Transition from Core-Shell to Janus Segregation Pattern in AgPd Nanoalloy by Ni Doping for the Formate Oxidation

Abstract Developing the nanoalloys with well-designed chemical ordering and understanding the correlation between the chemical ordering and catalytic property remain a challenge, yet represent an effective strategy to improve the performance of the nanoalloys. Herein, three AgPd-based nanoalloys with different composition-segregation types, namely, alloy (mixed-Ag19Pd72Ni9), core-shell (core-shell-Ag40Pd60) and janus (janus-Ag20Pd60Ni20) atomic arrangements, are developed via a successive co-reduction method and used in the formate oxidation reaction (FOR). The janus-Ag20Pd60Ni20 nanoalloy exhibits an electrocatalytic activity of 1.31 A mgPd−1 and remarkable long-term stability, outperforming the commercial Pd/C catalysts. The FOR activity follows the order of janus-Ag20Pd60Ni20 > core-shell-Ag40Pd60 > mixed-Ag19Pd72Ni9 nanoalloys. After galvanic replacement and acid treatment, the obtained galvanic-Ag20Pd60Ni20 and acid-Ag20Pd60Ni20 nanoalloys demonstrate 2.31 and 1.44 times higher mass activity than the janus-Ag20Pd60Ni20 nanoalloy. The improvements in the activity and stability can be attributed to largely increased Pd active sites on the surface of AgPd-based nanoalloys with optimal chemical ordering.