Upconversion Luminescent Humidity Sensors Based on Lanthanide-Doped MOFs

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.

Transition metal and lanthanide modified MOF-808 for barcode design

“…Thus, the incorporation of cobalt cations has a significant stronger influence on the fluorescence of the material than iron cations. Many humidity sensors based on europium compounds have been observed to exhibit varying responses to humidity: while a decrease in fluorescence with increasing humidity is common, [29][30][31][32][33] there are also reports of materials showing the opposite tendency. 28,34 The persistence of fluorescence in the presence of increasing amounts of water molecules could be justified by an efficient reduction of the strong coupling of O-H vibrations on the water molecules coordinating to europium within the framework by host-guest O-H⋯O hydrogen bonding interactions.…”

Emerging Doped Metal–Organic Frameworks: Recent Progress in Synthesis, Applications, and First‐Principles Calculations

“…With the unique d-orbital electronic structure, lanthanide-doped MOFs have also received extensive attention. Sun et al [174] synthesized Y/Yb/Er-MOFs by the doping of lanthanide, which exhibited cooperative upconversion luminescence of Yb 3+ and upconversion luminescence of Er 3+ when excited with a continuous-wave 980 nm laser (Figure 9d,e), and could be used to construct a ratiometric luminescence sensor ) Rate performance at different current densities of Mn-MIL-100@S, MnNi-MIL-100@S, MnCo-MIL-100@S, MnZn-MIL-100@S, and MnPb-MIL-100@S. c) Cycle performance and coulombic efficiency at a current density of 0.1 C. Reproduced with permission. [96] Copyright 2021, Wiley-VCH.…”

“…Reproduced with permission. [ 174 ] Copyright 2022, MDPI (Basel, Switzerland). g) Schematic diagram of the construction process and application of AgNCs/BPQDs/MOF nanohybrids as a ratiometric fluorescence biosensor for visual detection of BAI.…”

“…f) Real-time response of the upconversion luminescence spectra (𝜆 ex = 980 nm, 1.5 W) of Y/Yb/Er-MOF with different relative humidity (RH) environments (11-95% RH). Reproduced with permission [174]. Copyright 2022, MDPI (Basel, Switzerland).…”

Humidity Sensors Based on Metal–Organic Frameworks

“…The linear detection range of the Eu−MOF−based sensor was 0–100% RH with excellent recycle ability (at least 7000 s). Wang et al [ 129 ] prepared an upconversion luminescent Ln−MOF (Y/Yb/Er−MOF). The water molecules absorb the energy transferred from Yb, thus quenching the upconversion luminescence of the Ln−MOF ( Figure 14 a).…”