Developing high-performance electrocatalysts with in-depth understanding in reaction mechanisms require not only delicate synthetic technologies, but also advanced analytical methodologies. While catalytic performance can be boosted through the construction of porous nanostructures for enlarged surface area, mechanism studies generally depend on sophisticated in-situ characterization techniques. In the present work, we report a hierarchically porous nanostructure of chromium-doped nickel disulfide as an active electrocatalyst for water oxidation, which exhibits a low overpotential of 207 mV to drive 10 mA cm⁻² in alkaline medium. The surface evolution at different reaction stages is revealed utilizing specifically designed ex-situ characterization approaches. An irreversible self-reconstruction from Cr-doped NiS₂ to Cr, S co-doped Ni(OH)₂ followed by a reversible transformation into NiOOH is observed in cyclic voltammetry processes, indicating that NiS₂ plays a key role as pre-catalyst to generate highly active sites for electrocatalytic water oxidation.

开发对反应机理有深入了解的高性能电催化剂不仅需要精细的合成技术，还需要先进的分析方法。虽然可以通过构建多孔纳米结构以扩大表面积来提高催化性能，但机理研究通常依赖于复杂的原位表征技术。在目前的工作中，我们报道了一种掺杂铬的二硫化镍的分级多孔纳米结构作为水氧化的活性电催化剂，其在碱性介质中表现出 207 mV 的低过电位以驱动 10 mA cm ^-2。不同反应阶段的表面演变利用专门设计的非原位表征方法。在循环伏安法过程中观察到从 Cr 掺杂的 NiS ₂到 Cr、S 共掺杂的 Ni(OH) ₂的不可逆自重构，然后可逆地转变为 NiOOH，表明 NiS ₂作为预催化剂起着关键作用。产生用于电催化水氧化的高活性位点。