Electrochemically Derived Crystalline CuO from Covellite CuS Nanoplates: A Multifunctional Anode Material

Area of Science:

• Electrochemistry and Materials Science

Background:

• Electrochemical water splitting is crucial for sustainable energy, but requires efficient, durable, and cost-effective catalysts.
• Understanding surface active species under electrochemical conditions is vital for catalyst development.

Purpose of the Study:

• To synthesize covellite phase copper sulfide (CuS) nanoplates using a facile hydrothermal method.
• To investigate the electrochemical properties of CuS as a precatalyst for alkaline water oxidation.
• To characterize the electrochemically activated CuO/Cu(OH)2 heterostructure for oxygen evolution reaction (OER) and overall water splitting.

Main Methods:

• Hydrothermal synthesis of covellite CuS nanoplates.
• Electrochemical characterization including cyclic voltammetry, chronoamperometry, and Tafel analysis on glassy carbon and nickel foam (NF) electrodes.
• Spectroscopic and microscopic analysis (X-ray photoelectron spectroscopy, Raman spectroscopy) for material characterization before and after electrochemical activation.

Main Results:

• Covellite CuS was synthesized and characterized, showing mixed-valent copper states (Cu(I)/Cu(II)).
• Electrochemical activation transformed CuS into a CuO/Cu(OH)2 heterostructure (CuS_EA), exhibiting superior OER activity with a low overpotential (349 mV at 20 mA cm-2).
• The CuS_EA/NF anode demonstrated remarkable stability, maintaining current density over 10 hours and enabling efficient water electrolysis and feedstock oxidation.

Conclusions:

• The *in situ* constructed CuO/Cu(OH)2 heterostructure from covellite CuS is a highly active and stable electrocatalyst for OER and overall water splitting.
• This catalyst system shows significant potential for both clean energy generation and the electrochemical transformation of industrial organic feedstocks.
• The study highlights a promising pathway for developing advanced copper-based catalysts for sustainable energy applications.