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Highly active Pt‐based intermetallic nanoparticles (i‐NPs) loaded on stable supports have garnered considerable interest as promising oxygen reduction reaction (ORR) catalysts for proton‐exchange‐membrane fuel cells (PEMFCs). Herein, thermostable tellurium (Te) is vapor‐deposited onto commercial conductive carbon to anchor high‐temperature‐synthesized Pt3Co i‐NPs. Advanced characterization and density functional theory (DFT) calculations demonstrate that the binding energy of Pt 4f and Co 2p shift positively by 0.12 and 0.95 eV after the introduction of Te in carbon support, promoting the formation of Pt─Te bonds, which enhances the metal–support interactions (MSIs) in Pt3Co/Te‐C (with a more negative binding energy of −10.28 eV). The average size of well‐dispersed Pt3Co i‐NPs (≈3.9 nm) on Te─C is considerably smaller than that of Pt3Co i‐NPs (≈9.1 nm) on commercial carbon. The specific activity of Pt3Co/Te‐C decreases by only 1.5% after 100,000 ultra‐long voltage‐accelerated cycles, while the morphology remains almost unchanged. The membrane electrode assembly using Pt3Co/Te‐C as a cathode demonstrates impressive activity (power density of 2.32 W cm−2@4 A cm−2 and mass activity of 0.50 A mgPt−1@0.9 V) and robust durability (mass activity@0.9 V loss of 26% after 30,000 cycles with intact L12 ordered structure) in H2–O2 operation, significantly exceeding the DOE 2025 requirements. [ABSTRACT FROM AUTHOR]

Atomically distributed transition metal coordinated with nitrogen is considered as a class of promising oxygen reduction reaction (ORR) catalyst. However, the challenge of ineffective distribution of Fe‐Nx active sites have been long existing, leading to low active site density and unstable performance, which needs be overcome for next generation ORR electrocatalysts. Herein, yttrium (Y) is introduced into atomically dispersed iron (Fe) nitrogen co‐doped carbon materials to integrate nanoparticles, nanoclusters, and atomic sites, which endow the Fe‐N4‐Y2O3 and Fe4N0.94‐Y2O3 (FeY‐NC) with outstanding ORR activity. The FeY‐NC achieves half‐wave potential of 0.926 and 0.809 V in alkaline and acidic condition, respectively. The kinetics current density at 0.9 V in alkaline condition is 31.2 mA cm−2, which is 7.8 times of Fe‐NC and 32.4 times of Pt/C. This outstanding activity of FeY‐NC is enabled by the generated atomic FeN4 and Fe4N nanoparticles dual active‐sites, and further the synergistic effect between the Fe‐Nx/Fe4N0.94 with Y2O3 nanoclusters are loaded on nitrogen‐doped carbon (NC) network. The superior performance of FeY‐NC is demonstrated in a primary Zinc‐air battery, deliver a peak power density of 233 mW cm−2. [ABSTRACT FROM AUTHOR]

The energy crisis and environmental issues are becoming more severe due to the long-term consumption of fossil fuels. Therefore, novel energy-conversion devices with high energy density and environmental friendliness are expected to provide reliable alternatives to traditional fossil-based energy systems. However, because of the inevitable use of costly precious metals as the electrode catalysts for such devices, their popularization is seriously hindered. Transition metal nitrides (TMNs) exhibit similar surface and adsorption properties to noble metals because the atomic distance between metal atoms increases and the d-band center of metal atoms downshifts after nitrogen atoms enter the metal lattice. TMNs have become one of the best electrode materials to replace noble metal-based electrocatalysts in next-generation energy-storage and energy-conversion devices. In this review, the recent developments in the electrocatalytic application of TMNs are covered. First, we discuss the structure and activity origin of TMNs and introduce the common synthesis methods for the preparation of TMNs. Subsequently, we illustrate the applications of mono-metallic TMNs and multi-metallic TMNs in oxygen-reduction reaction, oxygen-evolution reaction, and bifunctional oxygen reduction and evolution reactions. Finally, we summarize the challenges of TMNs encountered at the present stage, and expect their future development. [ABSTRACT FROM AUTHOR]

Summary: Exploring progressed activity and stability, electrocatalyst toward oxygen reduction reaction (ORR) and oxygen evolution reaction (OER), has been the most considerable factor in extensive commercialization of metal‐air batteries and fuel cells. Herein, Co/N co‐doped 3D hierarchical porous bifunctional oxygen electrocatalyst was synthesized using F127 as soft template and PMMA nanosphere as hard template to build hierarchically ordered macro/mesoporous porous nanostructure. The as‐obtained macro/mesoporous Co‐N‐doped carbon endowing its 3D ordered hierarchical porosity and satisfactory surface area, leading to superior performance for ORR, OER, and rechargeable Zn‐air battery. For ORR, the catalyst showed superior ORR activity with an attractive half‐wave potential of 0.85 V (vs RHE), remarkable methanol tolerance, and robust long‐term stability under alkaline electrolyte. For OER, the as‐synthetized electrocatalyst exhibited low overpotential of 1.67 V (vs RHE) under the current density of 10 mA/cm2. Moreover, the Zn‐air battery assembled from the hierarchical porous catalyst displayed a high peak power density of 146 mW/cm2. [ABSTRACT FROM AUTHOR]

