Core-Shell Iron-Nickel Hexacyanoferrate Nanoparticle-Based Sensors for Hydrogen Peroxide Scavenging Activity

To access hydrogen peroxide scavenging activity, we propose a sensor based on core-shell iron-nickel hexacyanoferrate nanoparticles. On the one hand, the sensor preparation procedure is simple: syringing the nanoparticles suspension with subsequent annealing. On the other hand, the sensor demonstrates a stable response to 0.05 mM of H2O2 within one hour, which is sufficient for the evaluation of antioxidant activity (AO). The analytical performance characteristics of the sensor (0.5–0.6 A M−1 cm−2, detection limit 1.5 × 10−7 M and linear dynamic range 1–1000 µM) are leads to advantages over the sensor based on Prussian Blue films. The pseudo-first-order constant of hydrogen peroxide scavenging was chosen as a characteristic value of AO. The latter for trolox (standard antioxidant) was found to be linearly dependent on its concentration, thus allowing for the evaluation of antioxidant activity in trolox equivalents. The approach was validated by analyzing real beverage samples. Both the simplicity of sensor preparation and an expressiveness of analytical procedure would obviously provide a wide use of the proposed approach in the evaluation of antioxidant activity.

Environmentally Benign Formation of Nickel Hexacyanoferrate-Derived Mesoframes for Heterogeneous Catalysis

The tetramethylammonium hydroxide (TMAH)-controlled alkaline etching of nickel hexacyanoferrate (NiHCF) mesocrystals is explored. The alkaline etching enables the formation of hollow framework structures with an increased surface area, the exposure of active Ni and Fe sites and the retention of morphology. The ambient reaction conditions enable the establishment of a sustainable production. Our work reveals novel perspectives on the eco-friendly synthesis of hollow and colloidal superstructures for the efficient degradation of the organic contaminants rhodamine-B and bisphenol-A. In the case of peroxomonosulfate (PMS)-mediated bisphenol-A degradation, the rate constant of the etched mesoframes was 10,000 times higher indicating their significant catalytic activity.

Comparing electrochemical analysis and particle induced X-ray emission measurements of Prussian Blue Analogue deposits

Prussian Blue Analogues are of major interest for their use in alternative battery technologies due to their charge storing ability with a long life cycle. In this work the Prussian Blue Analogue nickel hexacyanoferrate (Ni-HCF) was produced using an all electrochemical method. Creating charge storing materials with electrochemical processes provides a new approach to the development of battery-like materials. These methods have not been commonly employed because the charge storing material yield is not directly known. The charge storage of the Ni-HCF was characterized with two different methods which provided a measure of the electrochemically active Fe present. These were then compared with the Particle Induced X-ray Emission (PIXE) method which measured the total amount of Fe present. By comparing the electrochemical measurement of active Fe to the total Fe as measured by PIXE, the percentage of material that is active in the charge storage was determined. This enables an independent calculation of the specific charge capacity of the material for comparison to other battery technologies.