Single Fe Atom on Hierarchically Porous S, N‐Codoped Nanocarbon Derived from Porphyra Enable Boosted Oxygen Catalysis for Rechargeable Zn‐Air Batteries

<jats:title>Abstract</jats:title><jats:p>Iron–nitrogen–carbon materials (Fe–N–C) are known for their excellent oxygen reduction reaction (ORR) performance. Unfortunately, they generally show a laggard oxygen evolution reaction (OER) activity, which results in a lethargic charging performance in rechargeable Zn–air batteries. Here porous S‐doped Fe–N–C nanosheets are innovatively synthesized utilizing a scalable FeCl<jats:sub>3</jats:sub>‐encapsulated‐porphyra precursor pyrolysis strategy. The obtained electrocatalyst exhibits ultrahigh ORR activity (<jats:italic>E</jats:italic><jats:sub>1/2</jats:sub> = 0.84 V vs reversible hydrogen electrode) and impressive OER performance (<jats:italic>E<jats:sub>j</jats:sub> </jats:italic><jats:sub>= 10</jats:sub> = 1.64 V). The potential gap (Δ<jats:italic>E</jats:italic> = <jats:italic>E<jats:sub>j</jats:sub> </jats:italic><jats:sub>= 10</jats:sub> − <jats:italic>E</jats:italic><jats:sub>1/2</jats:sub>) is 0.80 V, outperforming that of most highly active bifunctional electrocatalysts reported to date. Furthermore, the key role of S involved in the atomically dispersed Fe–N<jats:italic>x</jats:italic> species on the enhanced ORR and OER activities is expounded for the first time by ultrasound‐assisted extraction of the exclusive S source (taurine) from porphyra. Moreover, the assembled rechargeable Zn–air battery comprising this bifunctional electrocatalyst exhibits higher power density (225.1 mW cm<jats:sup>−2</jats:sup>) and lower charging–discharging overpotential (1.00 V, 100 mA cm<jats:sup>−2</jats:sup> compared to Pt/C + RuO<jats:sub>2</jats:sub> catalyst). The design strategy can expand the utilization of earth‐abundant biomaterial‐derived catalysts, and the mechanism investigations of S doping on the structure–activity relationship can inspire the progress of other functional electrocatalysts.</jats:p>