Phase‐Change‐Induced Dual Electric Fields Over Atomically Bonded MicCu 2 O@Cu‐TCPP Heterojunctions for Synergistic Photocatalysis

ABSTRACT Photocatalytic technology is essential for sustainable chemical synthesis but is constrained by charge recombination and thermal accumulation, which reduce quantum efficiency. Although heterojunctions enhance charge separation, conventional systems fail to alleviate thermally enhanced recombination. This study addresses these challenges through atomic‐level interface engineering of a phase‐change‐modulated MicCu 2 O@Cu‐TCPP, pioneering the exploitation of temperature gradients generated during phase transitions to establish a thermal electric field that operates synergistically with the intrinsic built‐in electric field, thereby markedly enhancing charge‐separation efficiency. Under exothermic photocatalytic conditions, the encapsulated phase‐change domain effectively absorbs reaction heat and generates microscale temperature differentials across the heterointerface, resulting in a 4.3‐fold enhancement in electric field strength compared to pristine Cu 2 O. Concurrently, the delocalized π‐electron system of Cu‐TCPP furnishes complementary light absorption to Cu 2 O, broadening the spectral responsiveness into previously underutilized regions. As a result, the MicCu 2 O@Cu‐TCPP heterojunction delivers an almost eightfold increase in benzylamine oxidation conversion relative to Cu 2 O alone. By integrating phase‐change thermal regulation with atomically bonded p‐n junctions and dual electric‐field coupling, our strategy unlocks a new class of intelligent catalytic materials capable of multi‐field synergy, and provides critical insights for the precision control of advanced photocatalytic processes.