Weixin Miao^a, Songliang Liu^a,*, Yuewen Sun^a, Cong Zhang^a, Meixiang Zheng^a, Guangshuo Li^a, Xuejing Cui^a, Xin Zhou^b,c,*, and Luhua Jiang^a,*

^a College of Materials Science and Engineering, Qingdao University of Science and Technology, Qingdao 266042, P. R. China

^b Interdisciplinary Research Center for Biology and Chemistry, Liaoning Normal University, Dalian 116029, P. R. China

^c College of Environment and Chemical Engineering, Dalian University, Dalian 116622, P. R. China

^* Corresponding authors: liusongliang@qust.edu.cn; zhouxin@dlu.edu.cn; luhuajiang@qust.edu.cn

Abstract:

Electrocatalysis, a form of heterogeneous catalysis, is closely associated with both catalyst properties and the catalysts/electrolyte interfacial microenvironment. Herein, we rationally design and synthesize a unique PdCu nano-sea urchins (PdCu NSUs) featured with high-curvature nanotips, by which the interfacial microenvironment is expected to be tailored to the electrocatalytic reactions. PdCu NSUs exhibits excellent activity for ethanol electrooxidation, with a specific activity of 4.11 mA cm⁻² and a mass activity of 2.24 mA μg_Pd⁻¹, and a high Faraday efficiency (FE) of 96.4% toward acetic acid. COMSOL finite element simulations confirm that the unique nanotips could induce a local electric field due to the accumulation of positive charges in the nanotips, resulting in enrichment of OH⁻ at the catalyst surface to promote the formation of Pd−OH_ads, a species required by ethanol dehydrogenation. Furthermore, DFT calculations and in-situ electrochemical Fourier transform infrared spectroscopy discover that the d-band center of Pd significantly downshifts in PdCu alloy, which facilitates the desorption of the produced acetic acid. This work provides a new electrocatalytic material with high-curvature nanotips, and also clarifies how the material morphology, by inducing local electric fields, affects the interfacial microenvironment and thus the catalytic activity and selectivity.

Keywords: PdCu nano-sea urchins; nanotips; electrocatalyst; local electric field; ethanol oxidation reaction