Closed Bipolar Electrochemistry for the Low-Potential Asymmetrical Functionalization of Micro- and Nanowires

We demonstrate the application of closed bipolar electrochemistry for the asymmetrical deposition of metals and metal oxides on bipolar electrodes of decreasing dimensions, down to the nanoscale. We focus on the asymmetrical deposition of semiconducting oxides (TiO2, Cu2O, or Co2O3) and Pt on glassy carbon disks, carbon microwires, and gold nanowires. The optimization of the process is studied by using a four-electrode voltammetric cell. Scanning electron microscopies and energy-dispersive X-ray spectroscopy confirm the achievement of the desired deposition. Electron backscatter diffraction identifies cuprite in all of the Cu2O deposits. Closed bipolar electrochemistry allows the bipolar functionalization of carbon materials and gold nanowires by using electrolytes that are unsuitable for open bipolar electrochemistry, applying a potential difference as low as 1V. For the first time, Janus like nanosized objects are obtained by closed bipolar electrochemistry.