Adapting Early Transition Metal and Nonmetallic Dopants on CoFe Oxyhydroxides for Enhanced Alkaline and Neutral pH Saline Water Oxidation
Ahmed Badreldin, Ahmed Nabeeh, Ebtihal Youssef, Noor Mubarak, Hania Mohamed Gaber Hassan Elsayed, Rana Mohsen, Fatma Ahmed, Wubulikasimu Yiming, Khaled Elsaid, Ahmed Abdel‐Wahab
Abstract
The development of earth-abundant electrocatalysts that are highly active and stable in saline electrolytes is a prerequisite toward the commercial realization of seawater electrolysis. In this work, we synthesized S,B-(CoFeCr) and S,B-(CoFeV) oxyhydroxides using a facile solution combustion synthesis (SCS) method for Co3O4 production followed by a simple wet chemistry doping strategy in an alkaline environment. Dopants of early transition metals (i.e., Cr and V) and nonmetals (i.e., S and B) were employed to synergistically enhance activity through surface modulation and to improve hydrophilicity toward water oxidation in neutral and near-neutral pH saline electrolyte. We performed an array of characterization techniques including high-resolution transmission electron microscopy (HRTEM), field-emission scanning electron microscopy (FESEM), energy-dispersive spectroscopy (EDS), Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS) (pre- and post-OER) to characterize intrinsic properties of the developed catalysts. The as-prepared S,B-(CoFeCr)OOH and S,B-(CoFeV)OOH electrocatalysts required low oxygen evolution reaction (OER) overpotentials of 174 and 242 mV to achieve a current density of 10 mA cm–2 with low Tafel slopes of 45.8 and 52.3 mV dec–1, respectively, in an alkaline saline (1 M KOH + 0.5 M NaCl) electrolyte. Chronopotentiometric stability tests indicated a stable performance in a neutral pH saline environment for prolonged times with a curbed chlorine evolution reaction.