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

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. [ABSTRACT FROM AUTHOR]