Heterostructured perovskite nanocrystals for water stable plasmon-enhanced photoelectrocatalysis

Perovskite photoelectrocatalysis enables solar-driven conversion of CO₂ to value-added chemicals, but instability in water and insufficient C–C coupling still constrain performance. Herein, we present a synergistic approach for aqueous-phase CO₂ conversion that combines perovskite-based photoelectrocatalysis with localized surface plasmon resonance (LSPR) enhancement. To address the inherent instability of lead-halide perovskites, we developed a modified hot-injection route that enables the in situ formation of water-stable CsPbBr₃@TiO₂ core–shell nanoparticles. Titanium butoxide and water were introduced after Cs-oleate injection, enabling controlled TiO₂ shell growth without post-treatment. Electron microscopy, XRD, and XPS confirm the core–shell architecture, while optical/electrical probes indicate efficient charge separation across the CsPbBr₃/TiO₂ junction. Subsequently, we investigated electrocatalytic, photocatalytic, and photoelectrochemical carbon dioxide reduction (CO₂RR) on CsPbBr₃@TiO₂/Au and CsPbBr₃@TiO₂. Gas chromatography revealed tunable product selectivity, yielding H₂, CO, CH₄, and multicarbon (C₂, C₃) products including C₂H₄ (ethylene) and C₃H₆ (propene). Our main findings indicate that the CsPbBr₃@TiO₂/Au exhibits high selectivity toward C₃ (propene) in photocatalysis and C₂ (ethylene) in photoelectrochemistry, reaching up to 70% and 58%, respectively. These results highlight perovskite heterostructures as a viable platform for efficient CO₂ utilization and the sustainable production of value-added C₂/C₃ chemicals.