Selective orbital modulation via interfacial confinement enables highly selective CO2 photoreduction

This is the authors' abstract. We don't add key points for this paper.

A hierarchical SiO 2 @In 2 S 3 /In 2 O 3 S-scheme heterojunction is presented as a highly selective photocatalyst for pure-water CO 2 reduction. It is fabricated via a spatially confined synthesis strategy utilizing SiO 2 -mediated phase reconstruction, generating a vacancy-rich homologous heterointerface. Under full-spectrum irradiation, the optimized photocatalyst achieves a CO evolution rate of 714.95 μmol g −1 h −1 with 86.05% selectivity among carbonaceous products in pure water without sacrificial agents. Physicochemical measurements, including in situ DRIFTS, KPFM, and DFT calculations, have been employed to probe the photocatalytic mechanism. The combined analyses reveal that the S-scheme charge transfer preserves strong redox potentials within the inner core. Concurrently, the ultrathin nature of the outer oxide shell (~3.5 nm) enables these energetic electrons to reach the surface via quantum tunneling and strong interfacial coupling. Furthermore, a unique interfacial selective orbital modulation effect downshifts the In-p band center via asymmetric O-In-S configurations. This orbital modulation selectively destabilizes strongly bound *CO intermediates and maintains high affinities for *COOH, thereby overcoming the thermodynamic *CO desorption bottleneck and suppressing further over-hydrogenation beyond CH 4 by elevating the *CHO formation barrier. The results point to a highly efficient CO 2 reduction paradigm in which reactivity is promoted by homologous phase reconstruction, quantum tunneling, and interfacial selective orbital modulation.