Defective TiO2 composite photoanodes with surface-modified Prussian blue for efficient photoelectrochemical water splitting†

Solar hydrogen production has garnered significant attention in addressing the energy crisis due to its efficient and environmentally friendly nature. In this study, we successfully used a simple electrochemical reduction method to introduce oxygen vacancies on a TiO₂ nanorod photoanode, termed defective TiO₂ (D-TiO₂). Meanwhile, Prussian blue (PB) was deposited on D-TiO₂ to create a core–shell composite photoanode material. By optimizing the reduction time, the charge separation of D-TiO₂ is improved. The addition of PB resulted in the formation of a II-type heterojunction between TiO₂ and PB. The formation of the heterojunction enlarges the light absorption range of TiO₂, increases the active sites, and reduces the recombination of photogenerated charges due to the large surface area of PB. The photocurrent density of D-TiO₂@PB reaches 2.10 mA cm⁻² at 1.23 V vs. RHE, with an enhanced IPCE of 35.8%.