Regulating orbital interaction to construct quasi-covalent bond networks in Pt intermetallic alloys for high-performance fuel cells.
basic_science · Level V
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- Record sourced from PubMed, PMID 40425568.
- Also identified by DOI 10.1038/s41467-025-60171-z and PMC identifier 12116772.
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Abstract
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 L1<sub>0</sub>-PtMM' (M = Fe, Co, Ni and M' = one of the 4<sup>th</sup>-period elements (from Ti to Ge)) alloys to enhance their electrochemical stability. Specifically, the formation of a quasi-covalent bond network in L1<sub>0</sub>-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 L1<sub>0</sub>-PtCoCr/C catalysts show a high mass activity (MA = 1.27 A mg<sub>Pt</sub><sup>-1</sup>) and rated power (16.5 W mg<sub>Pt</sub><sup>-1</sup>) in PEMFCs at a low total Pt loading of 0.075 mg<sub>Pt</sub> cm<sup>-2</sup>. 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.