An experimental and theoretical approach to electrochemical sensing of hydrazine at silver and copper hexacyanoferrates electrodes

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• This work evaluates the electrocatalytic oxidation of hydrazine (HDZ) by silver (AgHCF) and copper (CuHCF) hexacyanoferrates-modified glassy carbon electrodes kinetically and analytically through experimental electrochemistry and theoretical approaches

• The materials were prepared by a two-step cyclic voltammetry (CV) routes

• The AgHCF and CuHCF-modified electrodes showed quasi-reversible characteristics driven by K+ diffusion and adsorption processes, respectively.

• The analyte exhibited irreversible electron transfer controlled by semi-infinite diffusion process for both Prussian blue analogs.

• Theoretical approaches showed that CuHCF material required lower energy (ΔEgap = 0.0397 eV) to promote an electron to the lowest unoccupied molecular orbital due to its cubic structural arrangement,

• justifying the better electrocatalytic results comparing to the hexagonal structure of the AgHCF material (ΔEgap = 0.0840 eV).

• Atomic details of the orbitals involved in HOMO→LUMO energy gap were investigated using density functional theory (DFT) calculations

• This work aims at the experimental and theoretical studies of HDZ electrocatalytic response of two electrochemically prepared PBA: AgHCF and CuHCF and promotes a discussion about what features are involved in this specific application.

• A peak current increasing starting at −0.3 V indicates the deposition of the metal particles through the reaction Cu2+(aq) + 2e− → Cu0(s)

• This phenomenon represents the potential where the nucleation of metallic species happens, called crossover potential

• The subsequent cycles also demonstrate the same property, which suggests that new nucleation sites are being created through the whole deposition.

• the CuHCF solid is a better oxidation agent than AgHCF.

• the energy required to promote electron between HOMO→LUMO orbitals is lower in CuHCF (0.0397 eV) than AgHCF (0.0840 eV)