RNA as a Precursor to N‑Doped Activated Carbon

Activated carbons (ACs) have applications in gas separation and power storage, and N-doped ACs in particular can be promising supercapacitors. In this context, we studied ACs produced from yeast-derived ribonucleic acid (RNA), which contains aza-aromatic bases and phosphate-linked ribose units, and is surprisingly inexpensive. The RNA was hydrothermally carbonized to produce hydrochars that were subsequently activated with CO₂, KOH, or KHCO₃ to give ACs. The ACs adsorbed up to ∼7 mmol/g at 0 °C and 1 bar and had capacitances as high as ∼300 F/g in a three-electrode cell and a 6 M KOH­(aq) electrolyte. The material that displayed the best capacitance was tested in a two-electrode cell, which displayed a specific capacitance of 181 F/g even at a current density of 10 A/g. The ACs with the highest uptake of CO₂ and the highest capacitance were those activated with KOH and KHCO₃; however, CO₂ activation is arguably less expensive and more suitable for industrialization.