Asymmetric nano-disordering with favored charge and reaction kinetics to boost CO2 photoreduction with high stability

Abstract

CO₂ photoreduction is a promising approach to address global energy crisis and achieve carbon neutralization, yet the activity and stability are still far from satisfactory because of sluggish charge and reaction kinetics. Herein, we constructed a nanoscale asymmetric structure by integrating amorphous and crystalline nano-domains on two-dimensional ultrathin TiO₂ nanosheets, which exhibits a boosted CO₂ reduction activity with a CO production rate of 55.61 μmol g⁻¹ h⁻¹, and a prolonged stability with 8-cycle tests of 48 h in total, significantly outperforming its symmetric counterparts. In situ light-assisted surface photovoltage microscopy under CO₂ atmosphere and density functional theory calculations suggest that the asymmetric Fermi levels of the ordered and disordered nano-domains lead to electron density gradient along the nano-interfaces, enhancing the separation and migration of photogenerated charge carriers. Also, due to the asymmetric electron acceptor-donor capability of the two domains, the disordered domain serves as active sites for CO₂ reduction, while the ordered domain for water oxidation. The inverse electron flow directions on the two domains help to close the loop of electron transfer between redox sites, accelerating surface reaction kinetics. The simultaneous improvements of charge and reaction kinetics contribute to the excellent performance of the asymmetric catalyst, providing a new paradigm for designing photocatalysts through nanoscale disorder engineering.