Oxygen reduction reaction on Pt-based electrocatalysts: Four-electron vs. two-electron pathway

Oxygen reduction reaction (ORR) has attracted extensive attention as an important component for sustainable energy storage and conversion technologies. However, the sluggish kinetics has hampered the practical application. Pt-based nanomaterials have triggered much interest as the most promising electrocatalyst to facilitate the kinetics of ORR. Nonetheless, a major challenge for Pt-based electrocatalysts is to precisely control the selectivity of reaction pathways and possible products (H2O or H2O2) with a reduced loading amount of precious Pt. This review systematically summarizes the strategies to regulate the ORR performances of Pt-based electrocatalysts by accommodating the adsorption energy and spatial structure. Further discussion is implemented about the key factors to accelerate the kinetics of ORR and control the 4e-ORR and 2e-ORR pathways. Finally, we demonstrate the challenges and perspectives for further development of novel Pt-based electrocatalysts.