Amorphous surficial sites and yolk@shell regulation of Au@ZnS hetero-nanorods for plasmon-enhanced photocatalytic CO₂ reduction

Noble metal@semiconductor hetero-nanocrystals exhibit great potential in solar energy applications, especially for those with yolk-shell structures enabling efficient light-scattering and abundant active sites. Further rational modulations of their surficial sites for enhanced adsorption properties and directional charge migrations are significantly important. In this work, we design and synthesize Au@ZnS yolk-shell hetero-nanorods providing amorphous and plasmonic Au nanorod/ZnS microcavities via an aqueous cation exchange strategy. The resulting Au@ZnS yolk-shell hetero-nanorods demonstrate tunable surficial states, in which the hetero-nanocrystals with amorphous surfaces and plasmon enhancement (Au@ZnS-AS Y-S NRs) exhibit excellent photocatalytic activity for CO₂ reduction, yielding a CO production rate of 112.09 μmol·g⁻¹·h⁻¹ with >90% selectivity under visible light irradiation (λ >420 nm). Photocurrent measurements reveal that surface amorphous modification and yolk-shell hetero-interface regulation significantly improve the charge dynamics, whereas transient absorption spectroscopy further verifies that the introduction of amorphous structure promotes charge carrier separation and transfer. In situ spectroscopy results further confirm the stronger CO₂ adsorption capacity and faster conversion efficiency of Au@ZnS-AS Y-S NRs. As verified by radical trapping experiments and theoretical calculations, the amorphous layer, in particular, enhances the adsorption and activation capacity, thereby improving the overall catalytic performance. The achieved photocatalytic performance demonstrates the potential of co-regulating both the surface states and plasmonic yolk-shell microcavities for advancing sunlight-driven synthesis.