Green synthesis of fusiform-shaped Fe-PANI as a phenomenal dual electrocatalyst for overall water splitting and assessment of its sustainability standards

Abstract

Development of eco-friendly dual electrocatalysts for the oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) is gaining importance for renewable energy generation. In this study, green-synthesized Fe-PANI is reported as an efficient bifunctional electrocatalyst for the HER and OER processes. Fe-PANI/NF exhibits a lower overpotential (η) of 261 mV (OER) and 155 mV (HER) at 10 mA cm⁻² than commercial IrO₂ (341 mV) and near to that of Pt (36 mV), and a smaller Tafel slope (OER: 100 mV dec⁻¹/IrO₂ 125 mV dec⁻¹; HER: 120 mV dec⁻¹/Pt 74 mV dec⁻¹). The turnover frequency (TOF) of Fe-PANI (OER: 0.0673 s⁻¹/IrO₂ 0.0179 s⁻¹; HER: 0.022 s⁻¹/Pt 0.10 s⁻¹) was found to be higher than that of IrO₂ and near to that of Pt. For solar water electrolysis, Fe-PANI/NF exhibits overpotential of 411 mV and a durability over 100 h with 4.1% potential loss (1 M KOH). As a non-precious electrolyzer, Fe-PANI combined with a solar cell produces H₂ gas under sunlight. This methodology suggests that the green-synthesized Fe-PANI electrolyzer outperforms precious electrocatalysts. Hence, cost-effective large-scale H₂ production without an artificial current may be possible with a commercial solar cell. Furthermore, the environmental impact of Fe-PANI was evaluated by examining the significant sustainability metrics and socio-economic parameters.