An Acid-Resistant\nLanthanide Metal–Organic\nFramework Based on Tetraphenylethylene as an Electrochemical Nitrite\nSensor

Nitrite (NO<sub>2</sub><sup>–</sup>) is attracting\nincreasing\nattention due to its harmful effect on human health. Thus, it is highly\ndesirable to construct effective electrochemical sensors to detect\nthe presence of NO<sub>2</sub><sup>–</sup>. The majority of\nelectrochemical NO<sub>2</sub><sup>–</sup> detection is focused\non alkaline or neutral electrolyte solutions and is rarely reported\nunder acidic conditions. In this work, a tetraphenylethylene (TPE)-based\n2D lanthanide metal–organic framework (Ln-MOF), (Me<sub>2</sub>NH<sub>2</sub>)[Ho<sup>III</sup>(tcbpe-F)DMF]•DMF•H<sub>2</sub>O (<b>1</b>) (tcbpe-F = 4′,4‴,4″‴,4″″‴-(ethene-1,1,2,2-tetrayl)tetrakis(3-fluoro-[1,1′-biphenyl]-4-carboxylic\nacid, DMF = <i>N,N</i>-dimethylformamide)), has been successfully\nfabricated on carbon paper (<b>CP</b>) by an in situ hydrothermal\nmethod. As a NO<sub>2</sub><sup>–</sup> sensor, the fabricated <b>1</b> electrode exhibited excellent electrochemical performance\nin the H<sub>2</sub>SO<sub>4</sub> electrolyte (pH = 1) and offers\nhigh sensitivities of 1453.2 and 591.5 μA mM<sup>–1</sup> cm<sup>–2</sup>, with a wide linear detection range of 0.1\nμM to 9 M, a low detection limit of 60 nM, excellent specificity\neven in the presence of various analytes (metal ions, anions, and\norganic molecules) and real water samples, satisfactory stability,\nand reproducibility. This is the first report of TPE-based Ln-MOF\nas a NO<sub>2</sub><sup>–</sup> sensor, and furthermore, a\nplausible sensing mechanism is confirmed by experiments and theoretical\ncomputations.