Ordered Mesoporous Intermetallic Ga‐Pt Nanoparticles: Phase‐Controlled Synthesis and Performance in Oxygen Reduction Electrocatalysis

Abstract The intermetallic phase control is a promising strategy to optimize the physicochemical properties of ordered intermetallic compounds and engineer their performance in various (electro)catalytic reactions. However, the intermetallic phase‐dependent catalytic performance is still rarely reported because of the difficulty in synthesizing ordered intermetallics with precisely controlled phase structures at atomic level, especially having ordered mesoscopic structure/morphology. Here, we successfully reported a precise synthesis of two phase‐pure mesoporous intermetallic gallium‐platinum ( meso ‐ i ‐Ga‐Pt) nanoparticles, including meso ‐ i ‐Ga 3 Pt 5 with an orthorhombic space group and meso ‐ i ‐Ga 1 Pt 1 with a non‐symmorphic chiral cubic space group. The intermetallic phase control of ordered meso ‐ i ‐Ga‐Pt nanoparticles was realized by carefully tuning the induced Ga salts with different anions that optimized the free energies during the synthesis. The intermetallic phase‐dependent catalytic performance of ordered meso ‐ i ‐Ga‐Pt was systematically evaluated for oxygen reduction reaction (ORR) electrocatalysis, with completely opposite catalytic performance in alkaline media. Interestingly, ordered meso ‐ i ‐Ga 1 Pt 1 catalyst with chiral atomic arrangements disclosed unexpected high ORR activity and stability with 5.9 and 3.2 enhancement factors in mass activity compared to those of meso ‐ i ‐Ga 3 Pt 5 and commercial Pt/C.