Free‐Sustaining Three‐Dimensional S235 Steel‐Based Porous Electrocatalyst for Highly Efficient and Durable Oxygen Evolution

Abstract

A novel oxygen evolution reaction (OER) catalyst (3 D S235-P steel) based on a steel S235 substrate was successfully prepared by facile one-step surface modification. The standard carbon-manganese steel was phosphorized superficially, which led to the formation of a unique 3 D interconnected nanoporous surface with a high specific area that facilitated the electrocatalytically initiated oxygen evolution reaction. The prepared 3 D S235-P steel exhibited enhanced electrocatalytic OER activities in the alkaline regime, as confirmed by a low overpotential (326 mV at a 10 mA cm ) and a small Tafel slope of 68.7 mV dec . Moreover, the catalyst was found to be stable under long-term usage conditions, functioning as an oxygen-evolving electrode at pH 13, as evidenced by the sufficient charge-to-oxygen conversion rate (faradaic efficiency: 82.11 and 88.34 % at 10 and 5 mA cm , respectively). In addition, it turned out that the chosen surface modification delivered steel S235 as an OER electrocatalyst that was stable under neutral pH conditions. Our investigation revealed that the high catalytic activities likely stemmed from the generated Fe/(Mn) hydroxide/oxohydroxides generated during the OER process. Phosphorization treatment therefore not only is an efficient way to optimize the electrocatalytic performance of standard carbon-manganese steel but also enables for the development of low-costing and abundant steels in the field of energy conversion.

From Bad Electrochemical Practices to an Environmental and Waste Reducing Approach for the Generation of Active Hydrogen Evolving Electrodes

“…An unusual high double‐layer capacitance was determined for all samples (Ni42: 6.8 mF cm −2 , Ni42Pt:2.7 mF cm −2 , Ni42SoPt: 4.35 mF cm −2 ). Values in the mF cm 2 range were also obtained for surface modified S235 steel as reported by us in one of our previous contributions . However, phosphorized S235 steel exhibited substantially higher double‐layer capacitance values (46.1 mF cm −2 ) than untreated S235 steel (0.2 mF cm −2 ), which was very likely caused by the enormous increase of the porosity that occurs to steel S235 when phosphorized at high temperatures.…”

“…Values in the mF cm 2 range were also obtained for surface modified S235 steel as reported by us in one of our previous contributions . However, phosphorized S235 steel exhibited substantially higher double‐layer capacitance values (46.1 mF cm −2 ) than untreated S235 steel (0.2 mF cm −2 ), which was very likely caused by the enormous increase of the porosity that occurs to steel S235 when phosphorized at high temperatures. Thus, we stipulate that the double layer capacitance values derived from samples Ni42, Ni42Pt, and Ni42SoPt, which are of the same order of magnitude, basically result from comparable roughness of samples Ni42, Ni42Pt, and Ni42SoPt; as confirmed by AFM and SEM techniques (Figure ).…”

From Bad Electrochemical Practices to an Environmental and Waste Reducing Approach for the Generation of Active Hydrogen Evolving Electrodes

“…Values in the mF cm 2 range were also obtained for surface modified S235 steel as reported by us in one of our previous contributions. [41] However, phosphorized S235 steel exhibited substantially higher double-layer capacitance values (46.1 mF cm À2 ) than untreated S235 steel (0.2 mF cm À2 ), [41] which was very likely caused by the enormous increase of the porosity that occurs to steel S235 when phosphorized at high temperatures. Thus, we stipulate that the double layer capacitance values derived from samples Ni42, Ni42Pt, and Ni42SoPt, which are of the same order of magnitude, basically result from comparable roughness of samples Ni42, Ni42Pt, and Ni42SoPt; as confirmed by AFM and SEM techniques ( Figure 6).…”

Electrochemical Cathodic Treatment of Mild Steel as a Host for Ni(OH)2 Catalyst for Oxygen Evolution Reaction in Alkaline Media

“…The smaller Tafel slope of C MS Ni(OH) 2 (i. e., 66 mV dec À 1 ) than others and closer to the recent report of 3D S235-P steel (68.7 mV dec À 1 ), oxidise mild steel S235 (58.5-66 mV dec À 1 in 0.5, 1, 2, and 5 M KOH) and Tin plated mild steel (60-68 mV dec À 1 ) indicate the improved kinetics behind OER and chemical step of OH À ions interaction with C MS Ni(OH) 2 is the rate determining step. [16][17][18] To further emphasize the catalytic characteristics, EIS study was utilized to describe the solution induced resistance (R s ) at the electrode/catalysts/electrolyte interface and charge transfer resistance (R ct ) in the OER condition. [1,8,10,[37][38][39] Figure 7(a and b) depicts the EIS Nyquist and Bode plots measured at 300 mV of η in 1 M KOH.…”

“…[1,16] Han et al used threedimensional phosphorized S235 steel in alkaline media. [17] Devi et al employed Sn plated steel as OER catalyst. [18] Mitra et al used Ni modified at 200 and 400°C steel like iron substrate obtained by sintering 1 : 1 mixture of carbonyl iron powder and ammonium bicarbonate at 850°C.…”