Improved performance of photoelectrochemical water oxidation from nanostructured hematite photoanode with an immobilized molecular cobalt salophen catalyst

The development of molecule-semiconductor hybrid photoanodes is considered to possess the potential in fabricating practical photoelectrochemical (PEC) devices with high efficiency. Herein, α-Fe₂O₃ photoanode with morphology of highly interconnected and aligned nanorod arrays have been successfully grown on fluorine-doped tin oxide, and its PEC activity toward water oxidation was facilely optimized by controlling the electrodeposition time. And then, this photoanode was modified with a Co(II) salophen complex with pyrene moiety via a hydrophobic interaction to construct a hybrid photoanode. The obtained photoanode manifests remarkable enhanced PEC performance relative to pristine α-Fe₂O₃, affording a remarkable photocurrent response of 0.7 mA cm⁻² at 1.23 V versus reversible hydrogen electrode and a low catalytic onset potential of 0.93 V in a neutral aqueous solution under simulated sunlight illumination (100 mW cm⁻²). Furthermore, the durability test indicates that this hybrid photoanode possesses good stability and a Faradaic efficiency of nearly 100% for oxygen evolution. The superior PEC performance is mainly due to the synergistic contribution of the Co(II) salophen co-catalyst and the α-Fe₂O₃ nanorod arrays, in which the co-catalyst greatly suppresses the surface holes/electrons recombination and accelerates the surface oxygen evolution reaction kinetics.

One novel hybrid photoanode integrating α-Fe₂O₃ nanorod arrays semiconductor with Co(II) salophen co-catalyst is facilely fabricated and demonstrates remarkable photoelectrochemical performance toward water oxidation.