Efficient and durable water splitting in acidic media

Engineered for precise control of the active sites on Au@AuxIr1−x core-shell surface for efficient and durable water splitting in acidic media
(a) Valence band photoemission spectra of Au@AuxIr1-x and standard samples. The white bar represents the d-band center. (b) DFT calculated PDOS of d-bands and d-band centers for Au-Ir systems. (c) Structure-activity relationships. Credit: Science China Press

Recent research published in National Science Review by a team led by Dr. Rong Cao and Dr. Minna Cao from the Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, and Dr. Dongshuang Wu from Nanyang Technological University, Singapore, has demonstrated the successful design and synthesis of a series of sub-10 nm core-shell nanocatalysts consisting of an Au core and an AuxIr1-x alloy shell.

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The first author Dr. Huimin Wang successfully synthesized and systematically tested the electrocatalytic water-splitting performance of this series of materials.

Dr. Huimin Wang found that the active site IrOx can be precisely designed by modulating the Au/Ir component on the surface of the Au@AuxIr1-x core-shell structure. IrOx species on the Au@AuxIr1-x surface is generally considered the active species for OER.

However, an excessive amount of IrOx shifts the d-band center of the catalyst close to the Fermi level, causing a too-strong binding affinity of intermediates that needs a quite high overpotential for the OER. Synchrotron X-ray-based spectroscopies, electron microscopy, and density functional theory calculations combined with electrochemical tests revealed that an optimal ratio of IrOx combined with a suitable d-band center yields the best OER activity.

Among them, the intrinsic activity and durability of Au@Au0.43Ir0.57 are substantially improved. With a load of only 0.02 mgIr/cm2, it is stable for at least 320 h at a high current density of 100 mA/cm2.

Engineered for precise control of the active sites on Au@AuxIr1−x core-shell surface for efficient and durable water splitting in acidic media
Surface active and durable IrOx is precisely controlled by tuning Au/Ir compositions, which can realize a balance for activity and stability for water splitting. Credit: Huimin Wang.

More information:
Huimin Wang et al, Sub-10-nm-sized Au@AuxIr1−x metal-core/alloy-shell nanoparticles as highly durable catalysts for acidic water splitting, National Science Review (2024). DOI: 10.1093/nsr/nwae056

Provided by
Science China Press

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