Ta2O5-incorporated in photoinduced electrocatalyst of TiO2-RuO2 decorated by PPy-NrGO nanocomposite for boosting overall water splitting

In the current work, the heterostructures highly PEC activity photoelectrodes composed of mixed metal oxides (TiO₂-RuO₂-Ta₂O₅ (TRT)), polypyrrole- N doped reduced graphene oxide (PPy-NrGO) were prepared by electrodeposition of PPy-NrGO films on the TRT- coated titanium (Ti) plates as substrates. The TRT coatings were deposited on Ti plates via the sol-gel technique. The effects of the Ta₂O₅ molar ratios were followed using physical and PEC measurements. Morphology studies showed that the surface structure of photoelectrodes alters remarkably by changing the Ta₂O₅ content in the mixture of metal oxides. TRT/PPy-NrGO photoelectrodes indicated to have a decreasing impact on the charge transfer resistance at the photoelectrode/electrolyte interfaces. The overall PEC water splitting performances of photoelectrodes were compared by measuring photocurrent density at 0 and 1.23 V vs. RHE, Tafel slopes, charge carrier density, stability, hydrogen evaluation reaction (HER) and oxygen evaluation reaction (OER) efficiencies. The highest HER (43.68% at −0.4 V) and OER (17.51% at 0.45 V) efficiencies were obtained in photoelectrodes comprising of 20 mol% Ta₂O₅ which possessed charge carrier density (5.9 × 10¹⁸) of about 1.7 times higher than that considered for TRT (0%)/PPy-NrGO with no Ta₂O₅ in the mixture of metal oxides.