Boosting Surface Reconstruction for the Oxygen Evolution Reaction: A Combined Effect of Heteroatom Incorporation and Anion Etching in Cobalt Silicate Precatalyst. Issue 5 (28th December 2021)

• Record Type: Journal Article
• Authors: Sarkar, Debashrita; Ganguli, Sagar; Mondal, Ayan; Mahalingam, Venkataramanan
• Is Part Of: ChemElectroChem. Volume 9:Issue 5(2022)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2021-12-28
• Subjects: oxygen evolution reaction -- anion etching -- silicates -- surface reconstruction -- cobalt; Electrochemistry -- Periodicals; 541.37
• DOI: 10.1002/celc.202101140
• Languages: English
• ISSNs: 2196-0216

Abstract

Abstract: Electrochemical water splitting is one of the most desirable techniques for combatting the global challenge of sustainable fuel generation. The generation of highly active electrocatalysts for efficient oxygen evolution reaction (OER) requires the rational design of a precatalyst that can enhance the number density of the active catalyst generated during water splitting. In this work, we report sulfurincorporated iron‐doped cobalt silicate (CoFeSiO−S) nanoparticles, which exhibit a unique ability to show gradual improvement in the electrocatalytic behavior with time. The precatalyst could reach a low overpotential of 267±6 mV at benchmark current density of 10 mA/cm 2 and 300 mV at 100 mA/cm 2 current density after applying chronopotentiometry for 30 h. The exceptional OER performance is further evidence by a low Tafel slope of 37.0±0.5 mV/dec with a very high TOF value of 1.05 s −1 . This improved activity is attributed to 1) facilitation of Co 2+ /Co 3+ by Fe doping, 2) faster catalyst activation due to lower metal‐sulfur bond energy compared to metal‐oxygen bond energy, 3) higher pore diameter that enables faster diffusion of reactants and products, 4) lower charge transfer resistance of sulfur incorporated iron‐doped cobalt phyllosilicate than pristine, and 5) silicate anion etching in the electrolyte. This work establishes a fundamental understanding of the surface reconstruction occurring during the OER process where silicates are employed as precatalyst. Abstract : Beneficial transformation : Sulfur incorporated iron‐doped cobalt silicate is drop‐casted onto a carbon paper electrode to function as an oxygen evolution catalyst. The electrocatalyst undergoes silicate anion etching during alkaline water splitting. An abundance of cobalt active centers are exposed on the electrode surface, which were previously embedded in the bulk, leading to higher accessibility of the electrolyte to the active centers. Surface reconstruction takes place causing the silicate surface to transform into the corresponding oxyhydroxide.