Developing high efficiency and durability catalysts for the electrocatalytic oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) is fundamental to achieve the large‐scale commercial application of fuel cells and metal‐air batteries. Herein, a series of Co−N doped bi‐functional hierarchical porous electrocatalysts were synthesized using polyvinyl pyrrolidone (PVP) as soft template to assist the Zn/Co bimetal Zeolitic Imidazolate Framework (BMZIF) to form micro‐/mesoporous carbon nanospheres via a convenient one‐step solution synthesis method, followed by pyrolysis to form carbon nanospheres catalysts. The as‐prepared Co/N co‐doped carbon exhibits outstanding performances in the ORR and OER due to the formed hierarchical pores architecture and the high surface area. The catalyst displays superior ORR performance with a high half‐wave potential of 0.89 V, and a remarkable long‐term stability in 0.1 M KOH. In addition, the electrocatalyst elicits a low voltage of 1.72 V under the current density of 10 mA cm−2. Moreover, the zinc‐air battery fabricated with P‐CNCo‐3 delivers a power density of 175.1 mW cm−2, a high specific capacity of 791 mAh g−1 and an energy density of 976 Wh kg−1 at 20 mA cm−2. [ABSTRACT FROM AUTHOR]

A novel method for the preparation of iron‐ and nitrogen‐codoped carbon nanotubes (Fe‐N‐CNTs) is proposed, based on the catalytic pyrolysis of waste plastics. First, carbon nanotubes are produced from pyrolysis of plastic waste over Fe‐Al2O3; then, Fe‐CNTs and melamine are heated together in an inert atmosphere. Different co‐pyrolysis temperatures are tested to optimize the electrocatalyst production. A high doping temperature improves the degree of graphite formation and promotes the conversion of nitrogen into a more stable form. Compared with commercial Pt/C, the electrocatalyst obtained from pyrolysis at 850 °C shows remarkable properties, with an onset potential of 0.943 V versus RHE and a half‐wave potential of 0.811 V versus RHE, and even better stability and anti‐poisoning properties. In addition, zinc–air battery tests are performed, and the optimized catalyst exhibits a high maximum power density. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Oxygen reduction reaction catalysts based on bimetallic-organic framework. • Building hierarchical pore structures using soft templates combined with Zn evaporation. • The optimal catalyst exhibits ORR performance comparable to Pt/C in acidic medium. • Efficient and low-cost cathode catalyst for polymer electrolyte fuel cells. Abstract The development of highly active and cost-efficient electrocatalysts toward oxygen reduction reaction (ORR) is essential for widespread application of polymer electrolyte fuel cell (PEFC). In the present work, hierarchically structured porous Co-Zn-N-C electrocatalyst is prepared by using soft templated bimetallic-organic framework precursors. The as-synthesized hierarchically porous catalyst presents outstanding ORR onset-potential (0.88 V vs. RHE), half-wave potential (0.78 V vs. RHE), and diffusion limiting current density (5.73 mA cm−2), that is similar to that at commercial Pt/C catalyst in acidic electrolyte. It is found that the hierarchical porous architecture is important for its excellent catalytic activity and further testifies that the hierarchically porous electrocatalyst also exhibits superior single PEFC performance with a power density of 412 mV cm−2. The present work provides not only a facile and low cost strategy toward the preparation of hierarchically porous materials, but also inspires an approach for enhancing the ORR electrocatalytic activity of MOF-derived materials. [ABSTRACT FROM AUTHOR]

Non-precious materials have been considered as promising bifunctional catalysts towards oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). In the present work, a three dimensional (3D) Co-N co-doped hollow carbon sphere (HCS) electrocatalyst is synthesized at room temperature by the aid of a facile preparation method. The as obtained Co-N co-doped catalyst exhibits excellent catalytic activity towards both ORR and OER due to its high surface area and to 3D hollow architecture. For the ORR, the catalyst shows more positive onset-potential (of ∼0.962 V vs. RHE) and larger diffusion limiting current density (5.55 mA cm −2 ) compared with benchmark Pt/C catalyst in alkaline medium. Moreover, the as synthesized catalyst exhibits low potential (1.720 V vs. RHE) at the current density of 10 mA cm −2 and small Tafel slope (81 mV dec −1 ) for OER. In addition, the catalyst exhibits remarkable methanol tolerance and good long-term stability under working conditions. This strategy provides a facile and effective method for the preparation of non-noble metal catalysts with 3D hollow structure for energy conversion and storage applications. [ABSTRACT FROM AUTHOR]

The oxygen reduction reaction (ORR) is crucial to the development of fuel cell and metal-air battery. Metals with atomic-level dispersion has been considered as the effective nano-technologies to promote the activity and stability of catalysts for ORR. Herein, we designed Fe/N-doped porous carbon (Fe-NPC) as efficient ORR catalysts in both alkaline and acid electrolyte through a simplified one-pot method. The Fe species were atomically dispersed in the synthesized materials by FeN 4 C 10 moieties and exhibited excellent electrocatalytic performance. Experimental and theoretical results showed that Fe–N 4 sites existed in Fe-NPC endowed it with high intrinsic catalytic activity for ORR. When utilized as air electrode catalyst in Zn-air battery, Fe-NPC material achieved a maximum power density (126.0 mW cm−2) and could operate steadily for over 11 h. This work presents a simplified strategy in the design and synthesis of sing-atom catalysts electrocatalysts with high activity and stability, paving the way for the mass production and mechanistic studies of catalysts in reality. • Single iron atoms dispersed electrocatalyst has been designed. • The FeN 4 C 10 moieties have been identified to be the catalytic sites. • The Zn-air battery performance of the catalyst has been measured. [ABSTRACT FROM AUTHOR]