Tuning Non‐Metallic Plasmonic Coupling Through Nanoscale “Antenna‐Reactor‐Hot Core” Configuration for Photothermal Catalytic Hydrogen Production Under High Temperature

Abstract Noble metals, due to surface plasmon resonance effects, have been widely employed in solar energy‐driven photothermal catalytic reactions such as water splitting, however, cost‐effective alternatives necessitate precise nanostructuring to compete effectively with noble metals. This study presents the design and synthesis of a hierarchical nanoarchitecture, featuring an “antenna‐reactor‐hot core” pattern comprising Cu _2‐x Se@TiO ₂ @WO _3‐x , aimed at enhancing photothermal catalytic water splitting efficiency through plasmonic coupling. The optimized Cu _2‐x Se@TiO ₂ @WO _3‐x demonstrates exceptional broadband light absorption and achieves a remarkable hydrogen evolution rate of 418.0 µmol g ⁻¹ under visible‐near infrared irradiation at 573 K, without the use of metallic co‐catalysts. Critical to this performance is the precisely engineered TiO ₂ interlayer, which spatially aligns perfectly with the plasmonic “hot spots” between Cu _2‐x Se and WO _3‐x . This alignment amplifies localized electromagnetic fields and facilitates ultrafast hot‐electron injection into catalytic sites. Femtosecond transient absorption spectroscopy elucidates the carrier dynamics and plasmonic coupling effects, demonstrating how enhanced interfacial charge transfer synergizes with structural optimization to boost photocatalytic performance. Finite‐element simulations establish a direct correlation between non‐metallic plasmonic coupling and locally enhanced electric fields, revealing a TiO ₂ ‐tuned “hot spots” shell mechanism. This work lays down a universal framework for designing hybrid plasmonic systems towards solar fuel production.