Single nanostructured gold amalgam microelectrode electrochemiluminescence: From arrays to a single point

• Published in: Sensors and actuators. B, Chemical Vol. 286; pp. 282 - 288
• Main Authors: Podešva, Pavel, Liu, Xiaocheng, Neužil, Pavel
• Format: Journal Article
• Language: English
• Published: Lausanne Elsevier B.V 01.05.2019; Elsevier Science Ltd
• Subjects: Array of microelectrodes; Arrays; Cobalt; Dealloying; Deoxyribonucleic acid; DNA; Electrochemical cells; Electrochemiluminescence; Electrodes; Embedded systems; Gold; Gold amalgam; Hydrogen evolution; Lithography; Material properties; Microelectrodes; Microfluidics; Nanostructure; Noble metals; Platinum; Proteins; Reaction kinetics; Single-spot observation; Electrochemiluminescence; Array of microelectrodes; Gold amalgam; Dealloying; Single-spot observation
• ISSN: 0925-4005; 1873-3077
• DOI: 10.1016/j.snb.2018.11.127

[Display omitted] •A technique to prepare an array of Au nanostructured electrodes by selective co-deposition of AuxHgy.•Subsequent electrochemical dealloying of Hg resulting in branched microstructures with Hg free surface.•The surface area was ≈824×greater with respect to the original area defined by lithography.•Electrochemoluminescence reaction using the Ru(bpy)32+ based system. The use of microelectrodes or arrays of microelectrodes is beneficial for electrochemical systems with minute volumes such as sensors embedded in microfluidics. Here, we present an approach to fabricate nanostructured gold amalgam (AuxHgy) via a single-step co-deposition method. The gold amalgam was selectively deposited through a lithography mask with opening areas of diameter 4 μm, forming an array of microelectrodes with a nanostructured surface. This surface was three orders of magnitude larger than that defined by lithography. The surface material properties were modified by the subsequent removal of Hg using a dealloying method in order to enable operation in the positive potential region similar to conventional Au electrodes. We performed electrochemiluminescence (ECL) with an entire array in an electrochemical cell and observed the ECL from a single microelectrode to study details of the ECL reactions and their kinetics. The nanostructured AuxHgy microelectrodes have overvoltage to hydrogen evolution, thus allowing the electrodes to operate in more negative potentials compared with noble metals such as Au and Pt, resulting in an ultrasensitive detection of materials such as DNA and proteins.