Boron Incorporation Induces Lattice Expansion in Platinum Nanoparticles for Enhanced Oxygen Reduction Reaction

The oxygen reduction reaction (ORR) is a key cathodic process in zinc-air batteries, while its sluggish kinetics and the limited stability of Pt nanoparticles constrain practical performance. Achieving high activity, selectivity, and stability while minimizing Pt loading remains a key objective in electrocatalyst design. Herein, B-doped Pt nanoparticles supported on carbon nanobowls (B-Pt/CNBs) with an estimated Pt:B:C atomic ratio of 1.00:0.86:98.14 were synthesized by an ice-bath reduction strategy. In alkaline media, B-Pt/CNBs deliver an onset potential of 1.073 V versus RHE and a half-wave potential of 0.966 V versus RHE, with an electron transfer number close to 4 and an H₂O₂ yield below 5%. The catalyst also shows enhanced methanol tolerance and durability, retaining 92.3% of its initial ECSA after 10 000 CV cycles. DFT free-energy calculations show that B doping decreases the uphill free-energy changes for the conversion of O* to OH* and OH* to H₂O, facilitating the protonation and removal of oxygen-containing intermediates. This work demonstrates B doping as an effective strategy for designing active and durable low-Pt ORR electrocatalysts.