Plasmon coupling induced intense light absorption and near-field enhancement have vast potential for high-efficiency photocatalytic applications. Herein, (Au/AgAu)@CdS core–shell hybrids with strong multi-interfacial plasmon coupling were prepared through a convenient strategy for efficient photocatalytic hydrogen generation. Bimetallic Au/AgAu cores with an adjustable number of nanogaps (from one to four) were primarily synthesized by well-controlled multi-cycle galvanic replacement and overgrowth processes. Extinction tests and numerical simulations synergistically revealed that the multigap Au/AgAu hybrids possess a gap-dependent light absorption region and a local electric field owing to the multigap-induced multi-interfacial plasmon coupling. With these characteristics, hetero-photocatalysts prepared by further coating of CdS shells on multigap Au/AgAu cores exhibited a prominent gap-dependent photocatalytic hydrogen production activity from water splitting under light irradiation (λ > 420 nm). It is found that the hydrogen generation rates of multigap (Au/AgAu)@CdS have an exponential improvement compared with that of pure CdS as the number of nanogaps increases. In particular, four-gap (Au/AgAu)@CdS core–shell catalysts displayed the highest hydrogen generation rate, that is 96.1 and 47.2 times those of pure CdS and gapless Au@CdS core–shell hybrids. These improvements can be ascribed to the strong plasmon absorption and near-field enhancement induced by the multi-interfacial plasmon coupling, which can greatly improve the light-harvesting efficiency, offer more plasmonic energy, and boost the generation and separation of electron–hole pairs in the multigap catalysts.

In this review, the basic principles of plasmon-enhanced SHG, different methods to enhance the SHG intensity of metal nanostructures, and related applications of SHG based on metal nanostructures are introduced.

Ti₃C₂T_x/Bi₂S₃ hybrids with excellent photothermal conversion and photothermal-assisted photocatalytic performance were prepared for solar-driven water purification via the combination of water evaporation and photocatalytic degradation.

Developing high-performance photothermal materials and unraveling the underlying mechanism are essential for photothermal applications. Here, photothermal performance improved by strong interaction between plasmon and topological surface state (TSS) is demonstrated in Bi ₂ Se ₃ /Cu _{2- x} S nanowires. This hybrid, which Cu _{2- x} S nanosheets were grown on Bi ₂ Se ₃ nanowires, leverages the plasmon resonance and TSS-induced optical property, generating wide and efficient light absorption. A series of tests reveals the strong resonance coupling, TSS-induced hot electron injection, and plasmon-induced hot hole relaxation within the hybrids, endowing the Bi ₂ Se ₃ /Cu _{2- x} S with excellent photothermal performance. By integrating the hybrids into a hydrogel with a thermoelectric module, the Bi ₂ Se ₃ /Cu _{2- x} S evaporator achieves a remarkable water evaporation rate of 3.67 kilograms per square meter per hour with a solar-to-vapor efficiency of 95.2%, and a maximum output power of 1.078 watts per square meter under simulated sunlight irradiation. Moreover, a conical mirror was introduced to the device, which greatly enhances the evaporation rate and maximum output power without additional energy input.

By controlling the content of Cd²⁺, lateral Au–CdSe heterorods with better photocatalytic properties under visible light were synthesized.