Iron-induced 3D nanoporous iron-cobalt oxyhydroxide on carbon cloth as a highly efficient electrode for oxygen evolution reaction

Abstract

The development of highly efficient and cost-effective electrode materials for catalyzing the oxygen evolution reaction (OER) is crucial for water splitting technology. The increase in the number of active sites by tuning the morphology and structure and the enhancement of the reactivity of active sites by the incorporation of other components are the two main strategies for the enhancement of their catalytic performance. In this study, by combining these two strategies, a unique three-dimensional nanoporous Fe-Co oxyhydroxide layer coated on the carbon cloth (3D-FeCoOOH/CC) was successfully synthesized by in situ electro-oxidation methods, and directly used as a working electrode. The electrode, 3D-FeCoOOH/CC, was obtained by the Fe doping process in (NH 4 ) 2 Fe(SO 4 ) 2 , followed by continuous in situ electro-oxidization in alkaline medium of “micro go chess piece” arrays on the carbon cloth (MCPAs/CC). Micro characterizations illustrated that the go pieces of MCPAs/CC were completely converted into a thin conformal coating on the carbon cloth fibers. The electrochemical test results showed that the as-synthesized 3D-FeCoOOH/CC exhibited enhanced activity for OER with a low overpotential of 259 mV, at a current density of 10 mA cm –2 , and a small Tafel slope of 34.9 mV dec –1 , as well as superior stability in 1.0 mol L –1 KOH solution. The extensive analysis revealed that the improved electrochemical surface area, conductivity, Fe-Co bimetallic composition, and the unique 3D porous structure together contributed to the enhanced OER activity of 3D-FeCoOOH/CC. Furthermore, the synthetic strategy applied in this study could be extended to fabricate a series of Co-based electrode materials with the dopant of other transition elements. “Micro go chess piece” arrays on carbon cloth (MCPAs/CC) were transformed into a three-dimensional nanoporous iron-cobalt oxyhydroxide conformal coating on carbon cloth (3D-FeCoOOH/CC) via electrochemical oxidation. Superior OER performance was exhibited by 3D-FeCoOOH/CC, thereby outperforming IrO 2 .