Display of Solid-State Materials Using Bipolar Electrochemistry

Abstract

We report the formation and characterization of one-dimensional chemical composition gradients of CdS on Au surfaces using bipolar electrodeposition. When an external electric field is applied across an electrically floating Au electrode immersed in a bipolar electrochemical cell, a position-dependent interfacial potential difference is generated along the length of the Au. This potential gradient can be used to induce variations of chemical composition within thin films electrodeposited onto the Au bipolar electrode (BPE). Thin films formed by bipolar electrodeposition represent continuous one-dimensional solid-state material libraries and were screened using resonance Raman microscopy and Auger electron spectroscopy. As predicted from simple thermodynamic considerations, we observed three distinct deposition zones scanning from the cathodic pole to the midpoint of the BPE: (i) CdS+Cd, (ii) stoichiometric CdS, and (iii) elemental S. Bipolar electrodeposition can be used to generate material libraries rapidly and without direct electrical contact to the substrate using extremely simple instrumentation.

Single‐Step Screening of the Potential Dependence of Metal Layer Morphologies along Bipolar Electrodes

“…Previously, BPE has been shown to be effective for designing surface gradients, as illustrated by the preparation of polymeric layers with doping gradients, or molecular gradients that can be probed by heterogeneous electron transfer . Recently, metal‐based gradients involving composition or roughness variation on planar bipolar surfaces have equally been described . In the present Communication, the straightforward, single‐step preparation of complex gradients exhibiting various metal morphologies on cylindrical bipolar electrodes is reported for the first time.…”

Measurements of Potential on and Current through Bipolar Electrode in U-Type Electrolytic Cell with a Shielding Wall

“…[7][8][9][10][11][12][13] In a microfluidic space with a thin conducting substrate, an electric field from a pair of external driving electrodes can induce the BPE to realize anodic and cathodic reactions at both sides. The BPE is driven by IR-drop in the electrolyte, so that a low concentration of electrolyte is favorable to induce BPE under low current (moderate) conditions.…”

Bipolar Electrochemical Approach with a Thin Layer of Supporting Electrolyte towards the Growth of Self‐Organizing TiO2 Nanotubes

“…In particular, as there is no direct voltage source connected to initiate the redox reactions, multiple bipolar electrodes (samples) can be controlled with just a single voltage source or even a battery . This wireless mechanism of bipolar electrochemistry makes it a promising tool for a large number of applications in areas of analytical chemistry, materials science, particle motion, and seawater desalination . Some crucial factors affecting pore diameter and morphology of TiO 2 NTs are electrolyte concentration, applied voltage, polarization time, and water content.…”