Synergizing Schottky/S-Scheme Dual-Junction With Cu/Pb Dual-Site in a 0D/3D Cu@CsPbBr₃/g-C₃N₄ Heterojunction for...

The CO₂ photoreduction to multi-carbon products, particularly C₂H₄, remains challenging due to inefficient charge separation, high C-C coupling barriers, and limited mass transport. Herein, we designed a mixed-dimensional heterostructure integrating S-scheme and Schottky junctions, with Cu-decorated CsPbBr₃ nanocrystals anchored on three-dimensionally ordered macroporous g-C₃N₄ (Cu@CPB/3DOM-CN). In situ x-ray photoelectron spectroscopy and femtosecond transient absorption spectroscopy demonstrate dual internal electric fields driving rectified spatial carrier separation with strong redox capability. Strong metal-support interaction induces charge redistribution, generating polarized Cu/Pb dual sites that lower the energy barrier for *CO hydrogenation to *CHO. In situ diffuse reflectance infrared Fourier transform spectroscopy combined with density functional theory calculations provides direct evidence that dual sites promote asymmetric *CO-*CHO coupling. The 3DOM framework functions as a nanoreactor, enhancing the local enrichment of CO₂ and key intermediates to promote coupling kinetics. The optimized catalyst exhibits distinct selectivity across varying CO₂ concentrations, achieving 52.4% C₂H₄ selectivity (26.37 µmol g^-1 h^-1) in pure CO₂, which increases to 77.6% and 65.1% under 5% and 0.04% CO₂ (balanced with Ar), respectively, highlighting its remarkable adaptability to diverse application scenarios. This work establishes a triple synergy of directional charge transport, active-site polarization, and reactant enrichment for efficient and selective CO₂-to-C₂H₄ conversion.