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 −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 −1 ) than IrO 2 (78 mV dec −1 ) and exhibit Tafel slope of 131 mV dec −1 (HER) which is near to Pt (90 mV dec −1 ). Turnover frequency (TOF) was estimated as 0.22 s −1 (OER) and 0.26 s −1 (HER) was found to be 5 and 10 times higher than IrO 2 catalyst (0.040 s −1 ) and Pt/C catalyst (0.025 s −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.