Photoelectrocatalytic oxidation of ascorbic acid and electrocatalytic reduction of dioxygen by polyaniline films for renewable energy conversion

• PANI shows good linear spectral absorbance and/or photovoltaic responses to AA.
• PANI/CF exhibits a good linear potentiometric response to O2 flux rate.
• Visible light-driven AA/O2 fuel cell possesses high performance.

A honeycomb-structured polyaniline (PANI) film is used to simultaneously promote the photoelectrocatalytic oxidation of ascorbic acid (AA) and electrocatalytic reduction of dioxygen (O2). The in situ spectroelectrochemical evidences suggest that the PANI film controlled between − 0.20 and 0.70 V shows four transformable redox forms, among which emeraldine base (EB) and leucoemeraldine base (LEB) can mediate the oxidation of AA and the reduction of O2, respectively. The EB-based electrode exhibits good linear spectral absorbance and/or photovoltaic responses to AA between 0.01 and 1.0 mmol L− 1 with high sensitivity and good reproducibility. The LEB-based electrode shows a good linear potentiometric response to O2 permeation flux rate between 10 and 60 mL min− 1. Furthermore, the CdS nanoparticles and carbon felt (CF) are used to support the PANI film for the preparation of PANI/CdS anode and PANI/CF cathode. The assembled photoelectrochemical fuel cell driven by visible light shows an open-circuit photovoltage of 0.614 V, short-circuit photocurrent density of 125.55 μA cm− 2, maximum power density of 19.05 μW cm− 2 at 0.492 V, fill factor of 0.24 and photoenergy conversion efficiency of 10.58%. The present study provides a new approach for the utilization of renewable energy sources.

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