Surface-amino-induced boosting solar conversion of CO2 to CO over natural metal-free catalyst

Abstract

Design and construction of visible-light-responsive and low-cost catalyst to improve photocatalytic CO2 reduction efficiency are highly urgent due to rapid increment of CO2 emission. Herein, a facile but effective strategy is proposed to synthesize heteroatoms-doped porous treated rape pollen (TRP) and NH2-functionalized TRP for CO2 reduction. Heteroatoms doping can accelerate photoinduced charge transfer between neighboring carbon atom. The introduction of NH2- group offers effective sites to boost CO2 adsorption, which is beneficial to facilitate CO2-to-CO conversion. The experimental results indicate that TRP-NH2 exhibits visible-light-driven CO formation rate of 1165.3 μmol h−1 g−1 in the gas-solid reaction system without co-catalysts or sacrificial agents, which is 2.4 and 70.1 times than those of TRP (488.4 μmol h-1 g-1) and g-C3N4 (16.6 μmol h-1 g-1), and exceeds reported state-of-the-art carbon-based photocatalysts. The theoretical investigation shows that the incorporation of NH2- group can improve its charge density and converge more electrons to adsorb CO2 molecules. In situ Fourier transform infrared (FT-IR) spectroscopy spectra disclose that the COOH* radical is the main intermediate. The findings reveal the correlation between surface NH2- group and photocatalytic CO2 reduction performance and can be extended to other sustainable metal-free based catalysts for solar-driven CO2 reduction.