Fabricating N, S Co‐Doped Hierarchical Macro‐Meso‐Micro Carbon Materials as pH‐Universal ORR Electrocatalysts**

Abstract

Exploring low‐cost and efficient oxygen reduction reaction (ORR) electrocatalysts is essential for clean energy conversion devices, such as fuel cells. Herein, a series of N, S co‐doped carbon‐based materials were synthesized by the one‐step pyrolysis route, using ZnCl2‐Zn(OH)2 as templates and solidago biomass as carbon and heteroatom sources. The double‐templated ZnCl2‐Zn(OH)2 system was employed to prepare the appealing carbon materials with hierarchical macro‐meso‐micro structure and high specific area. The invasive species of solidagos, as the precursors, have advantages of low cost and improved ecological diversification to some extent. The optimized catalyst (NSC‐Z2‐L) contains abundant hierarchical macro‐meso‐micro pores, high specific surface area (∼1581 m2 g−1) and N, S content (∼2.25 at.%). The special structure endows the catalyst with excellent ORR half‐wave potential (E1/2) of 0.85 V, 0.77 V and 0.76 V in the alkaline, acidic and neutral media, respectively, which are compatible with those of commercial Pt/C. The remarkable ORR performances are attributed to the hierarchically porous structure, high specific surface area and the synergistic effect of pyridinic‐N, graphitic‐N and C−S−C species. This work provides a valuable reference for achieving high‐performance ORR catalysts derived from low‐cost biomass materials.

N,S‐co‐doped FeCo Nanoparticles Supported on Porous Carbon Nanofibers as Efficient and Durable Oxygen Reduction Catalysts

“…Among these nitrogen species, pyridinic N can significantly contribute to ORR performance by weakening the O−O bond, while graphitic N enhances the conductivity of the catalyst [37] . In the same scenario, S 2p spectra also show four characteristic peaks of M−S, C−S, C=S, and S−O x at 162.09, 163.98, 165.87, and 168.41 eV [35,38] . In addition, the structural characteristic of surface oxygen atoms (O 1s) exhibits four characteristic peaks of lattice O atoms at 529.5, 531.08, 531.9, and 534.5 eV corresponding to M−O−M, C=O, C−O−C/C−OH, and O−S [39] .…”

“…[37] In the same scenario, S 2p spectra also show four characteristic peaks of MÀ S, CÀ S, C=S, and SÀ O x at 162.09, 163.98, 165.87, and 168.41 eV. [35,38] In addition, the structural characteristic of surface oxygen atoms (O 1s) exhibits four characteristic peaks of lattice O atoms at 529.5, 531.08, 531.9, and 534.5 eV corresponding to MÀ OÀ M, C=O, CÀ OÀ C/CÀ OH, and OÀ S. [39] Consequently, the results illustrate the successful preparation of N and S atoms in FeCoÀ N,S@CNFs, resulting in the introduction of N and S atoms. Their synergetic effect within the carbon materials has decreased the charge transfer resistance, enhancing their catalytic performance.…”

Advances and Perspective of Noble-Metal-Free Nitrogen-Doped Carbon for pH-Universal Oxygen Reduction Reaction Catalysts

“…Whereas dopant atoms with nearly similar electronegativity to carbon but with different atomic radii (e.g., sulfur) produce structural defects that provide extra adsorption sites for O 2 molecules . In addition, bonding between codopant atoms and a carbon matrix (e.g., F–C and S–C) can increase hydrophilicity, which enhances the transfer of reactant, adsorption of hydrated O 2 , and ORR activity, subsequently. , …”

“…76 In addition, bonding between codopant atoms and a carbon matrix (e.g., F−C and S−C) can increase hydrophilicity, which enhances the transfer of reactant, adsorption of hydrated O 2 , and ORR activity, subsequently. 151,154 Dual doping, such as codopant P atoms in Fe-N/C, was desirable to be adapted in a pH-universal application due to its ability to improve overall ORR performance. 33 The sample was derived from shrimp shells that were pyrolyzed with FeCl 3 and H 3 PO 4 at 900 °C.…”

Quantum-Chemical Modeling of the Catalytic Activity of Graphene Doped with Metal Phthalocyanines in ORR

“…At the moment, the search for non-platinum catalysts is an urgent aim, and carbon catalysts have shown the greatest promise [1][2][3][4][5]. Theoretical methods, such as quantum chemical modeling using density functional theory (DFT), are used to speed up the process of finding the optimal material [6][7][8].…”