The mercury electrode is an attractive material for a working electrode due to its atomically smooth, self-healing surface and large potential window. Amalgams are attractive substitutes for toxic Hg in various electrochemical applications. They are typically prepared by mixing different metals with Hg, or by electrodeposition of Hg on the metals’ surfaces. These methods offer little to no control of the amalgam compositions and morphology, which is a major disadvantage of their usage. Here, we show a highly controllable method used to fabricate an array of nanostructured Au amalgam electrodes in a single step, with tailored sensitivity and composition. This method is based on the direct electrochemical co-deposition of Au and Hg from their cyano complexes, which results in branched AuxHgy structures with controlled ratios between both metals. We investigated the effects of solution composition and deposition potential on the electroactive surface area, its morphology, and the electrode potential window. The nanostructured amalgam could replace the Hg electrode for heavy metal detection with high sensitivity, due to its enhanced area and potential window similar to that of Hg. This method of in situ wet-chemistry fabrication of the Hg/Au amalgam, with tailorable nanostructure and composition, opens the door to a renaissance of Hg-based electrodes.
Bibliographical noteFunding Information:
Pavel Podešva, Xiaocheng Liu, and Pavel Neužil would like to acknowledge financial support from the G2016QR0001 in China, as well as the help of technicians from a cleanroom at Northwestern Polytechnical University, Xi’an, P.R. China with the fabrication of the chips used in this work. The authors would also like to acknowledge assistance with microfabrication by the cleanroom staff of Micro/Nanotechnology Research Center, of the State Key Laboratory for Manufacturing Systems Engineering of Xi’an Jiaotong University, and the staff of the SEM imaging facility at the Shaanxi Institute of Geology and Mineral Resources Experiment for the SEM images and EDS study. This work was also partially supported by CEITEC Nano+project (CZ.02.1.01/0.0/0.0/16_13/0001728). M.P. acknowledges the financial support of Grant Agency of the Czech Republic (EXPRO: 19-26896X ).
All Science Journal Classification (ASJC) codes
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics
- Surfaces, Coatings and Films
- Metals and Alloys
- Electrical and Electronic Engineering
- Materials Chemistry