Regulating orbital interaction to construct quasi-covalent bond networks in Pt intermetallic alloys for high-performance fuel cells

This is the authors' abstract. We don't add key points for this paper.

The long-standing challenges facing Pt-based alloy catalysts in oxygen reduction reactions (ORRs) are rapid oxidation and loss of transition metal/Pt in proton exchange membrane fuel cells (PEMFCs). In this work, we report a concept of “covalentization” in intermetallic L10-PtMM’ (M = Fe, Co, Ni and M’ = one of the 4th-period elements (from Ti to Ge)) alloys to enhance their electrochemical stability. Specifically, the formation of a quasi-covalent bond network in L10-PtMM’ due to the less occupied antibonding states induced by high d-band positions of M’ elements (e.g., Ti, V, Cr) enhances atomic bond order and strength, diminishing Co anodic dissolution via strengthened Pt/Co-M’ bonds and reducing Co cathodic corrosion by inhibiting Pt oxidation through an electron buffering effect. The developed L10-PtCoCr/C catalysts show a high mass activity (MA = 1.27 A mgPt−1) and rated power (16.5 W mgPt−1) in PEMFCs at a low total Pt loading of 0.075 mgPt cm−2. The catalysts also exhibit high electrochemical stability with ~3% and 5% loss of MA and rated power after 30,000 accelerated durability testing cycles and projects a lifetime of about 42,000 hours. Pt-based alloy cathode catalysts in proton exchange membrane fuel cells face persistent challenges, including rapid oxidation and loss of transition metal/Pt. Here, the authors report a covalentization concept in intermetallic L10-structure Pt-based alloys to boost stability in fuel cells.