Hierarchical Self-Assembled CuS@CdS-Pt Core-Shell Heterojunctions with Photothermal Effect for Photoelectrochemical Water Splitting.

Abstract

Photoelectrochemical (PEC) water splitting provides a sustainable pathway for hydrogen production, yet achieving efficient and stable photoanodes continues to be a formidable obstacle. Herein, a core-shell CuS@CdS-Pt photoanode is constructed via in situ hydrothermal self-assembly followed by Pt surface modification. The Z-scheme heterojunction between CdS and CuS generates the built-in electric field (IEF), stimulating spatial separation of photogenerated electron-hole pairs while preserving strong redox capability. Building on this, a synergistic dual-thermal effect is proposed and demonstrated. Specifically, the photothermal effect of CuS enhances thermal conductivity via non-radiative relaxation-induced phonon transport along the lattice, accelerating water oxidation kinetics and boosting charge separation efficiency. Meanwhile, the localized surface plasmon resonance (LSPR) effect of surface-decorated Pt strengthens the local electromagnetic field, injects hot electrons, and provides additional thermal energy, synergistically regulating carrier separation and transport. Consequently, the optimized CuS@CdS-Pt photoanode achieves a photocurrent density of 3.92 mA cm-2 at 1.23 VRHE under near-infrared (NIR) auxiliary irradiation, a Faradaic efficiency of 90.3%, and retains 90% initial photocurrent after 20 h of uninterrupted running, to our knowledge exceeding all prior CdS-based photoanodes. This work integrates heterojunction engineering with the dual-thermal effect, providing a new strategy for designing high-efficiency, durable photoanodes for PEC water splitting.