Sub-10-nm-sized Au@Au x Ir1-x metal-core/alloy-shell nanoparticles as highly durable catalysts for acidic water splitting

Huimin Wang; Zhe-Ning Chen; Yuanyuan Wang; Dongshuang Wu; Minna Cao; Fanfei Sun; Rong Cao

doi:10.1093/nsr/nwae056

Sub-10-nm-sized Au@Au _x Ir_1-_x metal-core/alloy-shell nanoparticles as highly durable catalysts for acidic water splitting

Natl Sci Rev. 2024 Feb 7;11(4):nwae056. doi: 10.1093/nsr/nwae056. eCollection 2024 Apr.

Authors

Huimin Wang^{1

2}, Zhe-Ning Chen¹, Yuanyuan Wang³, Dongshuang Wu³, Minna Cao^{1

2}, Fanfei Sun⁴, Rong Cao^{1

2

5}

Affiliations

¹ State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou 350002, China.
² University of Chinese Academy of Sciences, Beijing 100049, China.
³ School of Materials Science and Engineering, Nanyang Technological University, Singapore 639798, Singapore.
⁴ Shanghai Synchrotron Radiation Facility, Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201204, China.
⁵ Fujian Science & Technology Innovation Laboratory for Optoelectronic Information of China, Fuzhou 350108, China.

Abstract

The absence of efficient and durable catalysts for oxygen evolution reaction (OER) is the main obstacle to hydrogen production through water splitting in an acidic electrolyte. Here, we report a controllable synthesis method of surface IrO_x with changing Au/Ir compositions by constructing a range of sub-10-nm-sized core-shell nanocatalysts composed of an Au core and Au_xIr_1-_x alloy shell. In particular, Au@Au_0.43Ir_0.57 exhibits 4.5 times higher intrinsic OER activity than that of the commercial Ir/C. Synchrotron X-ray-based spectroscopies, electron microscopy and density functional theory calculations revealed a balanced binding of reaction intermediates with enhanced activity. The water-splitting cell using a load of 0.02 mg_Ir/cm² of Au@Au_0.43Ir_0.57 as both anode and cathode can reach 10 mA/cm² at 1.52 V and maintain activity for at least 194 h, which is better than the cell using the commercial couple Ir/C‖Pt/C (1.63 V, 0.2 h).

Keywords: acidic water splitting; catalytic stability; controllable synthesis of surface IrOx; oxygen evolution reaction; transition metal catalysts.