Electron-Transfer-Induce Optical Modulation and Growth Mechanism of Au–ZnO Heterogeneous Nanopyramids

Au–ZnO heterogeneous nanoparticles (NPs) were successfully synthesized, and the intrinsic correlation between their spectral evolution and interfacial growth mechanism was systematically elucidated. With increasing Au content, the SPR absorption peak of Au exhibits a pronounced red shift, while the defect-related emission of ZnO is suppressed and the band-edge emission becomes broadened. These spectral variations are closely coupled with the interfacial growth process. Interfacial electron transfer and the formation of a Schottky barrier induce charge redistribution within ZnO and reduce oxygen vacancies, enabling ZnO to preferentially nucleate on the Au surface and subsequently evolve into a pyramidal structure. The resulting morphological transformation further enhances electron depletion and plasmonic coupling, lowering the effective plasmonic energy of Au and deepening the SPR red shift. Quantitative analysis based on Mie theory shows that approximately 12% of the free electrons in Au participate in interfacial transfer, confirming the cooperative role of strong electronic coupling in governing both growth dynamics and optical responses. This study provides deeper insight into the photophysical mechanisms of Au–ZnO heteronanocrystals and offers guidance for designing noble metal–semiconductor composites with tunable optoelectronic properties.