H₂O₂ Ratiometric Electrochemical Sensors Based on Nanospheres Derived from Ferrocence-Modified Covalent Organic Frameworks

Abstract

A uniform nanosphere derived from ferrocence-modified covalent-organic frameworks (COFETTA‑TPAL-Fc­(COOH)2) with 200 nm in diameter was prepared by dehydration condensation reaction between 4,4′,4′,4′- (ethane-1,1,2,2-tetrayl) tetraaniline and terephthalaldehyde in the presence of electroactive Fc­(COOH)2. The Fc­(COOH)2 was embedded into the layers of COFETTA‑TPAL to result in the formation of nanospheres, which increased the specific surface area of the available COFETTA‑TPAL to provide more active sites due to the increase in interlayer distance. The Fc­(COOH)2 could interact with H2O2 which might undergo self-disproportionation process to produce O2 and be reduced into H2O simultaneously, whereas the generated O2 was directly reduced into H2O by COFETTA‑TPAL. The reduction peak current of the generated O2 at −0.5 V (j –0.5 V) was gradually enhanced, whereas that of Fc­(COOH)2 around 0.45 V (j 0.45 V) was decreased with continuous adding of H2O2. Thus, the COFETTA‑TPAL-Fc­(COOH)2 nanospheres were used to fabricate a “on–off” nonenzymatic H2O2 ratiometric electrochemical sensor. The proposed “on–off” ratiometric electrochemical sensor showed good performance with a wide linear range of 1.1–500 μM, high sensitivity of 0.009 μM–1, and lower detection limit of 0.33 μM. The work would offer insights for design and preparation of electroactive COF and accelerate the practical application of COF in electroanalysis.

A Paper-Based Electrochemical Sensor Based on PtNP/COFTFPB−DHzDS@rGO for Sensitive Detection of Furazolidone

“…According to the N 2 adsorption and desorption isotherms ( Figure S1d ) of COF TFPB−DHzDs , the specific surface area of COF TFPB−DHzDs was about 153.76 m 2 g −1 , and the average pore size was about 1.9 nm. Its specific surface area was large, suggesting it could be used as an excellent support material [ 28 ].…”

Recent Progress of Covalent Organic Frameworks Applied in Electrochemical Sensors

“…Wang and co-workers prepared a ferrocene-modified COF (COF ETTA‑TPAL -Fc-(COOH) 2 ) by Schiff base reaction between 4,4′,4′,4′-(ethane-1,1,2,2-tetrayl) tetraaniline (ETTA) and terephthalaldehyde (TPAL) in the presence of electroactive Fc­(COOH) 2 (Figure ). The interlayer distance of COF ETTA‑TPAL was enlarged, and the active sites were increased by embedding Fc­(COOH) 2 into the layers of COF ETTA‑TPAL . Fc­(COOH) 2 can interact with H 2 O 2 to generate O 2 , while COF ETTA‑TPAL directly reduces the generated O 2 to H 2 O (Figure ).…”

Heterostructured hybrids of metal–organic frameworks (MOFs) and covalent–organic frameworks (COFs)

“…165,166 Recently, many biosensors based on diverse MOFs (Zr-MOF, Al-MOF, Fe-MOF, Zn-MOF, etc. ) 167 and COFs 168 have been developed for detecting diverse targets, such as small biomolecules (H 2 O 2 , dopamine, and ascorbic acid (AA)), 169 antibiotics, 170 biomarkers, 171 heavy metal ions, 172 proteins, 173 and living cancer cells, 174 via different determination techniques, including electrochemical methods, 175,176 fluorescence approaches, 170,177,178 electrochemiluminescence, 175 surface plasmon resonance, 179 colorimetric method, 180 microfluidic impedance 181 and chemiluminescence. 182 Among them, the electrochemical method is an efficient technique for the detection of biomolecules in the biological field.…”