Plasmon Resonance Coupling and Amplification Promoting Photothermal Catalytic Hydrogen Production from Water and Seawater under High Temperature

Solar-driven photocatalytic water splitting is a promising approach for renewable hydrogen production from water, but most photocatalysts suffer from limited near-infrared light absorption and low carrier utilization efficiency. In this research, separated plasmonic material modified TiO2 photocatalysts have been developed, with the objective of leveraging local surface plasmon resonance (LSPR) effects of metals and nonmetals for broadening solar spectrum absorption and boosting energetic carrier generation during photothermal catalytic hydrogen production. Particularly, Ag and WO3–x nanoparticles co-modified TiO2 nanorods (Ag-WO3–x/TNR) demonstrated exceptional photothermal catalytic H2 production under UV–vis–near-IR (UV–vis–NIR) irradiation or vis–NIR irradiation at 573 K. The apparent quantum efficiencies for H2 production are calculated about 6.65% at 400 nm and 4.08% at 600 nm irradiation. Femtosecond transient absorption spectroscopy measurements revealed the rapid transfer of electrons from WO3–x to adjacent TiO2, and additional Ag deposition promoted the hot electron injection process. Finite element method simulations corroborated that the coupling of plasmonic Ag and WO3–x nanoparticles with appropriate distances influences the distribution of the local electromagnetic field, leading to a significant enhancement of the electric field at specific surface sites. Moreover, temperature-variation tests and in situ characterizations on catalysts elucidated the influences of a high-temperature environment on the plasmon-induced LSPR effect, as well as on the intrinsic photophysical and photochemical behaviors of semiconductors. The photothermal catalytic H2 production efficiency was further improved when simulated seawater was used compared to pure water.