Direct evidence of IR-driven hot electron transfer in metal-free plasmonic W18O49/Carbon heterostructures for enhanced catalytic H2 production

Plasmonic nanostructures have received significant attention in the field of solar-to-fuels conversion, because they can collect and utilize abundant low-energy photons to generate high-energy hot electrons for producing green chemical fuels. However, the ultrafast relaxation process of hot electron often leads to poor quantum yields of plasmonic nanostructures. Herein, we construct the one-dimensional W18O49/Carbon heterostructure for employing low-cost electrospun carbon fibers as the “electron mediator” to hinder the relaxation of hot electron in plasmonic W18O49 nanowires. We confirm that the IR-excited plasmonic hot electrons in W18O49 nanowires can quickly transfer to carbon fibers within only ∼50 fs in the W18O49/C heterostructure. This kinetics time is much shorter than the relaxation time of these hot electrons from high-energy surface plasmon (SP) to the ground state in W18O49 nanowires (∼5.5 ps). As a result, upon low-energy IR-light excitation, the W18O49/C heterostructures exhibit nearly 2-fold enhancement on the catalytic H2 production from ammonia borane as compared to single W18O49 nanowires. Wavelength-dependent catalytic tests further indicate that this plasmon-enhanced catalytic activity is induced by the ultrafast transport process of plasmonic hot electron due to the localized surface plasmon resonance.