Synthesis of N-doped carbon based on the waste of Brosimum alicastrum from a pilot plant and evaluation of its electrocatalytic activity for the oxygen reduction reaction

This work reports the synthesis and characterization of metal-free electrocatalysts made from Brosimum alicastrum waste as the carbon source. The residues were washed and grounded to a fine powder. The thermogravimetric analysis carried out on the raw sample showed that the optimal synthesis temperature is 700 °C. Thus, the raw sample was pyrolyzed at 700 °C and activated with potassium hydroxide (KOH) in a 2:1 ratio (KOH/fine power) to improve its properties. Afterwards, hydrazine was used as the nitrogen source for doping. The physicochemical characteristics of pyrolyzed, activated, and doped carbons were studied and their electrochemical properties were determined using cyclic and linear voltammetry techniques. The electrochemical measurements indicate that the sample doped at 140 °C has an acceptable onset potential (0.854 V vs. RHE), while the one doped at 160 °C shows the highest current density among the synthesized electrocatalysts (2.61 mA cm-2). Although the catalyst performance is lower compared to commercial 20% Pt/C, this biomass precursor favors the oxygen reduction reaction in alkaline media.