Tuning the surface properties of CuO films using the precursor aging approach for enhanced photoelectrocatalytic reactions

Abstract

The surface properties of semiconductors have a significant influence on their photoelectrocatalytic efficiency. This research presents a precursor aging method for tuning the surface properties of CuO films, for enhanced catalytic response. A precursor solution made using copper acetate, polyethylene glycol (PEG) 400, and diethanolamine, and aged for 1, 40, 80, 120, 150, 180, and 250 days is used in each case to fabricate CuO photocathodes via the dip-coating method. The films fabricated using the 1-day-old precursor reveal compact and homogeneous nanoparticles. The films eventually get tuned to yield highly porous and rougher surfaces after aging the precursors for 180–250 days. The film's bandgap decreases by 9% after 180–250 days of precursor aging. Photocathodes prepared using the 180-day-old precursor produce the optimum photocurrent density of 1.6 mA cm−2 at 0.35 V versus reversible hydrogen electrode (RHE), representing a 196% increase relative to the films fabricated using the 1-day-old solution. They also produce an anodic onset potential shift of 260 mV. This improved photoelectrocatalytic response is due to the porous morphology of the films, which produces a larger surface area that enhances light absorption, increases active sites for catalytic reactions, and reduces charge transfer resistance at the photocathode-electrolyte interface.