An Ester-Functionalized Bidentate Titanium-based Metal-Organic Framework with Visible-Light Enhanced Activity for CO2 Photoreduction

ChemSusChem. 2024 Dec 6;17(23):e202400936. doi: 10.1002/cssc.202400936. Epub 2024 Aug 7.

Abstract

The limited visible light response is a critical drawback that hampers the photocatalytic efficacy of Ti-MOFs. However, study concerning the enhancement of the visible-light response of Ti-MOFs is still in its nascent stage. In this study, we employ the 'dual-ligand decrystallization strategy' to manipulate the electronic environment of Ti4+, leading to the synthesis of three ester-functionalized bidentate Ti-MOFs with enhanced visible light response. Our findings reveal that this approach not only reduces the bandgap of Ti-MOFs but also enhances their photocatalytic activity for carbon dioxide reduction. Specifically, compared to the bandgap of Ti-BPDC at 2.98 eV, the bandgap of Ti-BPDC-CA 1 : 2 has been reduced to 2.14 eV. Moreover, Ti-BPDC-CA 1 : 2 exhibits extraordinary photocatalytic activity with the formic acid (HCOOH) production rate of 617 μmol g-1 h-1 with over 99.5 % selectivity, which is 3.47 times higher than that of Ti-BPDC. Besides providing a cost-effective strategy for enhancing the visible light response of Ti-MOFs, our study also serves as an illustrative example for establishing the correlation between electronic structure and optical properties.

Keywords: CO2 reduction; Ester functionalization; Narrow bandgap; Ti-MOFs; Visible-light enhanced photocatalysis.