NH2-UiO-66/g-C3N4/CdTe composites for photocatalytic CO2 reduction under visible light

Fengyang Yu,Xuezhao Li,Xiaoshuang Shen,Chunying Duan,Liyong Chen

doi:10.1063/1.5120528

Abstract

To boost the photocatalytic activity of NH2-UiO-66 toward CO2 under visible light, CdTe quantum dots and g-C3N4 nanocrystals were introduced to form NH2-UiO-66/g-C3N4/CdTe composites via a two-step synthetic strategy. g-C3N4 and CdTe in different visible light ranges possessed a strong absorption ability, and, thereby, greatly extended the range of photoresponsive wavelength of the composites. Mott-Schottky analysis revealed that the energy level of the conduction band of g-C3N4 and CdTe was higher than the LUMO level of NH2-UiO-66, benefiting for the photogenerated carriers separation and electron injection from g-C3N4 and CdTe to NH2-UiO-66, leading to a high concentrated Zr (iii) formation. Finally, the NH2-UiO-66/g-C3N4/CdTe composites exhibited the superior photocatalytic performance for CO2 conversion in the acetonitrile/ethanol system upon visible light irradiation (≥400 nm) with a HCOOH generation rate of 24.6 µmol g−1 h−1 that was ∼7.5 times higher than that of NH2-UiO-66 alone.

Highlights

Three-dimensional, highly porous, crystalline metal-organic frameworks (MOFs) have attracted considerable attention in gas absorption/separation and catalysis.1–4 Their tunable components and diversified porous structures are favorable for enrichment and activation of substrates in the catalytic process, accounting for the improvement of the MOFs’ catalytic activity
The enhanced photocatalytic performance of NH2-UiO-66 was tremendously dependent on the photosensitization effect of graphitic C3N4 (g-C3N4) nanocrystals and CdTe quantum dots (QDs) to generate a large amount of Zr (III) to reduce CO2
As for g-C3N4, the strong C1s peak at 287.9 eV was indexed to sp2 C atoms connected with N atoms, whereas the C1s peak with low intensity at 284.4 eV could be originated from C==C [Fig. S4(b)]

Summary

Introduction

Three-dimensional, highly porous, crystalline metal-organic frameworks (MOFs) have attracted considerable attention in gas absorption/separation and catalysis.1–4 Their tunable components and diversified porous structures are favorable for enrichment and activation of substrates in the catalytic process, accounting for the improvement of the MOFs’ catalytic activity. After successive reaction for 12 h, the photocatalytic activity of the NH2-UiO-66/g-C3N4/CdTe composites was decreased to 80% compared to the initial stage (2 h) with the HCOOH generation rate of 19.8 μmol g−1 h−1 [Fig. 4(c)].

Results

Conclusion