The synergistic effect of localized surface plasmon resonance (LSPR) coupled with ferroelectric polarization in plasmonic-ferroelectric WO_3-x/K₄Nb₆O₁₇ heterojunction accelerates spatial separation and directional extraction of charge carriers, thereby ultimately boosting photocatalytic CO₂ reduction integrated with benzylicalcohol C─C coupling.

Abstract

Integrating solar-driven CO₂ reduction with organic oxidation is regarded as an ideal strategy for achieving carbon neutrality. However, further enhancement of photocatalytic efficiency is persistently blocked by low photogenerated carrier yields and unavoidable fast bulk electron/hole recombination. Herein, we propose to design a plasmonic-ferroelectric heterojunction (WO_3-x/K₄Nb₆O₁₇), which enhances localized electromagnetic field and ferroelectric polarization field simultaneously through the cooperative coupling of localized surface plasmon resonance (LSPR) effect in WO_3-x and ferroelectric polarization in K₄Nb₆O₁₇, thereby not only promoting energetic hot-carriers generation, but also accelerating bulk charge separation. Ultimately, hot-electrons and photoelectrons are directionally transferred and extracted to K₄Nb₆O₁₇ surface for CO₂ reduction, whereas massive holes are accumulated in WO_3-x for benzylicalcohol activation. Under mild conditions, WO_3-x/K₄Nb₆O₁₇ exhibits superior CO yield (294.76 µmol g⁻¹ h⁻¹), which is 9.87 and 6.27-folds higher than that of K₄Nb₆O₁₇ and WO_3-x, respectively. Meanwhile, compared to the simple dehydrogenation of benzylicalcohol to benzaldehyde in K₄Nb₆O₁₇ and WO_3-x, WO_3-x/K₄Nb₆O₁₇ prefers to trigger benzylicalcohol C─C coupling for directed production of more value-added hydrobenzoin (313.15 µmol g⁻¹ h⁻¹). This work would open a conceptual vista for designing multifield coupling structures to facilitate charge spatial separation and directional transfer, which would inspire further establishment of efficient novel photocatalysts and solar-to-fuel conversion systems to meet the green and sustainable development goals.