The optimal design of Co catalyst morphology on a three-dimensional carbon sponge with low cost, inducing better sodium borohydride electrooxidation activity

Abstract

A low-cost nano-flake Co@carbon sponge (Co NF@carbon sponge) electrode is prepared by a simple sponge carbonization method coupled with direct Co growth on the carbon sponge surface using pulsed electrodeposition. The catalytic activity of sodium borohydride (NaBH₄) electrooxidation in an alkaline medium are studied by cyclic voltammetry (CV) and chronoamperometry (CA). The Co NF@carbon sponge electrode reveals a unique three-dimensional (3D) nano-flake structure on the porous network skeleton with a large specific surface area and exhibits superior catalytic performance. The oxidation current density of the Co NF@carbon sponge electrode towards NaBH₄ achieves 248 mA cm⁻² in 1 mol L⁻¹ NaOH and 0.12 mol L⁻¹ NaBH₄ solution at −0.55 V (vs. Ag/AgCl) accompanied with a considerable stability, which is remarkably higher than the electrocatalytic performance of NaBH₄ oxidation obtained previously with non-noble metals as catalysts. The induced high catalytic activity greatly contributes to the excellent 3D nano-flake open structure and high electronic conductivity, which guarantees the full utilization of Co surfaces and allows the electrode to possess higher electrocatalytic performance. The novel Co NF@carbon sponge electrode is a hopeful anode with low cost and high performance for the application of fuel cells that employ NaBH₄ as the fuel.