This study reports the design and synthesis of a spatially differentiated (SD) two-dimensional Bi4Ti3O12 (BTO) nanosheet structure to enhance the photocatalytic overall water splitting (OWS) efficiency. The SD structure overcomes the limitations of charge transfer across different crystal planes in a single crystal semiconductor, leading to effective charge redistribution within a crystal plane. The experimental results show that the resulting photocatalyst produces 40.3 μmol h-1 of hydrogen and 20.1 μmol h-1 of oxygen at a near stoichiometric ratio of 2:1 and a solar-to-hydrogen efficiency of 0.1% under simulated solar light. The charge distribution and lifetime dynamics are investigated using surface photovoltage microscopy (SPVM) and time-resolved photoluminescence (TRPL), respectively. The photocatalytic performance is further optimized by depositing Rh-CrOx and CoOx cocatalysts, which promote hydrogen production and oxygen evolution, respectively. The study demonstrates that the spatially differentiated BTO photocatalyst can achieve a significant improvement in OWS efficiency compared to pristine single-crystal BTO, making it a promising candidate for practical solar energy conversion applications.This study reports the design and synthesis of a spatially differentiated (SD) two-dimensional Bi4Ti3O12 (BTO) nanosheet structure to enhance the photocatalytic overall water splitting (OWS) efficiency. The SD structure overcomes the limitations of charge transfer across different crystal planes in a single crystal semiconductor, leading to effective charge redistribution within a crystal plane. The experimental results show that the resulting photocatalyst produces 40.3 μmol h-1 of hydrogen and 20.1 μmol h-1 of oxygen at a near stoichiometric ratio of 2:1 and a solar-to-hydrogen efficiency of 0.1% under simulated solar light. The charge distribution and lifetime dynamics are investigated using surface photovoltage microscopy (SPVM) and time-resolved photoluminescence (TRPL), respectively. The photocatalytic performance is further optimized by depositing Rh-CrOx and CoOx cocatalysts, which promote hydrogen production and oxygen evolution, respectively. The study demonstrates that the spatially differentiated BTO photocatalyst can achieve a significant improvement in OWS efficiency compared to pristine single-crystal BTO, making it a promising candidate for practical solar energy conversion applications.