Oxygen Evolution Reaction Driven by Plasmon-Induced Hot Holes and S-Scheme Synergy in CuS@Polypyrrole Nanorods

Copper sulfide (CuS) exhibits strong near-infrared local surface plasmon resonance (LSPR) but suffers from severe photocorrosion in alkaline media. To address this, we engineered a core-shell CuS@polypyrrole (CuS@PPy) heterostructure on copper foam. The optimized CuS@PPy-600 achieves exceptional oxygen evolution reaction (OER) performance with overpotentials of 383 mV (dark) and 333 mV (light) at 100 mA·cm^-2, 81 mV lower than pristine CuS under illumination and a Tafel slope of 16.9 mV·dec^-1 under light. The PPy shell enables dual synergistic mechanisms: (i) S-scheme heterojunction facilitating charge separation via interfacial electron transfer (XPS: Cu 2p ↑ 0.3 eV, N 1s ↓ 0.4 eV), suppressing recombination; and (ii) plasmonic hot-hole extraction where PPy's conductive π-matrix injects LSPR-generated hot holes into OER sites, accounting for 71% of activity gain under >800 nm light. This synergy delivers >24 h stability (<5% decay) by preventing CuS corrosion while optimizing plasmonic energy utilization.