Proton exchange membrane fuel cells (PEMFCs) utilize hydrogen for electricity production, but the high cost of platinum catalysts is a key obstacle. This article proposes a novel tandem electrocatalysis approach to improve the efficiency of the hydrogen oxidation reaction (HOR). By developing the Pt1-Ru/C electrocatalyst, consisting of ruthenium nanoclusters decorated with platinum single atoms, significant advancements in reducing platinum group metal content were achieved. Experimental results confirmed the decoupling of the HOR process and showcased hydrogen spillover from ruthenium to platinum sites. Structural characterizations revealed the unique catalyst structure, with Pt single atoms anchored on Ru nanoclusters. The Pt1-Ru/C catalyst demonstrated remarkable performance in PEMFCs with a peak power density of 1.91 W/cm² and high anodic mass activity. The study provides insights into enhancing fuel cell efficiency by utilizing innovative catalyst designs and leveraging hydrogen spillover mechanisms.