Biosensors and Bioelectronics 27 (2011) 160–166 Contents lists available at ScienceDirect Biosensors and Bioelectronics jou rn al h om epa ge: www.elsevier.com/locate/bios Nanoporous PtAg and PtCu alloys with hollow ligaments for enhanced electrocatalysis and glucose biosensing Caixia Xu a,∗ , Yunqing Liu a , Fa Su a , Aihua Liu b , Huajun Qiu b a School of Chemistry and Chemical Engineering, University of Jinan, Jinan, 250022, China b Laboratory for Nanobioelectronics & Biosensors, Qingdao Institute of Bioenergy and Bioprocess Technology, and Key Laboratory for Biofuels, Chinese Academy of Sciences, Qingdao 266101, China a r t i c l e i n f o Article history: Received 23 April 2011 Received in revised form 28 June 2011 Accepted 28 June 2011 Available online 7 July 2011 Keywords: Dealloying Galvanic replacement Electrocatalyst Hollow nanostructure Glucose biosensor a b s t r a c t Nanoporous silver (NPS) and copper (NPC) obtained by dealloying AgAl and CuAl alloys, respectively, were used as both three-dimensional templates and reducing agents for the fabrication of nanoporous PtAg (NPS-Pt) and PtCu (NPC-Pt) alloys with hollow ligaments by a simple galvanic replacement reaction with H 2 PtCl 6 . Electron microscopy and X-ray diffraction characterizations demonstrate that NPS and NPC with similar ligament sizes (30–50 nm) have different effects on the formed hollow nanostructures. For NPS-Pt, the shell of the hollow ligament is seamless. However, the shell of NPC-Pt is comprised of small pores and alloy nanoparticles with a size of ∼3 nm. The as-prepared NPS-Pt and NPC-Pt exhibit remarkably improved electrocatalytic activities towards the oxidation of ethanol and H 2 O 2 compared with state-of-the-art Pt/C catalyst, and can be used for sensitive electrochemical sensing applications. The hierarchical nanoporous structure also provides a good microenvironment for enzymes. After immobilization of glucose oxidase (GOx), the enzyme modified nanoporous electrode can sensitively detect glucose in a wide linear range (0.6–20 mM). © 2011 Elsevier B.V. All rights reserved. 1. Introduction Noble metal-based nanomaterials have continued to receive considerable interest due to their unique physicochemical proper- ties. They have been widely used in electroanalytical investigations and have enormous potentials for constructing electrochemical sensing platforms with high sensitivity to detect different target molecules. Pt-based nanomaterials have been extensively stud- ied due to its high electrocatalytic activity towards many small molecules such as ethanol, hydrogen peroxide, etc. (Chen and Holt- Hindle, 2010; Guo et al., 2010b). These Pt-based nanomaterials can also be further functionalized with biocatalyst (enzyme) and the formed Pt nanomaterial-enzyme hybrid can be used for wider electroanalytical applications by the combination of the electrocat- alytic activities of Pt nanomaterials and the biocatalytic activities of enzymes. For example, Pt nanoparticle-glucose oxidase hybrid has been used for glucose biosensing by electrochemical determi- nation of hydrogen peroxide produced by the enzymatic reaction (Chakraborty and Raj, 2009; Jena and Raj, 2011; Ji et al., 2011; Zou et al., 2008; Lee and Park, 2010; Tang et al., 2010). Thus, Pt-based nanomaterials with high electrocatalytic activities and large surface areas are very desirable for such biosensor fabrica- ∗ Corresponding author. E-mail addresses: chm xucx@ujn.edu.cn (C. Xu), qiuhuajun@gmail.com (H. Qiu). tion. Great efforts have been dedicated towards the construction of functional Pt nanostructures with various morphologies in order to achieve higher catalytic activity and better precious-metal utiliza- tion. However, pure Pt is easily poisoned by carbon monoxide (CO). It has been demonstrated that the addition of a second metal, such as Ru and Au, can often greatly improve both the overall catalytic activity and the tolerance to poisoning (Ryu et al., 2010; Safavi and Farjami, 2011; Xiao et al., 2009). These bimetallic nanostructures are usually in forms of alloys, core/shell structures, and heteroag- gregates (Chen et al., 2010; Deng et al., 2010). Hollow metallic nanostructures represent a class of interest- ing materials with high surface area, low density, and rich surface chemistry to allow function integration. The in situ galvanic replacement reaction has been proved to be an effective route for the fabrication of hollow alloy nanostructures. For example, using nanostructured Te, Cu, and Ag as substrates, Pt, Pd, or Au-based alloy nanomaterials have been successfully prepared (Chen et al., 2005; Guo et al., 2010a; Sun and Xia, 2004; Xu et al., 2009a,b). However, these substrate nanostructures are usually fabricated by surfactant-assisted wet-chemical processes with the excessive use of organic chemicals at relatively high temperatures. Recently, a simple corrosion method (also called dealloying) was demon- strated to be very powerful in generating three-dimensional (3D) bicontinuous nanoporous metal structures (Qiu et al., 2009b, 2011; Xu et al., 2007). Nanoporous metals prepared by dealloying have some advantages such as excellent electron conductivity, no par- 0956-5663/$ – see front matter © 2011 Elsevier B.V. All rights reserved. doi:10.1016/j.bios.2011.06.036