Quinonoid π-Conjugated Interfaces Drive Exciton Dissociation for CO2 Photoreduction on Perovskite Nanocrystals

Abstract

Halide perovskite nanocrystals are promising photocatalysts for CO2 reduction due to their strong light absorption, defect tolerance, and tunable excited-state properties, but their practical performance remains limited by tightly bound excitons, rapid charge recombination, and inefficient interfacial electron delivery. Here, we report an anthraquinone (AQ)-modified CsPbBr3 nanocrystal photocatalyst (CPB/AQ) in which the redox-active π-conjugated AQ ligand functions as an interfacial electron relay and molecular electric-field modulator. Experimental and theoretical analyses collectively reveal that AQ creates an additional interfacial charge-transfer pathway, strengthens the light-induced surface potential difference from 170 to 270 mV, and decreases the exciton binding energy from 44.05 to 40.74 meV. Consequently, CPB/AQ achieves a CO yield of 433.50 μmol g–1 within 3 h under AM 1.5G irradiation, 4.54 times that of pristine CPB, and maintains stable CO evolution during a 25 h test. Isotopic 13CO2 tracing verifies that CO originates from CO2 reduction, while in situ FTIR spectroscopy demonstrates enhanced CO2 adsorption/activation and accelerated formation of *COOH and *CO intermediates on CPB/AQ. This work highlights molecularly gated interfacial electric-field regulation as an effective strategy for overcoming charge-transfer bottlenecks in perovskite nanocrystal photocatalysis.