Polyaniline Films as Electrochemical-Proton Pump for Acidification of Thin Layer Samples

Here, we provide the first experimental evidence
of proton release from polyaniline (PANI) films subjected to
anodic potentials at environmental pHs. We conducted an
extensive characterization of unpolarized/polarized PANI
filmssynthesized by traditional sequential voltammetric
scanningby using spectroelectrochemistry, synchrotron radi-
ation-X-ray photoelectron spectroscopy, near edge X-ray
absorption fine structure, and potentiometric pH sensing in
the vicinity of the PANI layer. This new insight enables the
utilization of PANI as a proton pump, which is actively tuned
through an electrochemical pulse, so as to controllably acidify
well-confined thin layer samples. Furthermore, we demonstrate
the analytical significance of this system by measuring the
alkalinity of artificial and natural water samples by using two faced planar PANI electrodes, one working as a proton source and the other one as pH electrode. Finally, the impact of this approach is 2-fold: (i) all-solid-state electrode materials may be used with devisible consequences in miniaturized and implementable submersible probes, and (ii) rapid determination of alkalinity as compared to traditional approaches together with a versatility in pH adjustment in any kind of sample, among other applications.