Fe-N-C materials with atomically dispersed Fe–N₄ sites could tolerate the poisoning of phosphate, and is regarded as the most promising alternative to costly Pt-based catalysts for the oxygen reduction in high temperature polymer electrolyte membrane fuel cells (HT-PEMFCs). However, they still face the critical issue of insufficient activity in phosphoric acid. Herein, we demonstrate a P-doping strategy to increase the activity of Fe-N-C catalyst via a feasible one-pot method. X-ray absorption spectroscopy and electron microscopy with atomic resolution indicated that the P atom is bonded with the N in Fe–N₄ site through C atoms. The as prepared Fe-NCP catalyst shows a half-wave potential of 0.75 V (vs. reversible hydrogen electrode (RHE), 0.1 M H₃PO₄), which is 60 and 40 mV higher than that of Fe-NC and commercial Pt/C catalysts, respectively. More importantly, the Fe-NCP catalyst could deliver a peak power density of 357 mW·cm⁻² in a high temperature fuel cell (160 °C), exceeding the non-noble-metal catalysts ever reported. The enhancement of activity is attributed to the increasing charge density and poisoning tolerance of Fe–N₄ caused by neighboring P. This work not only promotes the practical application of Fe-N-C materials in HT-PEMFCs, but also provides a feasible P-doping method for regulating the structure of single atom site.

Rechargeable aqueous zinc ion batteries (AZIBs) based on manganese dioxide (MnO₂) have received much attention for large-scale energy storage applications, however, their energy density is mainly limited by the one-electron reaction of Mn⁴⁺/Mn³⁺ redox. Herein, Mo doped δ-MnO₂ (Mo-MnO₂) is prepared and used as a high-performance cathode for AZIBs, which delivers an ultrahigh specific capacity of 652 mAh·g⁻¹ at 0.2 A·g⁻¹ based on the two-step two-electron redox reaction of Mn⁴⁺ $\rightleftharpoons$ Mn³⁺ $\rightleftharpoons$ Mn²⁺. Ex-situ structural analysis and density functional theory calculation reveal that the Mo⁵⁺ dopant plays an important role in enhancing the electronic conductivity of Mo-MnO₂ and promoting Jahn–Teller distortion of octahedral [MnO₆] in ZnMn₂O₄, which facilitates the second step redox reaction of Mn³⁺/Mn²⁺. This work provides a novel cathode materials design with multi-electron redox chemistry to achieve high energy density in AZIBs.

Oxygen reduction efficiency holds the key for renewable energy technologies including fuel cells and metal-air batteries, which involves coupling diffusion-reaction-conduction processes at the interface of catalyst/electrolyte, and thus rational electrode design facilitating mass transportation stands as a key issue for fast oxygen reduction reaction (ORR). Herein, we report a Janus electrode with asymmetric wettability prepared by partly modifying aerophobic nitrogen doped carbon nanotube arrays with polytetrafluoroethylene (PTFE) as a high performance catalytic electrode for ORR. The Janus electrode with opposite wettability on adjacent sides maintains stable gas reservoir in the aerophilic side while shortening O₂ pathway to catalysts in the aerophobic side, resulting in superior ORR performance (22.5 mA/cm² @ 0.5 V) than merely aerophilic or aerophilic electrodes. The Janus electrode endows catalytic performance even comparable to commercial Pt/C in the alkaline electrolyte, exploiting a previously unrecognized opportunity that guides electrode design for the gas-consumption electrocatalysis.