Charge Transfer Mechanism and Boosted Photocatalytic H ₂ O ₂ Synthesis Over Cu _2−x S@Au Schottky Junctions

ABSTRACT The photocatalytic synthesis of hydrogen peroxide (H ₂ O ₂ ) is a promising green route, yet its efficiency is generally limited due to insufficient photoelectrons and weak O ₂ adsorption at the active sites of photocatalysts. To address these issues, herein Cu _2−x S@Au Schottky junctions have been constructed by decorating Au nanoparticles on the surface of hollow cubic Cu _2−x S nanoboxes. It is demonstrated that the formation of Cu _2−x S@Au Schottky junctions results in the thermoelectron diffusion from Au to Cu _2−x S as the former has a higher Fermi level than the latter. The thermoelectron diffusion process induces electron deficiency in Au nanoparticles, thereby enhancing O ₂ adsorption on the Au active sites. During the photocatalysis process, the photogenerated electrons in Cu _2−x S are driven by the created Cu _2−x S@Au interface electric field to reach the Au active sites for photoreduction reactions. Additionally, the localized surface plasmon resonance, photothermal effect, and unique hollow architecture of the Cu _2−x S@Au photocatalysts are also conducive to the photocatalysis. The H ₂ O ₂ yield rate of the optimal photocatalyst CS@Au‐7 reaches 935.8 µmol g ⁻¹ h ⁻¹ , exhibiting a 2‐fold enhancement when compared to that of Cu _2−x S (467.1 µmol g ⁻¹ h ⁻¹ ). This work offers an intriguing strategy for designing efficient photocatalysts in photocatalytic H ₂ O ₂ synthesis.