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

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.