Detection of hydrogen peroxide produced at a liquid/liquid interface using scanning electrochemical microscopy

Abstract

a b s t r a c tScanning electrochemical microscopy (SECM) was used to monitor in situ hydrogen peroxide (H 2 O 2 ) produced at a polarized water/1,2-dichloroethane (DCE) interface. The water/DCE interface was formed between a DCE droplet containing decamethylferrocene (DMFc) supported on a solid electrode and an acidic aqueous solution. H 2 O 2 was generated by reducing oxygen with DMFc at the water/DCE interface, and was detected with a SECM tip positioned in the vicinity of the interface using a substrate generation/ tip collection mode. This work shows unambiguously how the H 2 O 2 generation depends on the polarization of the liquid/liquid interface, and how proton-coupled electron transfer reactions can be controlled at liquid/liquid interfaces.

Oxygen reduction by decamethylferrocene at liquid/liquid interfaces catalyzed by dodecylaniline

“…In aerobic conditions, the generation of hydrogen peroxide (H 2 O 2 ) has been verified by redox titration with sodium iodide [7] and scanning electrochemical microscopy [13]. Quantitative analysis of the reaction products after a two-phase reaction controlled by a common ion, as reported previously, the yield of H 2 O 2 with respect to the amount of DMFc + is about 38% [7].…”

“…Fig. 1b, Signal I is independent of the presence of oxygen and of subsequent chemical reactions that were previously shown to yield H 2 under anaerobic conditions [17] and H 2 O 2 in aerated solutions [7,13]. Indeed, the two curves are identical if the offset current of Signal II is subtracted.…”

“…Oxygen reduction at the ITIES has been so far studied by using various electron donors, decamethylferrocene (DMFc) [6][7][8][9], reduced flavin mononucleotide (FMN) [10], tetrachlorohydroquinone (CQH 2 ) [11] and fullerene monoanion (C À 60 ) [12]. In the case of DMFc, it has been shown that oxygen reduction at the polarized water/DCE interface produces decamethylferrocenium (DMFc + ) and hydrogen peroxide (H 2 O 2 ), on the basis of two-phase reactions [7] and in situ detection of H 2 O 2 using scanning electrochemical microscopy [13]. The catalytic effect of various porphyrin compounds, such as cobalt tetraphenylporphyrin [9,14], cobalt porphine [15] and free base tetraphenylporphyrin [16] and electrodeposited platinum particles [8], on the oxygen reduction by DMFc at the water/DCE interface has also been investigated.…”

Artificial Photosynthesis at Soft Interfaces

“…Here, we do not use this technique to record SECM images of the interfacial reactivity as the interface is often not structured in the absence of adsorbed films but we use this methodology to measure the kinetics of the heterogeneous recycling reactions by recording approach curves. [9] Finally, we have developed methods to study adsorbed nanoparticles at ITIES. Indeed, solid nanoparticles such as quantum dots or metallic nanoparticles such as platinum or gold nanoparticles adsorb at liquid-liquid interfaces due to a compromise between line tensions and interfacial tensions.…”

Rapid optimization of a lactate biosensor design using soft probes scanning electrochemical microscopy

“…The detection of H 2 O 2 by SECM probes has been already studied by using bare Pt ultramicroelectrodes or Prussian Blue modified ultramicroelectrodes supported on complex structures such as Au/Pt/C [27,48,36]. Soft stylus probes offer a more stable and a simpler fabrication protocol of H 2 O 2 microsensors based on Prussian Blue catalytic films for SECM studies.…”