way to replace the self-dissolution and restructure of Mo in MoNi alloy, which could effectively minimize the adverse effect of dissolved Mo on the catalytic activity of MoNi alloy. This work demonstrates the activation process of MoO₄ tetrahedrons to MoO_x species, providing a new insight into designing and fabricating high-performance HER catalysts by unit cell activation instead of self-dissolution and restructure.

MoNi 合金作为优异的碱性析氢反应 (HER) 电催化剂受益于活化的 Mo 基聚合物以优化 Ni 位点的氢解吸。_{Mo基聚合物由吸附的MoO 4} ^2-转化而成，MoO 4 2- 由溶解的Mo形成。然而，Mo的溶解行为是不可控的，吸附的MoO ₄ ^2-是有限的，导致MoNi合金的活性降低。在此，我们报道了一种晶胞活化策略，用于在 MoNi (MoO _{x /MoNi) 合金中制备活化的 MoO x}物种，以提高碱性 HER 的性能。拉曼光谱表征表明，MoNi合金中活化的MoO _x物种主要来源于MoO ₄HER下β-NiMoO ₄的四面体结构与催化剂的HER性能有很强的相关性。获得的 MoO _x /MoNi 具有出色的 HER 活性，具有低过电位和 Tafel 斜率，分别为 35 mV@10 mA cm ^-2和 58 mV dec ^-1，甚至超过商业 Pt/C。正如一系列表征技术和理论方法所揭示的那样，出色的 HER 活性可归因于 MoOx 调节 Ni 位点氢解吸的能力_和MoNi 合金的本征性质。重要的是，将 MoO ₄四面体激活为 MoO _x物种是取代Mo在MoNi合金中自溶重构的有效途径，可以有效减少溶解的Mo对MoNi合金催化活性的不利影响。_{这项工作展示了 MoO 4}四面体到 MoO _x物种的活化过程，为通过晶胞活化而不是自溶解和重组来设计和制造高性能 HER 催化剂提供了新的见解。