Nanostructured Cu2O Synthesized via Bipolar Electrochemistry.

Steven Mcwilliams,Ruri Agung Wahyuono,Connor D Flynn,Anna Ignaszak,Jennifer Mcwilliams,Markus Rettenmayr,Andreas Undisz,Donna C Arnold

doi:10.3390/nano9121781

Abstract

Cuprous oxide (Cu2O) was synthesized for the first time via an open bipolar electrochemistry (BPE) approach and characterized in parallel with the commercially available material. As compared to the reference, Cu2O formed through a BPE reaction demonstrated a decrease in particle size; an increase in photocurrent; more efficient light scavenging; and structure-correlated changes in the flat band potential and charge carrier concentration. More importantly, as-synthesized oxides were all phase-pure, defect-free, and had an average crystallite size of 20 nm. Ultimately, this study demonstrates the impact of reaction conditions (e.g., applied potential, reaction time) on structure, morphology, surface chemistry, and photo-electrochemical activity of semiconducting oxides, and at the same time, the ability to maintain a green synthetic protocol and potentially create a scalable product. In the proposed BPE synthesis, we introduced a common food supplement (potassium gluconate) as a reducing and complexing agent, and as an electrolyte, allowing us to replace the more harmful reactants that are conventionally used in Cu2O production. In addition, in the BPE process very corrosive reactants, such as hydroxides and metal precursors (required for synthesis of oxides), are generated in situ in stoichiometric quantity, providing an alternative methodology to generate various nanostructured materials in high yields under mild conditions.

Highlights

In recent years, cuprous oxide (Cu2O) has become increasingly popular as a semiconductor given its dual ability to convert solar energy and facilitate the photoelectrochemical splitting of water in photovoltaic devices [1,2]
The higher carrier concentration and flat band potential are related to smaller particle size
We demonstrate a wireless bipolar electrochemical synthesis of cuprous oxide, targeting the impact of reaction conditions on structure, morphology, surface chemistry, and photo-electrochemical activity

Summary

Introduction

Cuprous oxide (Cu2O) has become increasingly popular as a semiconductor given its dual ability to convert solar energy and facilitate the photoelectrochemical splitting of water in photovoltaic devices [1,2]. Numerous studies have been devoted to improving the stability of Cu2O electrodes in solution through surface modification with conducting polymers, metals, and oxides [5,6,7]. These protective layers inhibit photo-corrosion of Cu2O, and facilitate the band structure for improved charge transport [6]. Cu2O particles are labeled cleaning “nano-swimmers” or “micromotors” as they exhibit self-propelled movement, driven by gases that are generated at one end of the Cu2O particle With this Cu2O-based decontamination method, new cleaning suspensions represent a less toxic alternative when compared to conventional water purification methods that produce enormous quantities of secondary waste (e.g., chromium, iron compounds)

Methods

Results

Conclusion