Green Reduction of Cobalt Ferrocyanide with Excellent Electrocatalytic Activity toward the Oxygen Evolution Reaction

Abstract

The development of earth-friendly efficient electrocatalysts for the oxygen evolution reaction (OER) becomes crucial for renewable energy production. In this work, green synthesized reduced cobalt ferrocyanide at different time intervals (RCFC-t) was demonstrated as an effective and long-lasting electrocatalyst for the OER process. The RCFC-10 loaded glassy carbon electrode runs at an overpotential of 321 mV (1.55 V) at 10 mA cm–2, and a lower overpotential of 291 mV exhibited by the optimal RCFC-10/nickel foam was almost comparable to the benchmark catalyst, such as IrO2. This newborn RCFC-10 shows excellent OER performance and durability over 250 h with 4.1% potential loss in alkaline medium. At 1.58 V, the solar-driven water electrolysis demonstration supports the efficiency of a newborn electrocatalyst in solar-to-hydrogen conversion. These research findings confirm that low-cost greener synthesized RCFC-10/NF can be used for large-scale hydrogen generation.

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

“…The infrared spectra of electrocatalysts, CoFe‐PBA and rCoFe‐PBA was displayed in Figure 1. The frequency of 3500–3000 cm −1 attributed to OH confirm moisture in CoFe‐PBA and rCoFe‐PBA [25,36] . The most intensified cyano stretching frequency at 2081 cm −1 for CoFe‐PBA was shifted to 2070 cm −1 for rCoFe‐PBA hence, C and N may be present as Co II ‐CN‐Fe III form in CoFe‐PBA and rCoFe‐PBA [37–43] .…”

“…The frequency of 3500-3000 cm À 1 attributed to OH confirm moisture in CoFe-PBA and rCoFe-PBA. [25,36] The most intensified cyano stretching frequency at 2081 cm À 1 for CoFe-PBA was shifted to 2070 cm À 1 for rCoFe-PBA hence, C and N may be present as Co II -CN-Fe III form in CoFe-PBA and rCoFe-PBA. [37][38][39][40][41][42][43] The blue shifted cyanide stretching from CoFe-PBA to rCoFe-PBA confirmed the mushroom green reduction.…”

“…The X‐ray photoelectron spectroscopy (XPS) was used to find different electronic states of Co, Fe, C, N and O in rCoFe‐PBA (Figure 7). [25] The deconvoluted Co 2p spectrum of rCoFe‐PBA exhibit peaks at 782.4 eV (Co 2p 3/2 ) and 797.5 eV (Co 2p 1/2 ) belongs to Co 2+ at octahedral sites and their satellite peaks was appeared at 784.7 and 803.3 eV, respectively [54,55] . The deconvoluted Fe 2p 3/2 spectrum show peaks at 709.8 eV ([Fe(CN) 6 ] 3− ) and 708.2 eV ( [Fe(CN) 6 ] 4− ) and other peaks at 723.5 eV and 721.2 eV may attributed to Fe 3+ (Figure 7).…”

“…The amount of hydrogen generated was found to be 6.53 mmol h −1 cm −2 during water electrolysis (SI. S1) [25,81,82] . Hence, solar‐assisted water splitting set‐up established in this study could be applied for cost‐effective H 2 production in water‐splitting industry.…”

“…[23] Though robust CoFe-based Prussian blue analogues (CoFe-PBA) are highly stable with uniformly dispersed metal sites and having high porosity, nanomaterials reduction by hydrazine and sodium borohydride are toxic hence, it is necessary to optimize eco-friendly, green reducing agent for clean reduction of nanomaterials. [24][25][26][27][28][29][30][31][32][33] Hence it is planned to use mushroom extract, a non-toxic and mild reducing agent to synthesis rCoFe-PBA for first time. [34,35] Herein, we report greenly synthesized rCoFe-PBA/NF electrode employed as dual electrocatalyst for water splitting.…”