Nickel cobalt selenide as a nano-moss electrocatalyst for detection of gaseous hydrogen peroxide

Nanoparticles composed specifically of transition metals have demonstrated significant potential not only in electrocatalysis but also in electroanalysis. In this context, this work presents a comprehensive investigation into the electrocatalytic properties of NiCo₂Se₄ nanomaterials, specifically designed for hydrogen peroxide (H₂O₂) detection. The unique needle-like nano-moss morphology of NiCo₂Se₄, confirmed through scanning electron microscopy (SEM), scanning and transmission electron microscopy (STEM), and high-angle annular dark-field (HAADF) analysis, reveals a highly organized structure with a large surface area, critical for enhanced catalytic performance. XRD analysis further establishes the material's high crystallinity and purity. Electrochemical characterization using cyclic voltammetry (CV) demonstrated the electrocatalytic activity of NiCo₂Se₄ towards the reduction of H₂O₂ in both oxygenated and deoxygenated conditions. The study identified that H₂O₂ disproportionation leads to oxygen generation at the electrode surface, which significantly enhances the reduction process. Tafel analysis showed notable enhancement of the electrode kinetics due to the catalyst's presence, affirming its efficacy in facilitating electron transfer. The influence of polyacrylic acid (PAA), used as a gas adsorbent, was also explored, confirming that while PAA slightly hinders diffusional mass transfer, it does not interfere with the overall catalytic process. Further investigation into the mechanistic aspects of the H₂O₂ reduction suggested a complex reaction pathway, likely involving a C_hetE mechanism combined with electrocatalysis of the second kind. This process is strongly influenced by the interplay between chemical disproportionation and electrode reactions, with oxygen acting as a redox catalyst. Finally, the practical application of NiCo₂Se₄-modified screen-printed electrodes (SPE) for gas-phase detection of H₂O₂ was explored. The sensor demonstrated the capability to detect gaseous H₂O₂, providing valuable insights into its potential use for environmental monitoring and industrial safety applications.