Tuning Sugar Biomass Waste Conversion for the Preparation of Carbon Materials for Supercapacitors and Catalysts for Oxygen Reduction

Abstract

Agriculture is the most massive material circulation activity of humans, with significant annual volumes of production as well as substantial amounts of waste. Transforming agricultural wastes into high‐value‐added products is the key to sustainable development with efficient usage of renewable resources. The present study demonstrates the fine‐tuning of the sugar beet pulp processing to access two types of materials for cutting edge applications—supercapacitors and fuel cells. Alkaline fine‐tuning results in N,O‐doped carbon material (CM) with an advantageous combination of surface area and morphology that allows to achieve high specific capacitance (308 F g−1), and excellent stability (>10 000 charge/discharge cycles). Not limited to the CM preparation and characterization, a real device is created in the present study to demonstrate the efficient usage of the carbon electrode in the form of the assembled coin cell. Acidic fine‐tuning, in contrast, yields a methodology for P,N,O‐doped material and optimizes to form active sites with electrocatalytic activity in the oxygen reduction reaction that is used for electricity production in proton‐exchange membrane fuel cells. The developed approach demonstrates the tuning of functional properties and morphology of CMs under experimentally simple conditions using conventional reagents (KOH and H3PO4) and opens up new directions in the circular biomass usage projects.

Recent Trends in Supercapacitor Research: Sustainability in Energy and Materials

“…It should be noted that carbon materials usually contain various types of surface functional groups (SFGs), including those based on N, P, S, B, and O heteroatoms, which contribute to the pseudocapacitance resulting from surface Faraday reactions with electrolyte ions, thus affecting the increase in the overall SC capacitance. [23,29,33,[37][38][39][40][41][42][43][44][45][46][47] This field of research is booming at present (Table 1).…”

“…A unique feature of carbon materials is the possibility of obtaining them from renewable plant biomass [42,[60][61][62][63][64][65][66] and its primary processing waste, [38,44,46,47,[67][68][69] as well as agricultural wastes [39,43] (Table 1). This trend has become widespread worldwide, as can be judged by dozens of reviews published in the last few years alone (we cite only a few of them).…”

“…The high specific electrochemical performance demonstrated in this work is based on the physicochemical properties of the obtained CM. Large-tonnage waste from the processing of plant biomass generated at food industry enterprises (sugar production, [46] winemaking, [44] brewing, etc.) represents a major problem.…”

“Liquid‐To‐Solid” Conversion of Biomass Wastes Enhanced by Uniform Nitrogen Doping for the Preparation of High‐Value‐Added Carbon Materials for Energy Storage with Superior Characteristics

“…[19,20] As electrode materials in double-layer SCs, a wide range of CMs, including those obtained from plant materials, are being studied [3,4,[21][22][23][24] and solid wastes of its primary processing. [2,[25][26][27] To improve the electrochemical properties of carbon materials, doping with various heteroatoms (N, S, P, B, and F) is used, which can be incorporated into the crystal structure of graphite to form defects and various surface functional groups (SFGs), which play the role of active centers. [16,28,29] Doping with heteroatoms can significantly increase the wettability, conductivity, and stability of electrode materials and, along with the electric double layer (EDL) capacitance, provides additional pseudocapacitance due to Faraday red-ox reactions.…”