Polyelectrolyte‐Enhanced Electrochemical Sensing of Gaseous Hydrogen Peroxide With Copper(II)–Mediating Systems

Hydrogen peroxide (H 2 O 2 ) plays a crucial role in both biological and industrial applications; hence, there is a growing need to develop methods that enable reliable and efficient detection. While traditional techniques such as spectrophotometry and fluorescence provide high sensitivity, electrochemical methods offer rapid, cost‐effective, and real‐time monitoring capabilities. This study explores the role of polyelectrolytes as supporting electrolytes in enhancing electrochemical detection of hydrogen peroxide using copper(II)‐mediated electrocatalysis. Building upon our previous research utilizing polyacrylic acid (PAA), alternative polyelectrolytes, including poly(2‐acrylamido‐2‐methyl‐1‐propanesulfonic acid) (pAMPS) and poly(acrylamide‐co‐acrylic acid) (pAAmAA), were investigated. Cyclic and square‐wave voltammetry were employed to assess the impact of these polymers on the electrochemical performance. Results indicated that pAMPS strongly complexed Cu 2+ , reducing catalytic efficiency, whereas neutralized pAMPS improved Cu 2+ availability, enhancing H 2 O 2 reduction. Among all tested electrolytes, 1% pAAmAA demonstrated the highest sensitivity for direct H 2 O 2 reduction and was subsequently selected for the gas‐phase studies. Further optimization involved modifying pAMPS’ pH, revealing that pAMPS at pH 2 significantly enhanced overall catalytic activity. The combination of pAMPS and pAAmAA with Prussian blue‐modified screen‐printed electrodes enabled H 2 O 2 gas‐phase detection down to 1.8 × 10 −10 mol L −1 . These findings highlight the potential of polyelectrolyte‐based electrolytes for improving the sensitivity and selectivity of electrochemical hydrogen peroxide detection, particularly in gas‐phase applications.