Contents lists available at ScienceDirect Intermetallics journal homepage: www.elsevier.com/locate/intermet Nanoporous copper fabricated from Zr 65 Cu 17.5 Fe 10 Al 7.5 amorphous alloy and its electrocatalytic oxidation performance Min Zhou a , Xiang Huang a , Kiros Hagos b,c , Yuwen Cui a , Liqun Ma a,d,* a School of Materials Science and Engineering, Nanjing Tech University, Nanjing 210009, China b State Key Laboratory of Materials-Oriented Chemical Engineering, Nanjing Tech University, Nanjing 210009, China c Mizan-Tepi University, Mizan-Aman 260, Ethiopia d Jiangsu National Synergetic Innovation Center for Advanced Materials (SICAM), Nanjing Tech University, Nanjing 210009, China ARTICLE INFO Keywords: A. Amorphous metals Porous materials B. Corrosion F. Electrochemical characterization G. Catalysis ABSTRACT A series of bi-continuous and uniform nanoporous structures were fabricated successfully through chemical dealloying from quaternary Zr 65 Cu 17.5 Fe 10 Al 7.5 amorphous ribbons in hydrofluoric acid (HF) solutions under a free corrosion condition. Nanoporous structures obtained from dealloying amorphous ribbons for 5 h in 0.02 M,0.035 M and 0.05 M HF solutions have mean pore sizes of 30–40 nm. A three-dimensional bi-continuous nanoporous copper (NPC) structure formed on Zr 65 Cu 17.5 Fe 10 Al 7.5 ribbon alloys has pore sizes of 44.91 nm,52.60 nm and 57.37 nm, respectively, after immersion in 0.02 M HF solution for 15 h, 20 h, and 25 h. It shows that the pore size of NPC structure increases with increasing the dealloying time. The cyclic voltam- metry (CV) results reveal that all NPC structures have the obvious electrocatalytic ability to the oxidation of (CH 2 OH) 2 solution, compared with the initial amorphous ribbon without oxidation peak on CV curve. Zr-Cu-Fe- Al amorphous alloys can be new candidates for fabricating NPC structures. 1. Introduction Nanoporous metals, as novel functional materials, which possess advantages of both nanomaterials and metallic materials, have great potential in applications of catalysis, sensors, optics, super-capacitors, energy storage, etc. [1–6]. Xingyou Lang et al. [7] reported that hybrid structures composed of nanoporous gold and nanocrystalline MnO 2 have improved conductivity, making them promising candidates as electrodes in supercapacitors. Due to the ultrahigh sensitivities at a low potential, nanoporous gold supported cobalt oxide microelectrodes [8] can be used for high-performance electrochemical biosensors. Nano- porous (Pt 1-x Fe x ) 3 Al/Pt displays excellent durability in long-term elec- trochemical cycling, with much higher specific and mass activities than those of commercially available Pt/C oxygen reduction reaction cata- lyst, which enable it a promising candidate as a cathode catalyst in PEM fuel cells or metal-air batteries [9]. Dealloying has been proved to be an effective and easy method to produce nanoporous materials by selective dissolution of less noble elements within the alloy, while the remaining elements can form nanoporous structures with bi-continuous ligaments by means of diffusion and redistribution [10–12]. A series of nanoporous noble metals, including Au [13,14], Pt [4,15], Pd [16,17], Ag [4,18], etc., have been fabricated successfully by chemical or electrochemical dealloying processes. However, the high expense of these nanoporous noble metals has restricted their ex- tensively commercial applications. In recent years, NPC has been at- tracted increasing attention due to its low cost [5]. Both crystalline and amorphous alloys can be used as precursors to produce nanoporous copper (NPC) by dealloying processes. Due to the absence of defects and heterogeneous microstructures, i.e. grain boundaries, second phases, element segregation, etc., amorphous alloys are expected to be better than crystalline alloys to be used as precursors to produce uniform nanoporous structure [19,20]. Tomohiro Aburada et al. [10] in- vestigated the dealloying behavior of Al-Cu-Mg based amorphous alloys in 1 M HCl solution and succeeded in fabricating NPC structure with a pore size of 10–30 nm. As reported by the group of Zhenhua Dan et al. [11,21–23], NPC structures with different pore sizes were successfully fabricated from Ti-Cu, Ti-Cu-Ag, and Mg-Cu-Y amorphous alloys. In addition, Zhifeng Wang et al. [5] studied the chemical dealloying be- havior of the Cu 52.5 Hf 40 Al 7.5 amorphous alloy in 0.5 M HF solution. In order to obtain a dealloyed product with good bendability, an amor- phous alloy containing interlayer with a certain thickness was suc- cessfully fabricated in the NPC ribbon. Zr-based amorphous alloys [24–28] have been attracted much interest because they possess high glass-forming ability (GFA), excellent corrosion resistance, unique http://dx.doi.org/10.1016/j.intermet.2017.06.005 Received 17 March 2017; Received in revised form 12 June 2017; Accepted 12 June 2017 * Corresponding author. School of Materials Science and Engineering, Nanjing Tech University, Nanjing 210009, China. E-mail address: maliqun@njtech.edu.cn (L. Ma). Intermetallics 90 (2017) 23–29 Available online 23 June 2017 0966-9795/ © 2017 Elsevier Ltd. All rights reserved. MARK