Tuning intermediate adsorption energy by shifting the d-band center offers a powerful strategy to tailor the reactivity of metal catalysts. Here we report a potential sweep method to grow Pd layer-by-layer on Au with the capability to in situ measure the surface structure through an ethanol oxidation reaction. Spectroscopic characterizations reveal charge-transfer induced valence band restructuring in the Pd overlayer, which shifts the d-band center away from the Fermi level compared to bulk Pd. Precise overlayer control gives the optimal bimetallic surface of two monolayers (ML) Pd on Au, which exhibits more than 370-fold mass activity enhancement in oxygen reduction reaction (at 0.9 V vs. reversible hydrogen electrode) and 40 mV increase in half-wave potential compared to the Pt/C. Tested in a homemade Zn–air battery, the 2-ML-Pd/Au/C exhibits a maximum power density of 296 mW/cm² and specific activity of 804 mAh/g_Zn, much higher than Pt/C with the same catalyst loading amount.

中文翻译：

---

用于促进氧还原催化的双金属电子效应的原位精确调节

通过移动 d 带中心来调整中间吸附能提供了一种强大的策略来定制金属催化剂的反应性。在这里，我们报告了一种潜在的扫描方法，可以在 Au 上逐层生长 Pd，并能够原位通过乙醇氧化反应测量表面结构。光谱表征揭示了 Pd 覆盖层中电荷转移引起的价带重构，与体 Pd 相比，这使 d 带中心远离费米能级。精确的覆盖层控制提供了 Au 上两个单层 (ML) Pd 的最佳双金属表面，在氧还原反应中表现出超过 370 倍的质量活性增强（0.9 V 与可逆氢电极）和 40 mV 的半波增加与 Pt/C 相比的潜力。在自制的锌空气电池中测试，2-ML-Pd/Au/C 的最大功率密度为 296 mW/cm ²，比活性为 804 mAh/g _Zn，远高于使用相同催化剂的 Pt/C装载量。