Two dipole materials are stacked into a D-scheme van der Waals heterojunction. The large built-in polarization field facilitates the desired charge transfer and generates a large driving force for redox reactions, boosting photocatalytic overall water splitting. [Display omitted] • Dipole-scheme (D-scheme) heterojunction photocatalysts composed of polar materials are theoretically proposed and the material realization was achieved by first-principles calculations. • The competing relationship between the interfacial polarization field and depolarization field caused by the charge transfer was quantitatively investigated. • More efficient carrier separation could be expected in D-scheme heterojunctions owing to the large built-in field induced by interfacial polarizations, which addresses the challenges of type-Ⅱ heterojunction photocatalysts. • A prototype of high-performance D-scheme heterojunction photocatalyst for overall water splitting, PtSeTe/LiGaS 2 , was explored to present the promising applications of the D-scheme model in novel photocatalysis and photovoltaics. The high recombination rate of photogenerated carriers is the bottleneck of photocatalysis, severely limiting the photocatalytic efficiency. Here, we develop a dipole-scheme (D-scheme for short) photocatalytic model and materials realization from first-principles dipole calculations. The D-scheme heterojunction not only can effectively separate electrons and holes by large polarization fields, but also boosts photocatalytic redox reactions with high driving photovoltages and with less carrier loss. After developing the D-scheme model, we then theoretically propose a D-scheme heterojunction prototype with two real polar materials, PtSeTe/LiGaS 2. Such D-scheme photocatalyst exhibits a high capability of the photogenerated carrier separation and near-infrared light absorption. Moreover, our calculations of Gibbs free energies imply a high ability of hydrogen evolution reaction and oxygen evolution reaction by a large driving force. The proposed D-scheme photocatalytic model is generalized and paves a valuable route for significantly improving the photocatalytic efficiency. [ABSTRACT FROM AUTHOR]