Chlorophyll/Cu2O Heterostructure Leads to Increased Applied Bias Photon-to-Current Efficiency toward Enhanced Water Splitting

Abstract

The ongoing climate change and global warming urge quick replacement of fossil fuels and demand innovative strategies for clean energy generation energy. The solar-induced photoelectrochemical water splitting mechanism holds immense potential for hydrogen generation through metal oxide photocatalysts. However, poor visible light absorption, aqueous instability, electrode degradation, and exciton recombination are major hurdles to its application. To address these challenges, we have employed p-type cuprous oxide (Cu₂O) electrodeposited on a conducting indium tin oxide (ITO) substrate to form a photoanode. The electrode was characterized systematically for its physicochemical and electrical properties. To facilitate solar to hydrogen conversion and enhance durability, we modified the electrode surface with chlorophyll. Owing to chlorophyll’s exceptional visible light absorption characteristics, the chlorophyll-modified Cu₂O electrode exhibited a remarkably high photocurrent density (3.26 mA/cm²) and energy conversion, yielding a 0.82% to 1.37% increase in the applied bias photon-to-current efficiency (ABPE %). Furthermore, density of states calculations validated the bonding interactions between Mg (chlorophyll) and O (Cu₂O) at the heterojunction. The electrode stabilities during the electrochemical reaction and post-electrochemical reaction were also compared, showing its potential applicability for hydrogen generation.