Overcoming the sluggish kinetics of alkaline hydrogen oxidation reaction (HOR) is challenging but is of critical importance for practical anion exchange membrane fuel cells. Herein, abundant and efficient interfacial active sites are created on ruthenium (Ru) nanoparticles by anchoring atomically isolated chromium coordinated with hydroxyl clusters (Cr₁(OH)_x) for accelerated alkaline HOR. This catalyst system delivers 50-fold enhanced HOR activity with excellent durability and CO anti-poisoning ability via switching the active sites from Ru surface to Cr₁(OH)_x-Ru interface. Fundamentally different from the conventional mechanism merely focusing on surface metal sites, the isolated Cr₁(OH)_x could provide unique oxygen species for accelerating hydrogen or CO spillover from Ru to Cr₁(OH)_x. Furthermore, the original oxygen species from Cr₁(OH)_x are confirmed to participate in hydrogen oxidation and H₂O formation. The incorporation of such atomically isolated metal hydroxide clusters in heterostructured catalysts opens up new opportunities for rationally designing advanced electrocatalysts for HOR and other complex electrochemical reactions. This work also highlights the importance of size effect of co-catalysts, which should also be paid substantial attention to in the catalysis field.

克服碱性氢氧化反应 (HOR) 的缓慢动力学具有挑战性，但对于实用的阴离子交换膜燃料电池至关重要。_{在此，通过锚定与羟基簇（Cr 1} (OH) _x ）配位的原子分离的铬，在钌（Ru）纳米颗粒上产生丰富且有效的界面活性位点，以加速碱性HOR。_{该催化剂体系通过将活性位点从 Ru 表面切换到 Cr 1} (OH) _x -Ru 界面，将 HOR 活性提高 50 倍，并具有出色的耐久性和 CO 抗中毒能力。与仅关注表面金属位点的传统机制根本不同，孤立的 Cr ₁ (OH) _x可以提供独特的氧物质来加速氢或CO从Ru溢出到Cr ₁ (OH) _x。_{此外，来自Cr 1} (OH) _x的原始氧物质被证实参与了氢氧化和H ₂ O的形成。在异质结构催化剂中加入这种原子分离的金属氢氧化物簇为合理设计用于 HOR 和其他复杂电化学反应的先进电催化剂开辟了新的机会。这项工作还强调了助催化剂尺寸效应的重要性，这在催化领域也应引起重视。