Waste‐Derived Biocarbons as Nonnoble Metal Catalysts and Supports for Nanocatalysts for Fuel Cells Reactions in Alkaline Media

Abstract

Encouraging results have been obtained from the characterization and testing of biocarbons derived from widely available waste biomass, foreseeing their use in anion exchange membrane fuel cells (AEMFC). Pyrolysis is the most common route to synthetize biocarbons from biomass, but hydro‐ and solvothermal treatments have gained attention because of the possibility of developing hierarchically ordered structures. In most cases, biocarbons from biomass are self‐doped with heteroatoms, although the relative concentration of those species can be increased by doping during the thermal treatment of the biomass. Moreover, their surface chemistry can be modified to create functional groups that act as centers for the adsorption of molecules and the anchorage of nanoparticles. The most common application of the structurally disorder and amorphous biocarbons is as self‐standing metal‐free electrocatalysts for the oxygen reduction reaction (ORR). To a lesser extent, biocarbons have been investigated as supports of noble metal and nonnoble metal nanoparticles. In the first case, the application has been mostly as anodes for the oxidation of organic molecules, since Pt and Pd are highly active for such reactions. In the second, the impregnation of biocarbons mainly with Co and Fe nanoparticles has promoted a high catalytic activity for the ORR. Being produced from cheap biomass resources, the technological challenge of biocarbons is to achieve the high electrocatalytic performance required to contend with, and eventually replace, the benchmark Pt/C (as electrocatalysts) and Vulcan XC‐72 (as support).

Fe-N-C Self-Doped Sewage Sludge-Derived Biocarbon With Catalytic Activity For The Oxygen Reduction Reaction

“…Biomass-derived biocarbons are one of the most promising alternatives to replace PMG electrocatalysts and to accomplish high-performances and stability toward the ORR in alkaline media (5). The catalytic activity is promoted by nitrogen species such as pyridinic-N and quaternary-N, or some other heteroatom incorporated into the carbon lattice (ex.…”