Shape Control of Monodispersed Sub-5 nm Pd Tetrahedrons and Laciniate Pd Nanourchins by Maneuvering the Dispersed State of Additives for Boosting ORR Performance
Zhang, HF (Zhang, Huaifang)[ 1 ] ; Qiu, XY (Qiu, Xiaoyu)[ 1 ]*（邱晓雨）; Chen, YF (Chen, Yifan)[ 1 ] ; Wang, SZ (Wang, Shangzhi)[ 1 ] ; Skrabalak, SE (Skrabalak, Sara E.)[ 2 ] ; Tang, YW (Tang, Yawen)[ 1 ]*（唐亚文）
[ 1 ] Nanjing Normal Univ, Sch Chem & Mat Sci, Jiangsu Collaborat Innovat Ctr Biomed Funct Mat, Jiangsu Key Lab New Power Batteries, Nanjing 210023, Jiangsu, Peoples R China
[ 2 ] Indiana Univ, Dept Chem, 800 E Kirkwood Ave, Bloomington, IN 47405 USA
It is a great challenge to simultaneously control the size, morphology, and facets of monodispersed Pd nanocrystals under a sub-5 nm regime. Meanwhile, quantitative understanding of the thermodynamic and kinetic parameters to maneuver the shape evolution of nanocrystals in a one-pot system still deserves investigation. Herein, a systematic study of the density functional theory (DFT)-calculated adsorption energy, thermodynamic factors, and reduction kinetics on Pd growth patterns is reported by combining theory and experiments, with a focus on the dispersed state of additives. As pure models, monodispersed Pd tetrahedrons enclosed by (111) facets with a narrow size distribution of 4.9 +/- 1 nm and a high purity approaching 98% can be obtained when using 1,1 '-binaphthalene (C20H14) +2NH(3) as additives. Specifically, laciniate Pd nanourchins (Pd LUs) can evolve via anisotropic growth when replacing additive with dose-consistent 1,1 '-binaphthyl-2,2 '-diamine (C20H16N2, two -NH2 binding in C20H14). Catalytic investigations show that the sub-5 nm Pd tetrahedrons exhibit higher activity in both the oxygen reduction (E-onset = 1.025 V, E-1/2 = 0.864 V) and formic acid oxidation reaction with respect to the Pd LUs and Pd black, which represents a great step for the development of well-defined Pd nanocrystals with size in the sub-5 nm regime as non-Pt electrocatalysts.