Ultramicrosensors based on transition metal hexacyanoferrates for scanning electrochemical microscopy

Abstract

SummaryWe report here a way for improving the stability of ultramicroelectrodes (UME) based on hexacyanoferrate-modified metals for the detection of hydrogen peroxide. The most stable sensors were obtained by electrochemical deposition of six layers of hexacyanoferrates (HCF), more specifically, an alternating pattern of three layers of Prussian Blue and three layers of Ni–HCF. The microelectrodes modified with mixed layers were continuously monitored in 1 mM hydrogen peroxide and proved to be stable for more than 5 h under these conditions. The mixed layer microelectrodes exhibited a stability which is five times as high as the stability of conventional Prussian Blue-modified UMEs. The sensitivity of the mixed layer sensor was 0.32 A·M−1·cm−2, and the detection limit was 10 µM. The mixed layer-based UMEs were used as sensors in scanning electrochemical microscopy (SECM) experiments for imaging of hydrogen peroxide evolution.

Polymeric carbon nitride-based photocathodes for visible light-driven selective reduction of oxygen to hydrogen peroxide

“…However, the key question to be addressed was whether H2O2 can be detected as a product of the photoelectrocatalytic conversion. Since the molar concentrations of H2O2 accumulated in our cells were below the detection limit of the conventional colorimetric H2O2 determination using a reaction with titanium peroxo-complex, we measured the H2O2 evolution in-situ using amperometric microsensors [55][56][57]. To this end, we used H2O2 microelectrodes (diameter of 25 m) modified with Prussian blue (PB), as an effective electrocatalyst for H2O2 reduction, positioned approx.…”

“…Electrochemical deposition of PB on Pt microelectrodes (diam. 25 µm) was carried out according to previously published procedures [55][56][57]. In brief, four cycles in a potential range of 0.4 and 0.75 V vs. Ag/AgCl at a scan rate of 0.02 V/s were applied in a freshly prepared solution of 1.25 mM K3[Fe(CN)6] and 1.25 mM FeCl3 in 0.1 M HCl / 0.1 M KCl solution.…”

Operando Scanning Electrochemical Probe Microscopy during Electrocatalysis

“…Operando SECM operated in the SG-TC mode was employed to investigate substrate-generated H 2 O 2 by using a highly stable and selective ultramicrosensor (made of Prussian Blue modified with films of iron and nickel hexacyanoferrates) as a tip. A Au surface was biased to generate H 2 O 2 while the selective tip was employed for imaging the distribution of H 2 O 2 . The RC and SG-TC modes were also applied to investigate the electrochemical activities of various AuPd compositions deposited onto ITO toward H 2 O 2 and FcMeOH + reduction reactions .…”

“…A Au surface was biased to generate H 2 O 2 while the selective tip was employed for imaging the distribution of H 2 O 2 . 546 The RC and SG-TC modes were also applied to investigate the electrochemical activities of various AuPd compositions deposited onto ITO toward H 2 O 2 and FcMeOH + reduction reactions. 547 Tomlinson et al reported the first use of electrochemical imaging to identify the defect and defect-free areas in single crystal boron-doped diamond (BDD) electrodes.…”

Physicochemical Characteristics of Polypyrrole/(Glucose oxidase)/(Prussian Blue)‐based Biosensor Modified with Ni‐ and Co‐Hexacyanoferrates

“…Besides Prussian Blue (PB), which is indeed ferric hexacyanoferrate, deposits of different metal hexacyanoferrates (such as copper (II), cobalt (II), nickel (II), etc.) potentially can be also used as an electrocatalytic properties promoting material in development of chemical sensors and biosensors . However, the mechanism of hydrogen peroxide reduction catalysis by transition metals hexacyanoferrates is not discovered yet .…”