Near-Infrared-Active Periodic Plasmonic Heterostructures Enable High-Efficiency Photoelectrochemical Hydrogen Production

Plasmon-mediated photoelectrocatalysis has been regarded as a promising avenue to boost solar energy conversion. However, the major problem of most plasmonic nanostructures is that they rely heavily on expensive noble metals (such as Au and Ag), along with the localization of their surface plasmon resonance (SPR) in the spatial distribution, which limits the improvement of photoelectrochemical performance and hinders their practical application. Here, we design a near-infrared (NIR) light-active periodic plasmonic heterostructure composed of semimetallic Bi nanoparticles and Bi 3 (Se n Te 1– n ) 2 ternary alloy nanowires, which are able to extend the light absorption range and utilize the SPR effect more efficiently. Compare to noble metals, metallic Bi can excite the SPR effect in the whole ultraviolet-to-NIR range. The periodic heterostructure can alleviate the localization of the SPR and then improve the charge transfer and redox kinetics through the efficient utilization of local electromagnetic fields and photothermal heating. In consequence, the photoanode achieves an incident photon-to-current conversion efficiency of 22% at 800 nm and a photocurrent density of 13.8 mA cm –2 at 0.85 V RHE under visible light without any cocatalysts.