Regulation of Ferroelectric Polarization to Achieve Efficient Charge Separation and Transfer in Particulate RuO2/BiFeO3 for High Photocatalytic Water Oxidation Activity

Exploiting spontaneous polarization of ferroelectric materials to achieve high charge separation efficiency is an intriguing but challenging research topic in solar energy conversion. This work shows that loading high work function RuO2 cocatalyst on BiFeO3 (BFO) nanoparticles enhances the intrinsic ferroelectric polarization by efficient screening of charges to RuO2 via RuO2/BFO heterojunction. This leads to enhancement of the surface photovoltage of RuO2/BFO single nanoparticles nearly 3 times, the driving force for charge separation and transfer in photocatalytic reactions. Consequently, efficient photocatalytic water oxidation is achieved with quantum efficiency as high as 5.36 % at 560 nm, the highest activity reported so far for ferroelectric materials. This work demonstrates that, unlike low photocurrent density in film‐based ferroelectric devices, high photocatalytic activity could be achieved by regulating the ferroelectric spontaneous polarization using appropriate cocatalyst to enhance driving force for efficient separation and transfer of photogenerated charges in particulate ferroelectric semiconductor materials. The regulation of ferroelectric polarization by the interfacial built‐in electric field at RuO2/BFO Schottky‐like heterojunction provides high driving force for separation and transfer of photogenerated charges that leads to high visible light photocatalytic water oxidation activity. The cocatalyst plays a crucial role in exploiting the spontaneous polarization in particulate ferroelectric semiconductor photocatalysts to achieve high charge separation efficiency.