Deciphering Structure–Activity Relationships in Sulfur-Doped Carbon Nanomaterials through Tailored Synthesis Pathways for Efficient Electrocatalytic Oxygen Reduction

The sluggish kinetics of the oxygen reduction reaction (ORR) in zinc–air batteries (ZABs) necessitates the development of cost-effective and high-performance electrocatalysts. Herein, a delicate approach is developed to synthesize sulfur-doped carbon nanomaterials using thiophene as a single monomer through three distinct chemical reaction pathways: Scholl coupling, Knitting reaction, and conventional oxidative polymerization. By tailoring reaction pathways, we systematically regulate C–S bond content and configuration, elucidating their impact on ORR performance and establishing structure–activity relationships. The Scholl reaction-derived carbon material (SSC) achieves an optimal C–S bond content of 3.73 atom %, a high electrochemical surface area of 350 m 2 g –1, and exceptional ORR activity, with a half-wave potential of 0.83 V vs RHE and a kinetic current density of 164 mA cm –2 . SSC also exhibits superior oxygen evolution reaction (OER) performance, with a Tafel slope of 100.8 mV dec –1 and an overpotential of 440 mV at 10 mA cm –2 . Flexible ZABs based on SSC cathodes deliver a stable 1.2 V output over 120 min and power wearable electronics, demonstrating practical applicability. This work offers a versatile approach for designing high-performance sulfur-doped carbon-based electrocatalysts, advancing sustainable energy storage technologies.