Tuning the local reaction environment is an important and challenging issue for determining electrochemical performances. Herein, we propose a strategy of intentionally engineering the local reaction environment to yield highly active catalysts. Taking Pt^δ− nanoparticles supported on oxygen vacancy enriched MgO nanosheets as a prototypical example, we have successfully created a local acid-like environment in the alkaline medium and achieve excellent hydrogen evolution reaction performances. The local acid-like environment is evidenced by operando Raman, synchrotron radiation infrared and X-ray absorption spectroscopy that observes a key H₃O⁺ intermediate emergence on the surface of MgO and accumulation around Pt^δ− sites during electrocatalysis. Further analysis confirms that the critical factors of the forming the local acid-like environment include: the oxygen vacancy enriched MgO facilitates H₂O dissociation to generate H₃O⁺ species; the F centers of MgO transfers its unpaired electrons to Pt, leading to the formation of electron-enriched Pt^δ− species; positively charged H₃O⁺ migrates to negatively charged Pt^δ− and accumulates around Pt^δ− nanoparticles due to the electrostatic attraction, thus creating a local acidic environment in the alkaline medium.

调整局部反应环境是确定电化学性能的一个重要且具有挑战性的问题。在此，我们提出了一种有意设计局部反应环境以产生高活性催化剂的策略。以负载在富氧空位的 MgO 纳米片上的Pt ^{δ−纳米粒子为例，我们成功地在碱性介质中创造了局部类酸环境，并实现了优异的析氢反应性能。}局部类酸环境通过原位拉曼、同步辐射红外和 X 射线吸收光谱得到证明，该光谱观察到关键的 H ₃ O ⁺中间体出现在 MgO 表面并在 Pt ^{δ−周围积累}电催化过程中的位点。进一步分析证实，形成局部类酸环境的关键因素包括：富含氧空位的MgO促进H ₂ O解离生成H ₃ O ⁺物种；MgO 的 F 中心将其未成对的电子转移到 Pt，导致形成富电子的 Pt ^δ−物种；带正电的 H ₃ O ⁺迁移到带负电的 Pt ^δ−并由于静电吸引而聚集在 Pt ^{δ−纳米粒子周围，从而在碱性介质中形成局部酸性环境。}