Dual co-catalysts activated hematite nanorods with low turn-on potential and enhanced charge collection for efficient solar water oxidation.

Hematite ( α -Fe 2 O 3 ) photoanode suffers from significant photocarrier recombination and sluggish water oxidation kinetics for photoelectrochemical water splitting. To address these challenges, this work demonstrates the construction of dual co-catalysts modified Fe 2 O 3 nanorods photoanode by strategically incorporating CoPi and Co(OH) x for photoelectrochemical water oxidation. The Fe 2 O 3 /CoPi/Co(OH) x nanorods photoanode exhibits the lowest ever turn-on potential of 0.4 V RHE (versus reversible hydrogen electrode) and a photocurrent density of 0.55 mA cm -2 at 1.23 V RHE , 358% higher than that of pristine Fe 2 O 3 nanorods. The dual co-catalysts modification enhances the light-harvesting efficiency, surface photovoltage and hole transfer kinetics of the hybrid photoanode. The dual co-catalyst coupling also increases the carrier density and significantly reduces the depletion width (1.9 nm), resulting in improved conductivity and favorable band bending, boosting photogenerated hole transfer efficiency for water oxidation.