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Fe single‐atom catalysts (SACs) are a promising catalyst for oxygen reduction reaction (ORR) in both Zn–air batteries (ZABs) but have a certain distance to compete with Pt‐based catalysts. Rational modulation of the coordination environment in the second coordination shell of SACs offers an opportunity to improve the intrinsic ORR activity, yet a challenge. Here, a novel strategy is reported to construct a dual‐metal catalyst by introducing a single Co atom in the second coordination shell of the Fe center. The dual‐metal N3─Fe─N─Co site with a certain Fe─Co distance of 0.312 nm is constructed. It allows for manipulation of the positive shift of the Fe center charge state, driving the d‐band center up‐shift by 0.63 eV, thereby offering the optimal adsorption of intermediates. Benefiting from this structure, the as‐prepared Fe(Co2nd)‐NC enables an excellent ORR activity with a half‐wave potential of 0.948 V in 0.1 M KOH. As a cathode in ZABs, it delivered an outstanding peak power density of 218 mW cm−2 and a specific capacity of 915 mAh gZn−1 at 5 mA cm−2, respectively, with superior long‐term durability over 680 h. The second shell layer alignment regulation strategy shows great potential for energy storage applications. [ABSTRACT FROM AUTHOR]

The two‐electron pathway to form hydrogen peroxide (H2O2) is undesirable for the oxygen reduction reaction (ORR) in iron and nitrogen doped carbon (Fe–N–C) material as it not only lowers the catalytic efficiency but also impairs the catalyst durability. In this study, a relay catalysis pathway is designed to minimize the two‐electron selectivity of Fe–N–C catalyst. Such a design is achieved by introducing two other sites, that is, MnN4 site and α‐Fe(110) face. A combination of transmission electron microscopy image and X‐ray absorption spectra verify the three site formation. Electrochemical test coupled with post‐treatment confirm the improvement of MnN4 site and α‐Fe(110) face on catalyst performance. Theoretical calculation proposes a relay catalysis pathway of three sites, that is, H2O2 released from the FeN4 site migrates to the MnN4 site or α‐Fe(110) face, on which the captive H2O2 is further reduced to H2O. The relay catalysis pathway positioned the as‐prepared catalyst among the best ORR catalysts in both aqueous electrode and alkaline direct methanol fuel cell test. This study examples an interesting relay catalysis pathway of multi‐sites for the ORR, which offers insights into the design of efficient electrocatalysts for fuel cells or beyond. [ABSTRACT FROM AUTHOR]

The preparation of metal electrocatalysts with excellent comprehensive properties for application in alcohol fuel cells is an urgent issue. This study reports a novel 3D Au‐doped PtBi intermetallic phase woven by sub‐7 nm building blocks. The high‐efficiency "active auxiliary" Au advances the activity and in situ anti‐CO poisoning upon ethylene glycol electrooxidation on 3D PtBiAu, along with high CC bond cleavage and attainment of a ten‐electron complete electrooxidation via a CO‐free pathway. The interface‐rich 3D structure with "nanocontainer" function, electronic effect, and dual functional sites of "Pt–Au" or "Pt–Bi" enable the 3D PtBiAu to outperform industrial Pt black and 3D PtBi intermetallics significantly. The mass activity on the 3D Pt53.1Bi43.4Au3.5 intermetallics boosts to 28.72 A mgPt−1, higher than that reported in a previous study. The 3D Pt53.1Bi43.4Au3.5 exhibits superior performance to industrial Pt/C in direct ethylene glycol fuel cells (DEGFCs). The peak power density of 3D Pt53.1Bi43.4Au3.5 is 145/92 mW cm−2 in O2/air (80 °C). Importantly, the cell voltage shows a negligible decay in both O2 and air during the 20 h durability testing. This study results in the development of novel 3D PtBiAu intermetallics as high‐performance anode electrocatalysts for application in DEGFCs. [ABSTRACT FROM AUTHOR]

Metal and nitrogen-doped carbon (M-N-C) materials have been considered as the most promising non-precious metal oxygen reduction (ORR) catalysts to replace expensive Pt catalysts. Due to high Fenton catalytic activity of Fe element and the resulting instability, Co-based N–C (Co–N–C) catalysts without Fenton catalytic activity should be a worthier ORR catalyst being explored. Although the high ORR activity of Co–N–C catalyst has been demonstrated in aqueous half-cell tests, their performance under PEMFC working condition is still far away from that of state-of-the-art Fe–N–C catalysts. In this study, a high-performance Co–N–C catalyst was synthesized by one-step pyrolyzing Co-doped ZIF-8 (zeolitic imidazolate framework-8) particles in-situ grown on the high-surface-area KJ600 carbon black with high electronic conductivity. The resulting Co–N–C catalyst exhibited high intrinsic ORR activity, fast mass transfer rate and high electronic conductivity, and thus yielded a remarkable peak power density of 0.92 W cm-2 in H 2 –O 2 PEMFC, which is comparable to state-of-the-art Fe–N–C catalyst. This strategy is helpful to synthesize highly active M-N-C ORR catalysts with improved mass transfer and electric conductivity. Image 1 • Porous carbon supporting to prevent the aggregation of ZIF8 particles. • A high-performance ZIF-based Co–N–C catalyst is fabricated. • A remarkable peak power density of 0.92 W cm-2 in H 2 –O 2 PEMFC. [ABSTRACT FROM AUTHOR]

PtCu hollow octahedral nanoparticles with wall thickness of ~2.1 nm have been successfully achieved to be as efficient bifunctional electrocatalysts toward oxygen reduction reaction and methanol oxidation reaction. • PtCu hollow octahedrons (HOs) with wall thickness of ~2.1 nm have been achieved. • The MA of PtCu/C HOs toward ORR boosts to 2.60 A mg Pt -1. • After 10,000 voltage cycles, the MA of Pt 44.1 Cu 55.9 /C HONs remains 1.63 A mg Pt -1. • The optimum MA of methanol electrooxidation on PtCu/C HONs is 1.94 A mg Pt -1. In response to the scarcity of precious metals, the development of precious-metal-saving electrocatalysts exhibiting high mass activity (MA) and durability towards oxygen reduction reaction (ORR) and methanol oxidation reaction (MOR) for both proton-exchange membrane fuel cells (PEMFCs) and direct methanol fuel cells (DMFCs) has aroused increasing attention. In this study, octahedral Cu-rich PtCu alloy is seeded to fabricate near-surface composition-tunable PtCu hollow octahedral nanoparticles (HONs) with the wall thickness of ~2.1 nm. Due to both the alloying effects of near surface and the special hollow octahedral structure, the PtCu/C HONs exhibit significantly higher MA and durability than commercial Pt/C towards both ORR in alkaline medium and MOR in sulfuric acid electrolyte. The ORR MA of Pt 44.1 Cu 55.9 /C HONs are up to 2.60 A mg Pt −1 that is 18.5-fold enhancement compared with that of Pt/C. Besides, after 10,000 voltage cycles, the MA of Pt 44.1 Cu 55.9 /C HONs remains to be 1.61 A mg Pt −1, a datum 53.7 times that of Pt/C. The in situ CO polarization curves exhibit that the Pt 44.1 Cu 55.9 HONs/C own high resistance to CO poisoning. For MOR in sulfuric acid electrolyte, the optimum SA/MA of PtCu/C HONs is 5.33 mA cm−2/1.94 A mg Pt −1, which is 10.25/5.87 times higher than that of Pt/C. This study provides effective bifunctional cathode and anode electrocatalysts for both PEMFCs and DMFCs. [ABSTRACT FROM AUTHOR]