A honeycomb-structured polyaniline (PANI) film is used to simultaneously promote the photoelectrocatalytic oxidation of ascorbic acid (AA) and electrocatalytic reduction of dioxygen (O-2). 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 O-2, 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 02 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 NA cm(-2), maximum power density of 19.05 mu W cm(-2) at 0.492 V, fill factor of 024 and photoenergy conversion efficiency of 10.58%. The present study provides a new approach for the utilization of renewable energy sources. (C) 2016 Elsevier B.V. All rights reserved.