Enhanced ORR activity of S- and N-modified non-noble metal-doped carbons with bamboo-like C nanotubes grafted onto their surface

Discovering low-cost and earth-abundant electrocatalysts for oxygen reduction reaction (ORR) is essential for advanced energy conversion technologies. A large set of carbon-based ORR electrocatalysts was prepared by a two-step pyrolysis at 600 degrees C and then at 900 degrees C. Gelling sugar, guanidine acetate and cysteine were used as carbon, nitrogen and sulphur sources, respectively; iron and copper salts were utilised to produce non-noble metal-doped carbons. Silica was used as templating agent. The produced materials were thoroughly character-ized by means of BET, XPS, XRPD and micro-Raman spectroscopy to investigate their physicochemical proper-ties, and by means of RDE and RRDE methods to study their electrocatalytical properties towards ORR. They consist in sulphur-and/or nitrogen-modified carbons, some of which iron-and/or copper-doped. The massive carbonaceous structure bears bamboo-like C nanotubes onto the surface of iron-containing electrocatalysts. The best ORR electrocatalytic performance pertains to S-and N-modified carbons bearing nanotubes, which points to the occurrence of synergistic effects between heteroatoms and active sites associated to the presence of nanotubes.

Automated summary

Discovering low-cost and earth-abundant electrocatalysts for oxygen reduction reaction (ORR) is crucial for advanced energy conversion technologies. A series of carbon-based ORR electrocatalysts were prepared using a two-step pyrolysis method at 600 and 900 degrees C. Different carbon, nitrogen, and sulphur sources were utilized, along with iron and copper salts, to produce non-noble metal-doped carbons. The materials were characterized extensively, and the best ORR performance was observed in sulphur- and nitrogen-modified carbons with nanotubes, indicating the occurrence of synergistic effects between heteroatoms and nanotubes.