Activated carbon with heteroatoms from organic salt for hydrogen evolution reaction

Activated carbons (ACs) were synthesized by a simple pyrolysis of polystyrene sulfonic acid-co-maleic acid sodium salt (PSC) at 800, 850 and 900 degrees C followed by water washing. The samples were characterized by potentiometric titration, transmission electron microscopy, nitrogen adsorption isotherms, and X-ray photoelectron spectroscopy. A change in a carbonization temperature caused variations in surface areas, pore structures and sulfur/nitrogen contents. During pyrolysis some intrinsic sulfonic acid groups of PSC were decomposed as SO2, and some were embedded in the carbon matrix as thiophene sulfur and sulfones. N-2 atmosphere at high temperature with a reducing capability of the carbon surface resulted in an incorporation of nitrogen species to the carbon matrix. ACs had a hierarchical pore structure and the sample at 900 degrees C (AC-900) had a specific surface area of 960 m(2) g(-1) with V-micro/V-total at 0.4. The sample was tested for hydrogen evolution reaction (HER) in 1 M KOH, at the current density of 10 mA cm(-2). The overpotential of AC-900 was 450 mV with a Tafel slop of 163.32 mV dec(-1). The results suggested an efficient Volmer dynamics process of HER and pyridinc-N were found as contributing to the catalytic activity.