Tantalum and aluminum co-doped iron oxide as a robust photocatalyst for water oxidation

Efficient and stable photocatalysts for water oxidation are highly sought after in the field of photoelectrochemical (PEC) water splitting. Herein, a new type of tantalum and aluminum co-doped iron oxide (Ta/Al-Fe2O3) material was fabricated by a simple drop coating method. XPS analysis suggests that Ta and Al were successfully co-doped into Fe2O3 and Ta can greatly influence the chemical environment of Al and O on the surface of catalyst. The resultant optimum (0.25%)Ta/(10%)Al-Fe2O3 film presented excellent enhanced PEC activity and photostability. A 15 times higher photocurrent density as well as two times higher incident-photon-to-current efficiency (IPCE, 430 nm) can be clearly observed relative to (10%)Al-Fe2O3 at 0.35 V vs. Ag/AgCl. The dramatic enhanced PEC and IPCE performance are attributed to mixed effects induced by tantalum doping, such as positive shift of flat band potential (ca. 50 mV), a reduction in anodic overpotential for water oxidation and greatly reduced charge transfer resistance, which eventually facilitate more efficient separation and easier transfer of photogenerated electron–hole pairs. The highly improved visible light activity and film stability indicate that tantalum and aluminum co-doped iron oxide will be a promising semiconductor for water oxidation.