Asymmetric Electron Redistribution in Niobic-Oxygen Vacancy Associates to Tune Noncovalent Interaction in CO₂ Photoreduction

The role of vacancy associates in photocatalytic CO₂ reduction is an open question. Herein, the Nb─O vacancy associates (V_Nb─O) are engineered into niobic acid (NA) atomic layers to tailor the CO₂ photoreduction performance. The intrinsic charge compensation from O to Nb around Nb─O vacancy associates can manipulate the active electronic states, leading to the asymmetric electron redistribution. These local symmetry breaking sites show a charge density gradient, forming a localized polarization field to polarize nonpolar CO₂ molecules and tune the noncovalent interaction of reaction intermediates. This unique configuration contributes to the 9.3 times increased activity for photocatalytic CO₂ reduction. Meantime, this V_Nb─O NA also shows excellent photocatalytic activity for NO₃⁻–NH₄⁺ synthesis, with NH₄⁺ formation rate up to 3442 µmol g⁻¹ h⁻¹. This work supplies fresh insights into the vacancy associate design for electron redistribution and noncovalent interaction tuning in photocatalysis.