In this study, we have evaluated the effect of potassium hydroxide (KOH) on the energy storage performance of metal-free carbon-based materials prepared from molasses. Molasses are a renewable-resource biomass and economical by-product of sugar refinement, used here as a carbon precursor. Two co-doped carbon materials using molasses were synthesized via a time and cost-efficient microwave carbonization process, with ammonium polyphosphate as a phosphorus and nitrogen doping agent. The phosphorus and nitrogen co-doped carbon (PNDC) samples were prepared in the presence and absence of a chemical activating agent (KOH), to study the role of chemical activation on PNDCs. Physical characterizations were performed to gain insight into the composition, pore size and topographical data of each material. Electrochemical characterization via cyclic voltammetry in 1 M sulfuric acid (H2SO4) as well as in 6 M KOH as electrolytes, revealed high current density and specific capacitance for the chemically activated material (PNDC2) compared to one without chemical activation (PNDC1). The capacitance value of 244 F/g in KOH electrolyte was obtained with PNDC2. It is concluded that addition of KOH prior to carbonization increases the surface functionality, which significantly enhances the electrochemical properties of the PNDC material such as current density, stability, and specific capacitance.

Fuel cells are a promising alternative to non-renewable energy production industries such as petroleum and natural gas. The cathodic oxygen reduction reaction (ORR), which makes fuel cell technology possible, is sluggish under normal conditions. Thus, catalysts must be used to allow fuel cells to operate efficiently. Traditionally, platinum (Pt) catalysts are often utilized as they exhibit a highly efficient ORR with low overpotential values. However, Pt is an expensive and precious metal, posing economic problems for commercialization. Herein, advances in carbon-based catalysts are reviewed for their application in ORRs due to their abundance and low-cost syntheses. Various synthetic methods from different renewable sources are presented, and their catalytic properties are compared. Likewise, the effects of heteroatom and non-precious metal doping, surface area, and porosity on their performance are investigated. Carbon-based support materials are discussed in relation to their physical properties and the subsequent effect on Pt ORR performance. Lastly, advances in fuel cell electrolytes for various fuel cell types are presented. This review aims to provide valuable insight into current challenges in fuel cell performance and how they can be overcome using carbon-based materials and next generation electrolytes.

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Renewable resources and their byproducts are becoming of growing interest for alternative energy. Here, we have demonstrated the use of Arkansas’ most important crop, soy, as a carbon precursor for the synthesis of carbonized activated materials for supercapacitor applications. Different soy products (soymeal, defatted soymeal, soy flour and soy protein isolate) were converted into carbonized carbon and co-doped with phosphorus and nitrogen simultaneously, using a facile and time-effective microwave synthesis method. Ammonium polyphosphate was used as a doping agent which also absorbs microwave radiation. The surface morphology of the resulting carbonized materials was characterized in detail using scanning electron microscopy. X-ray photoelectron spectroscopy was also performed, which revealed the presence of a heteroelemental composition, along with different functional groups at the surface of the carbonized materials. Raman spectroscopy results depicted the presence of both a graphitic and defect carbon peak, with defect ratios of over one. The electrochemical performance of the materials was recorded using cyclic voltammetry in various electrolytes including acids, bases and salts. Among all the other materials, soymeal exhibited the highest specific capacitance value of 127 F/g in acidic electrolytes. These economic materials can be further tuned by changing the doping elements and their mole ratios to attain exceptional surface characteristics with improved specific capacitance values, in order to boost the economy of Arkansas, USA.