Oxygen vacancy-induced interfacial coupling in a 3D Pt-RuO2/rGO heterostructure for superior bifunctional electrocatalysis

Developing highly efficient and durable bifunctional electrocatalysts for both the oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) in acidic environments is vital for advancing proton exchange membrane water electrolysis (PEMWE) technology. Herein, we report the design and synthesis of a three-dimensional Pt-RuO 2 -based catalyst supported on reduced graphene oxide (rGO), denoted as 3D Pt-RuO 2 /rGO, which exhibits outstanding bifunctional electrocatalytic activity by tuning its electronic structure and the binding strength of reaction intermediates. The 3D porous architecture not only facilitates fast charge transfer and mass transport of the catalysts but also increases the exposure of active sites. Remarkably, 3D Pt-RuO 2 /rGO delivers low overpotentials of only 200 mV for OER and 14 mV for HER at 10 mA cm −2 in 0.5 M H 2 SO 4 . It also enables overall water splitting (OWS) at a cell voltage as low as 1.48 V at 10 mA cm −2 , outperforming conventional noble metal-based materials (NMBs). Furthermore, a 3D Pt-RuO 2 /rGO||3D Pt-RuO 2 /rGO MEA delivered a low cell voltage of 1.549 V at 1 A cm −2 and maintained stable operation for 300 h in a PEM single-cell electrolyzer. Operando differential electrochemical mass spectrometry (DEMS) shows that the OER of 3D Pt-RuO 2 /rGO under acidic conditions follows the adsorption evolution mechanism (AEM). Density functional theory (DFT) calculations further reveal the synergistic interaction between oxygen vacancies and the metal/oxide heterointerface. This interface-vacancy synergy not only facilitates the exposure of abundant active sites, but also promotes electron transfer from Pt to RuO 2 , thereby optimizing the kinetics of water dissociation. This work provides valuable insight into the rational design of bifunctional electrocatalysts for high-efficiency acidic water electrolysis and highlights the potential of 3D heterostructured materials for future PEMWE systems.