Plasmonic Copper-activated ZnO Microarrays for Efficient Photoelectrocatalytic Applications

Area of Science:

• Materials Science
• Nanotechnology
• Renewable Energy

Background:

• Developing efficient catalysts for water splitting is crucial for sustainable hydrogen production.
• ZnO microarrays (MAs) show promise but require enhancement for improved photocatalytic activity.
• Carbon quantum dots (CQDs) offer tunable electronic properties for catalyst development.

Purpose of the Study:

• To develop and investigate a novel catalyst system using green synthesized plasmonic copper nanostructures derived from carbon quantum dots (PCQDs) integrated with ZnO microarrays (MAs).
• To evaluate the photocatalytic and photoelectrocatalytic water splitting performance of the developed PCQDs/ZnO MAs catalyst.
• To elucidate the underlying mechanisms responsible for the enhanced performance using theoretical studies.

Main Methods:

• Green synthesis of PCQDs from pharmaceutical waste, using CQDs as a reducing agent.
• Decoration of ZnO MAs with synthesized PCQDs to form the PCQDs/ZnO MAs catalyst.
• Characterization of photocatalytic and photoelectrocatalytic water splitting using techniques like photocurrent density measurements, ABPE, and IPEC.
• Theoretical investigation using DFT studies to understand charge transfer dynamics.

Main Results:

• PCQDs/ZnO MAs exhibited a significantly enhanced photocurrent density of ~7.1 mA/cm² at 1.23 V (vs. RHE), an ~11-fold increase compared to bare ZnO MAs.
• The catalyst demonstrated an applied bias photon-to-current efficiency (ABPE) of 1.07% at 0.7 V (vs. RHE) and an incident photon-to-current efficiency (IPEC) of 8.8% at 450 nm.
• A high hydrogen production rate of 435 μmol/h was achieved, indicating efficient water splitting.
• DFT studies provided insights into improved photon collection and charge transfer, supporting the enhanced PEC characteristics.

Conclusions:

• The developed PCQDs/ZnO MAs catalyst system offers a highly efficient and green approach for photocatalytic and photoelectrocatalytic water splitting.
• The integration of PCQDs with ZnO MAs significantly enhances charge separation and transfer, leading to superior hydrogen production.
• This work presents a novel, cost-effective, and sustainable method for renewable hydrogen fuel generation.