Hierarchical FTO/PPy/ACo2O4 (A: Mn or Ni) with stacks spinel structure as superb photoanodes for photoelectrochemical water splitting

Abstract

Herein, the manganese (Mn) and nickel (Ni) doped cobalt oxide (Co3O4) with stacks spinel structure were incorporated on the polypyrrole (PPy)- coated Fluorine-doped tin oxide (FTO) glasses to improve oxygen evolution reaction (OER) efficiencies in PEC water splitting. We designed such a heterostructure configuration as an ideal model to understand the impact of the.MnCo2O4 and NiCo2O4 on the photoelectrocatalytic performances. Results showed that the FTO/PPy/NiCo2O4 possess superior photocurrent density (11.37 mA cm−2) compared to the FTO/PPy/Co3O4 (7.26 mA cm−2), and FTO/PPy/MnCo2O4 (9.16 mA cm−2) at 1.23 V vs. reverse hydrogen electrode (RHE). Moreover, the electrochemical surface area (ECSA) of the FTO/PPy/NiCo2O4 was obtained 1.4 and 1.8-folds higher than those considered for the FTO/PPy/MnCo2O4 and FTO/PPy/Co3O4, respectively. Specific spinel configuration of NiCo2O4 on PPy films provided the highest ECSA to access the carrier charge and their contribution in the redox reaction. The highest value of the O2 (5.256 μmol. h−1) was exuded from the surface of the FTO/PPy/NiCo2O4 by 2.5 and 1.8 orders of magnitude compared to those estimated for FTO/PPy/Co3O4, FTO/PPy/MnCo2O4.