Developing an understanding of structure–activity relationships and reaction mechanisms of catalytic processes is critical to the successful design of highly efficient catalysts. As a fundamental reaction in fuel cells, elucidation of the oxygen reduction reaction (ORR) mechanism at Pt(hkl) surfaces has remained a significant challenge for researchers. Here, we employ in situ electrochemical surface-enhanced Raman spectroscopy (SERS) and density functional theory (DFT) calculation techniques to examine the ORR process at Pt(hkl) surfaces. Direct spectroscopic evidence for ORR intermediates indicates that, under acidic conditions, the pathway of ORR at Pt(111) occurs through the formation of HO₂*, whereas at Pt(110) and Pt(100) it occurs via the generation of OH*. However, we propose that the pathway of the ORR under alkaline conditions at Pt(hkl) surfaces mainly occurs through the formation of O₂⁻. Notably, these results demonstrate that the SERS technique offers an effective and reliable way for real-time investigation of catalytic processes at atomically flat surfaces not normally amenable to study with Raman spectroscopy.

对催化过程的结构-活性关系和反应机理的理解对于成功设计高效催化剂至关重要。作为燃料电池中的基本反应，阐明Pt（hkl）表面的氧还原反应（ORR）机理仍然是研究人员面临的重大挑战。在这里，我们采用原位电化学表面增强拉曼光谱（SERS）和密度泛函理论（DFT）计算技术来检查Pt（hkl）表面的ORR过程。ORR中间体的直接光谱证据表明，在酸性条件下，ORt在Pt（111）处的路径通过HO ₂的形成而发生*，而在Pt（110）和Pt（100）时，它是通过生成OH *发生的。然而，我们建议，在碱性条件下的ORR在铂（通路HKL）面为主到O的形成发生₂ ^- 。值得注意的是，这些结果表明，SERS技术为实时研究通常不宜用拉曼光谱研究的原子平面上的催化过程提供了一种有效且可靠的方法。