Plasmonic Copper-activated ZnO Microarrays for Efficient Photoelectrocatalytic Applications

In the present work, green synthesized plasmonic copper nanostructures derived from carbon quantum dots (PCQDs) activated ZnO microarrays (MAs) based catalyst system is developed and studied for photocatalytic activity and photoelectrocatalytic water splitting. CQDs are synthesized from pharmaceutical waste and used as a reducing agent to synthesize PCQDs of an average size of 10±2 nm. PCQDs decorated ZnO (PCQDs/ZnO) MAs exhibited enhanced photocurrent density of ∼7.1 mA/cm² at 1.23 V (vs. RHE), which is ∼11 fold to ZnO MAs alone (0.65 mA/cm² ). The catalyst exhibits an ABPE of 1.07% at 0.7 V (vs. RHE), IPEC of 8.8% for 450 nm, and hydrogen production rate of 435 μmol/h. The enhanced PEC characteristics are assigned to the improved photons collection and better charge transfer for their participation in oxidation/reduction reaction. The same is well supported with DFT studies for the PCQDs/ZnO MAs catalyst for the first time.