Femtosecond-Laser Synthesized PtBi Nanoalloys for Efficient Methanol Oxidation in Hybrid Electrolysis.

Hydrogen production through electrochemical seawater splitting is challenged by the energy-intensive oxygen evolution reaction and the competing chlorine evolution reaction. To overcome these obstacles, ligand-free platinum bismuth (PtBi) alloy nanoparticles (≈2 nm) are synthesized via femtosecond laser liquid ablation under nonequilibrium conditions, yielding metastable structures with tunable elemental compositions populated with defects. The Pt4Bi/C catalyst excels in alkaline methanol oxidation reaction (MOR), delivering a mass activity of 17.7 A mg-1 pt (11.5 times higher than 20% Pt/C) and a specific activity of 54.9 mA cm-2. In-situ Fourier transform infrared spectroscopy and ambient pressure X-ray photoelectron spectroscopy reveal a CO-free pathway enabled by Bi, reducing catalyst poisoning. Density functional theory calculations show that PtBi─O lowers d-band center of Pt, weakening the adsorption of *CO, promoting the adsorption of *OH, and lowering the energy barrier from *CHO to *HCOOH. As an example, a hybrid MOR-hydrogen evolution reaction (HER) electrolyzer demonstrates reduced voltage, suppresses side reactions, improves catalyst durability, achieves 545 mV at 10 mA cm-2, and maintains stability for 54 h below 1.1 V in natural seawater. This study demonstrates the efficacy of PtBi nanoalloys in efficient MOR catalysis for hybrid electrolysis systems toward sustainable hydrogen production.