Metal-organic framework membranes with single-atomic centers for photocatalytic CO2 and O2 reduction

Yu-Chen Hao,Wen-Yan Gao,Chun-Hua Yan,An-Xiang Yin,Jiani Li,Qinghua Zhang,Li-Wei Chen,Xin Su,Bo Wang,Miao Shu,Ya-Wen Zhang,Rui Si,Siwu Li,Xiao Feng,Zi-Long Yu,Lin Gu,Yu Guo

doi:10.1038/s41467-021-22991-7

Abstract

The demand for sustainable energy has motivated the development of artificial photosynthesis. Yet the catalyst and reaction interface designs for directly fixing permanent gases (e.g. CO2, O2, N2) into liquid fuels are still challenged by slow mass transfer and sluggish catalytic kinetics at the gas-liquid-solid boundary. Here, we report that gas-permeable metal-organic framework (MOF) membranes can modify the electronic structures and catalytic properties of metal single-atoms (SAs) to promote the diffusion, activation, and reduction of gas molecules (e.g. CO2, O2) and produce liquid fuels under visible light and mild conditions. With Ir SAs as active centers, the defect-engineered MOF (e.g. activated NH2-UiO-66) particles can reduce CO2 to HCOOH with an apparent quantum efficiency (AQE) of 2.51% at 420 nm on the gas-liquid-solid reaction interface. With promoted gas diffusion at the porous gas-solid interfaces, the gas-permeable SA/MOF membranes can directly convert humid CO2 gas into HCOOH with a near-unity selectivity and a significantly increased AQE of 15.76% at 420 nm. A similar strategy can be applied to the photocatalytic O2-to-H2O2 conversions, suggesting the wide applicability of our catalyst and reaction interface designs.

Highlights

The demand for sustainable energy has motivated the development of artificial photosynthesis
The high porosity of SA/metalorganic framework (MOF) membranes allows the creation of gas-membrane-gas (GMG) configuration, which boosts the highthroughput diffusion of humid CO2 to the metal SAs located at the vast gas-solid reaction interfaces within the interconnected MOF pores
Following similar optimization strategy, the Pd1/ A-aUiO membranes can convert humid O2 to H2O2 with an activity of 10.4 mmol gcat–1 h–1 under visible light, which is more than 73-fold higher than that showed by the PdNPs/A-aUiO (0.14 mmol gcat–1 h–1) powders, verifying the wide applicability of our catalyst and reaction interface designs

Summary

Introduction

The demand for sustainable energy has motivated the development of artificial photosynthesis. The hierarchical channels of the PTFE films (Fig. 1g) and the interconnected pores of the SA/AaUiO particles naturally resembled the stomata of green leaves, facilitating the direct diffusion of gas molecules and the collision of them onto the open metal SA catalytic centers within the pores and channels of MOFs. Photocatalytic CO2 reduction reaction (CO2RR).

Results

Conclusion