Molten state synthesis of promising carbon sulfur electrocatalyst for oxygen evolution reaction in acidic media

In recent years, carbon materials have emerged as promising materials for wide range of energy related applications such as photo and electrocatalytic water splitting, super capacitators, batteries and water cleaning, due to their superb conductivity, strong mechanical strength, and thermal conductivity. Introduction of heteroatoms such as sulfur into the carbon network, enables the tuning of various properties (conductivity, oxidation stability, and catalytic activity) only by changing the sulfur amount inside the carbon matrix. Sulfur has a lower electronegativity than carbon which induces an electron rich carbon. In addition, sulfur’s covalent radius is larger than carbon which causes deformation in the carbon network and enables more catalytically reactive sites. These properties enable the utilization of CS composite materials in various electrochemical applications.

Usually the synthesis of these materials is carried out in gaseous or solid state reactions. Although a wide range of materials were synthesized by these reactions there are several drawbacks. Gaseous methods are expensive (due to the use of metallic catalysts) and exhibit very low scalability, while in the solid state reaction it`s very hard to control the elemental composition of the final materials and the use of hard/soft templating is usually needed. Herein we show a new, scalable and easy way to synthesize carbon sulfur (CS) materials by means of molten state intermediate. The CS materials exhibit excellent thermal and chemical stability, electric conductivity, and large surface area which are easily tuned by controlling the sulfur amount in the material using this simple method (up to 20% S). Moreover, the materials show promising activity in acidic electrochemical oxygen evolution reaction (OER) as they are stable after excessive cycling.