Formation and electroanalytical performance of polyaniline–palladium nanocomposites obtained via Layer-by-Layer adsorption and electroless metal deposition

The Layer-by-Layer (LbL) adsorption technique is used to produce thin composite layers consisting of polyaniline (PANI) and Pd particles in two different ways: (i) multistep adsorption of PANI and pre-synthesized Pd nanoparticles (NPs) and (ii) multistep adsorption of PANI and polysterene sulfonate (PSS) followed by electroless deposition of palladium particles (Pdeless). The formation of both types of composite layers is characterized by electrochemical and microgravimetric measurements.Electrochemical measurements for hydrogen peroxide reduction are carried out at neutral pH under voltammetric and amperometric conditions. It is established that the PANI–Pd NPs composites show a sensitive voltammetric response for H2O2 reduction in the 40–300 μM concentration range whereas the (PANI–PSS)Pdeless composites have high intrinsic electroactivity that masks the H2O2 reductive response. The amperometric data show high sensitivity for both types of composites: PANI–Pd NPs and (PANI–PSS)Pdeless (with Pd incorporated in several electroless deposition steps). For the PANI–Pd NPs material the concentration range of linear response is 10–700 μM and the limit of detection 2.6 μM. The obtained non-enzymatic electrocatalytic materials are suitable for monitoring the levels of H2O2 in drinking and waste waters.