Greenly Reduced CoFe‐PBA/Nickel Foam: A Robust Dual Electrocatalyst for Solar‐Driven Alkaline Water Electrolysis with a Low Cell Voltage

Abstract

Development of eco-friendly efficient dual electrocatalyst for oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) gaining increased attention for renewable energy production. Here, the greenly synthesized rCoFe-PBA was established as durable and effective bifunctional electrocatalyst for HER and OER process. The rCoFe-PBA coated Nickel foam electrode exhibit overpotential of 311 mV (OER) and 100 mV (HER) @ 10 mA cm À 2 significantly lower than commercial IrO 2 (381 mV) and near to Pt/C (36 mV). The rCoFe-PBA show smaller Tafel slope (OER: 57 mV dec À 1 ) than IrO 2 (78 mV dec À 1 ) and exhibit Tafel slope of 131 mV dec À 1 (HER) which is near to Pt (90 mV dec À 1 ). Turnover frequency (TOF) was estimated as 0.22 s À 1 (OER) and 0.26 s À 1 (HER) was found to be 5 and 10 times higher than IrO 2 catalyst (0.040 s À 1 ) and Pt/C catalyst (0.025 s À 1 ), respectively. For solar water electrolysis, rCoFe-PBA/NF shows overpotential of 411 mV and durability over 180 h in 1.0 m KOH (4.1 % potential loss). The combination of non-precious electrolyzer, rCoFe-PBA with commercial solar cell produced H 2 gas in alkaline water under sunlight. This methodology proves that the greenly synthesized rCoFe-PBA electrolyzer can outperform the precious electrocatalysts, implying that the cost-effective large scale H 2 production without artificial current is possible with commercial solar cells.

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

“…It can also provide a perfect pathway for evolution of O 2 and H 2 gas from the electrode surface without causing damage. 42,43 The most significant pore volumes of Fe-PANI electrocatalyst indicated that it is mainly macroporous, which is quite consistent with the effective OER and HER activity.…”

“…22). 43,60 The LSV curves indicate that the efficiency of Fe-PANI/NF// Fe-PANI/NF was superior to that of NF//NF (Fig. 22).…”

“…21). 43,[80][81][82][83][84][85] The semicircles in the Nyquist plot may be correlated to the charge-transfer resistance (R ct ) of the electrodes (Fe-PANI/NF-3.0 O) and NF (À10.4 O). Owing to a large ECSA, the R ct Fe-PANI/NF (3.0) was three times lower than that of NF (10.4).…”

“…The increased active sites may be responsible for the excellent OER/HER performance of Fe-PANI/NF. 42,43 Based on the above exceptional OER and HER performances, Fe-PANI/NF should be a robust bifunctional material for water splitting (1 M KOH: 1.0-2.0 V), with Fe-PANI/NF serving as both the anode and cathode [Fe-PANI/NF//Fe-PANI/ NF], compared with NF//NF, which was also constructed for comparison (Fig. 22).…”

Regulated Bimetal-Doped Polyaniline: Amorphous-Crumple-Structured Viable Electrocatalyst for an Efficient Oxygen Evolution Reaction

“…The electrochemical water splitting into H 2 and O 2 has been trusted as one of the propitious approaches to obtain spotless fuel from renewable energy sources . However, the huge process of electrochemical water splitting was mostly impeded by the slow anodic reaction [oxygen evolution reaction (OER)], where O–H bond dissociation with subsequent O–O bond making has been involved. ,− A suitable OER catalyst can address these difficulties by combining numerous proton and electron transfer for oxygen evolution at a low overpotential (η). − Most widely used ruthenium oxide (RuO 2 ) and iridium oxide (IrO 2 ) are the best OER catalysts; nevertheless, they are scarce and expensive. , Hence, alternative OER catalysts from 3d transition metals (Fe, Co, Ni, and Mn), mixed metal oxides (hydroxides), perovskites, phosphates, borides, chalcogenides, and molecular catalysts have been investigated. ,− However, still significant development is required to reduce the price of the catalyst with improved OER activity and stability. Bimetal oxides/hydroxides are one of the materials for high-performance electrodes along with several oxidation states because of the synergistic interaction between both metals with multivalent transitions in the quick Faraday reactions. , In the midst of various bimetal oxides/hydroxides, Co–Ni hydroxide has attracted attention as a result of the higher efficiency, good theoretical capacitance, and cooperative effect of Co and Ni .…”