Rational design of a bi-functional mononuclear Cobalt-dependent composite with improved catalytic activity and excellent durability for the oxygen reduction reaction

Abstract

Hydrogen peroxide is considered a mild and biocompatible oxidizer, disinfectant, and next-generation of liquid fuels. This study introduces Cobalt-rGO composite with excellent intrinsic activity for oxygen converting to hydrogen peroxide and production of electrochemical energy via a 2-electron mechanism. A good bifunctional catalyst, an economical synthesis method, high specific surface area, a meager metal value, extremely electrochemical durability, and very high selectivity at low temperature are the remarkable properties of Cobalt-rGO composite. Graphite was converted to Graphene-Oxide (GO) using a low temperature process. The oxide groups were then replaced by sulfur atoms to form a Sulfur-rGO composite. Finally, Cobalt phthalocyanine was reacted with Sulfur-rGO at 150 °C. The average pore diameter and SBET were calculated at about 27 nm and 252 m2⋅g−1, respectively. The electrochemical durability test (ΔE1/2 ≈ 0 after 10,000 cycles) and thermal gravimetric analysis were showed high stability due to the rational structure of composite. Elemental analysis has represented the Cobalt and Sulfur content about 3.66% and 3.37%, respectively. The electrons transferred number and Tafel slope were calculated about 2 and 46 mV⋅dec−1 for ORR at room temperature, respectively. The Cobalt-rGO composite is useable in fuel cells and electrochemical processes to produce hydrogen peroxide.