Plasmon-induced Charge Separation and Accumulation in Ag 2 S/Cu 2-x S S-Scheme Junction for Wide-Light-Driven Photothermal-Assisted Photocatalysis

Abstract

Step-scheme junction has demonstrated great potential in photocatalysis owing to the unique charge separation mechanism. However, the further acceleration of charge separation and extension of light response remain challenging. Herein, a plasmoninvolved S-scheme junction is demonstrated in Ag 2 S/Cu 2-x S nanotubes, which show efficient photocatalytic hydrogen generation driven by enhanced light absorption, notable photothermal conversion, and ultrafast charge separation. Due to the plasmonic excitation and hollow tubular architecture, the hybrids can efficiently harvest light in a wide region. Meanwhile, the well-matched band alignment of Ag 2 S and Cu 2-x S confers upon the hybrids a built-in electric field and a plasmon-involved S-scheme chargetransfer pathway for charge separation. The transient absorption tests indicate that the ultrafast plasmon-induced hot electron injection from Cu 2-x S to Ag 2 S effectively promotes the recombination of electrons in Cu 2-x S with holes in Ag 2 S within the Sscheme junction. As a result, the lifetimes of hot holes on the trap states Cu 2-x S and electrons of the conduction band of Ag 2 S are prolonged, leading to the accumulation of holes and electrons on the high oxidation and reduction potentials, respectively. Under light irradiation (>420 nm), the Ag 2 S/Cu 2-x S achieve a highly-enhanced photothermalassisted photocatalytic hydrogen evolution rate, which is much higher than that of Ag 2 S and Cu 2-x S. This study provides valuable insights for the design of efficient photocatalysts based on S-scheme heterojunctions for energy conversion.