Upconversion Luminescent Humidity Sensors Based on Lanthanide-Doped MOFs

Zhuo Wang,Hong Jiang,Jiabo Chen,Lining Sun,Guotao Sun,Yao Xie

doi:10.3390/chemosensors10020066

Zhuo Wang, Hong Jiang + Show 4 more

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https://doi.org/10.3390/chemosensors10020066

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Journal: Chemosensors	Publication Date: Feb 7, 2022
Citations: 8	License type: CC BY 4.0

Affiliation: Shanghai University, Hainan University

Abstract

Lanthanide-doped metal-organic frameworks (Y/Yb/Er-MOF) were synthesized by a low-cost solvothermal method. The obtained Y/Yb/Er-MOF shows the cooperative upconversion luminescence of Yb3+ and upconversion luminescence of Er3+ (Yb3+-sensitized) irradiated by a continuous wave 980 nm laser. In order to explore the potential application of Y/Yb/Er-MOF in relative humidity (RH) sensors, the RH responsiveness of Y/Yb/Er-MOF was investigated by measuring the intensity changes of upconversion luminescence. The Y/Yb/Er-MOF possesses two luminescence centers, in which Yb3+ forms emission at 500 nm through the cooperative luminescence effect, and Er3+ achieves 660 nm emission through excited state absorption and successive energy transfer from Yb3+. Hence, the ratio meter luminescence sensor for RH is constructed based on Y/Yb/Er-MOF. The results show that the response of Y/Yb/Er-MOF to RH presents a linear relationship in the range of 11–95%. The cycle stability of Y/Yb/Er-MOF responses to RH was investigated with the intensity changes of upconversion luminescence, and the recovery ratio was more than 93% each time. Therefore, the Y/Yb/Er-MOF is a humidity-sensitive material with great potential for applications such as humidity sensors.

Highlights

Publisher’s Note: MDPI stays neutralHumidity is a physical quantity that indicates the degree of air dryness
All chemical materials and characterizations used in this work are listed in the Supporting Information
Properties was characterized by scanning electron microscopy (SEM) and transmission electron microscopy (TEM), as shown in Figure 1a and

Summary

Introduction

Humidity is a physical quantity that indicates the degree of air dryness. The less water vapor in a certain air volume at a certain temperature, the drier the air; the more water vapor, the more humid. Humidity is often expressed by relative humidity (RH), comparative humidity, mixing ratio, saturation difference, and dew point. RH is the ratio percentage of the actual water vapor pressure in the air to the saturated water vapor pressure at the current temperature, which is the most common form of humidity. The RH of 50% air contains half as much water vapor as the saturation point at the same temperature. Air with an RH of 100% is saturated with water vapor. Water vapor in the air generally condenses out when the relative humidity exceeds 100%

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