title: Pt skin on Pd-Co-Zn/C ternary nanoparticles with enhanced Pt efficiency toward ORR.
abstract: Exploring highly active, stable and relatively low-cost nanomaterials for the oxygen reduction reaction (ORR) is of vital importance for the commercialization of proton exchange membrane fuel cells (PEMFCs). Herein, a highly active, durable, carbon supported, and monolayer Pt coated Pd-Co-Zn nanoparticle is synthesized via a simple impregnation-reduction method, followed by spontaneous displacement of Pt. By tuning the atomic ratios, we obtain the composition-activity volcano curve for the Pd-Co-Zn nanoparticles and determined that Pd : Co : Zn = 8 : 1 : 1 is the optimal composition. Compared with pure Pd/C, the Pd8CoZn/C nanoparticles show a substantial enhancement in both the catalytic activity and the durability toward the ORR. Moreover, the durability and activity are further enhanced by forming a Pt skin on Pd8CoZn/C nanocatalysts. Interestingly, after 10 000 potential cycles in N2-saturated 0.1 M HClO4 solution, Pd8CoZn@Pt/C shows improved mass activity (2.62 A mg(-1)Pt) and specific activity (4.76 A m(-2)total), which are about 1.4 and 4.4 times higher than the initial values, and 37.4 and 5.5 times higher than those of Pt/C catalysts, respectively. After accelerated stability testing in O2-saturated 0.1 M HClO4 solution for 30 000 potential cycles, the half-wave potential negatively shifts about 6 mV. The results show that the Pt skin plays an important role in enhancing the activity as well as preventing degradation.
authors.affiliation: Key laboratory of Material Chemistry for Energy Conversion and Storage (Huazhong University of Science and Technology), Ministry of Education, Hubei Key Laboratory of Material Chemistry and Service Failure, School of Chemistry and Chemical Engineering, Huazhong University of Science and Technology, Wuhan, 430074, P.R. China. wangdl81125@hust.edu.cn.
authors.forename: Weiping
authors.initials: W
authors.lastname: Xiao
authors.forename: Jing
authors.initials: J
authors.lastname: Zhu
authors.forename: Lili
authors.initials: L
authors.lastname: Han
authors.forename: Sufen
authors.initials: S
authors.lastname: Liu
authors.forename: Jie
authors.initials: J
authors.lastname: Wang
authors.forename: Zexing
authors.initials: Z
authors.lastname: Wu
authors.forename: Wen
authors.initials: W
authors.lastname: Lei
authors.forename: Cuijuan
authors.initials: C
authors.lastname: Xuan
authors.forename: Huolin L
authors.initials: HL
authors.lastname: Xin
authors.forename: Deli
authors.initials: D
authors.lastname: Wang