N-, F-, and Fe-Doped Mesoporous Carbon Derived from Corncob Waste and Creating Oxygen Reduction Reaction Active Centers with a Maximum Charge Density of ≥0.25 for a Polymer Electrolyte Fuel Cell Catalyst

Abstract

Defect chemistry, increasing charge, and spin density in the carbon lattice are keys to the advancement of any alternative non-precious cathodic oxygen reduction electrocatalyst for broad dissemination of polymer electrolyte fuel cells (PEFCs). In view of this prospective, we developed porous carbon from a biomass-derived source, such as corncob (CC) waste, and heteroatom N and F doping on it to increase functionalities and defects. Fe was further incorporated in N–F/CC-C to enhance the oxygen reduction reaction (ORR) activity and power density in PEFCs. Finely mesoporous carbon derived from CC undergoes structural transformation, having numerous open edge active sites after N–F co-doping, and alters the textural characteristics favorable for ORR. The Fe/N–F/CC-C catalyst shows outstanding ORR activity, insensitivity toward CH3OH in alkaline conditions, and insignificant deprivation in ORR activity after a recurrent 10 000 potential cycles that prevails a highly enticing ORR electrocatalyst for PEFCs. The presence of active pyridinic, pyrrolic, and graphitic kinds of nitrogen along with ionic and semi-ionic active bonds between C and F in graphitic arrangement of the Fe/N–F/CC-C catalyst cumulatively ameliorates the catalytic activity. Furthermore, generation of maximal C–C bond polarization, redistribution in charge density, and high spin densities in the carbon lattice of the catalysts were theoretically investigated, which cumulatively boost the ORR activity.

Co-, Ni-Catalyzed Borylation of Carbon Nanofibers for Oxygen Reduction Reaction in an Anion Exchange Membrane Fuel Cell

“…Figure elucidates the positive–negative charge distribution of B heteroatoms and metal doped on the carbon matrix along with a distinct approach toward the reactivity of the complexes. In order to comprehend the reactivity or steadiness of the geometrical structure, all geometries are optimized using UB3LYP function, 6-31G­(d,p) basis set, and spin unrestricted setting level with Gaussian 16 program suite . Anecdotal information reveals that insertion of B atom in the carbon matrix replaces the carbon atom and forms C–B bond in the matrix that creates charge, with spin density variation adjacent to it .…”

“…In order to comprehend the reactivity or steadiness of the geometrical structure, all geometries are optimized using UB3LYP function, 6-31G(d,p) basis set, and spin unrestricted setting level with Gaussian 16 program suite. 64 Anecdotal information reveals that insertion of B atom in the carbon matrix replaces the carbon atom and forms C−B bond in the matrix that creates charge, with spin density variation adjacent to it. 77 Further, metal atom, after doping sits in the carbon position without having any proof of interaction with heteroatom in the graphene matrix.…”

“…Carbon materials, namely carbon nanotubes (CNT), carbon nanofibers (CNF), graphene, and graphitic carbon nanofiber (GNF) are extensively explored as potential support material owing to their structural benefits, high graphitic nature, and adequate surface area with high mechanical properties. − Among GNFs bearing adequate porous fibrous structures, filamentary micropatterned frameworks, exposed inclines, carrier mobility, and arrangement of graphene platelets to the base-axis tends to create an extremely active ORR catalytic site and thus they are considered as an excellent support material when designing any cathode catalyst. − Recently, S. Akula et al reported on GNFs and heteroatom engineering and described several types of GNFs with crystallographic alignment and morphology, viz., linear platelet, antler, cylindrical, and herringbone types, which starts a new era in developing potential corrosion resistant support material. − The two-dimensional (2D) fish skeleton herringbone type structure of GNF (GNF-H) facilitates a way out for the detailed study owing to its greater electrochemical behavior as compared to other structural orientations. , Furthermore, introduction of hetero elements (such as N, B, S, P, F, etc.) on graphitic surface reports higher spin density and charge density as it brings on numerous defects and electronic charge distribution in the particle, further enhancing its catalytic activity. − Moreover, boron doping takes much attention on account of its smaller atomic size and closed electronegativity with carbon and thus lowers energy barrier between them. − Many researchers’ showed an interest in doping of boron on graphitic nanostructures and investigating it both experimentally and theoretically. DFT calculations observed during various literature study clarify how boron can effectively replace the carbon atom in the graphene latticework owing to the lower energy barrier between them.…”

High Performing Chemically Ordered Pt2CoNi/Ti@C as an Efficient and Stable Cathode Catalyst for Oxygen Reduction

“…The PEMFCs performance evaluation for both Pt/C 20% and Pt 2 CoNi/Ti@C catalysts were measured at 45 and 70 °C. The cell temperature was measured at the Al end plate wherein heating and sensing provision are made . The experiments were repeated several cycles to equilibrate and get reproduced data.…”

“…The cell temperature was measured at the Al end plate wherein heating and sensing provision are made. 42 The experiments were repeated several cycles to equilibrate and get reproduced data. The polarization data were collected point by point, and 1 min was provided for the system to reach a steady state.…”