The development of high-efficiency and durable bifunctional electrocatalysts for both the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) is critical for the widespread application of rechargeable zinc–air (Zn–air) batteries. This calls for rational screening of targeted ORR/OER components and precise control of their atomic and electronic structures to produce synergistic effects. Here, we report a Mn-doped RuO2 (Mn-RuO2) bimetallic oxide with atomic-scale dispersion of Mn atoms into the RuO2 lattice, which exhibits remarkable activity and super durability for both the ORR and OER, with a very low potential difference (ΔE) of 0.64 V between the half-wave potential of ORR (E 1/2) and the OER potential at 10 mA cm–2 (E j10) and a negligible decay of E 1/2 and E j10 after 250 000 and 30 000 CV cycles for ORR and OER, respectively. Moreover, Zn–air batteries using the Mn-RuO2 catalysts exhibit a high power density of 181 mW cm–2, low charge/discharge voltage gaps of 0.69/0.96/1.38 V, and ultralong lifespans of 15 000/2800/1800 cycles (corresponding to 2500/467/300 h operation time) at a current density of 10/50/100 mA cm–2, respectively. Theoretical calculations reveal that the excellent performances of Mn-RuO2 is mainly due to the precise optimization of valence state and d-band center for appropriate adsorption energy of the oxygenated intermediates.

fabricated. Combined with controlled synthesis, MOF materials are endowed with abundant various of structures, morphologies, and properties. [8-11] In addition, the as-prepared MOFs can be artificially modified via postsynthetic approaches utilizing their available pores and active sites of metal clusters or linkers. [12,13] As a result, not only the number of MOFs is further increased but also many interesting properties, such as high specific surface areas, tailorable pore sizes, modifiable structures, and properties are endowed with MOFs, which make them become potential candidates in storage/separation, catalysis, sensing, etc. [14,15] Another important application of MOFs is that they can act as conductive materials for electrocatalysis, sensing, and energy conversion, etc. [16-19] The existence of quantitative amounts of active metal centers, permanent porosity, and structural rigidity can facilitate surface contact and mass transfer as well as increase catalysis stability, making MOFs as ideal electrocatalysts. [20-22] In addition, they possess high specific surface areas, tunable bandgaps, and good charge transport properties, which extend their applications in sensing and energy storage. [23] Besides, the morphologies and characteristics of MOFs can be artificially modified to form 1D, 2D, or 3D structures via liquid phase selfassembly, physical/chemical exfoliation, layer-by-layer assembly, etc., promoting their applications in electrochemical devices and electronics. [24-26] With further structural design through postsynthesized modification, the performances of MOFs can be largely improved, facilitating their applications as conductive materials. [27-29] However, most MOFs are intrinsically electrically insulated, which seriously hinders their electrochemical applications. [29] The connected rigid metal ions and redox-inactive organic ligands increase the energy barrier for electron transfer, making them as electrical insulators. To overcome the drawbacks of MOFs, many feasible strategies have been adopted to promote the electron transfer in the structures of MOFs. [27,30-32] The high electrical conductivity of MOFs can be realized by integrating the conjugated planes or 1D chains in the structures, which relies on particular structural designs. [33-37] The conductivity of the MOFs can also be increased via doping with guest Metal-organic frameworks (MOFs) have aroused worldwide interest over the last two decades due to their various excellent properties, such as porosity, modifiability, stability, etc. Based on these unique features, they have been widely exploited for applications from electrocatalysis to electrochemical devices. However, most MOFs are inherently insulated due to the lack of free charge carriers and low-energy barriers for charge transfer, which largely restricts their further electrochemical applications. By imparting MOFs with electrical conductivity, their electrochemical process and catalysis efficiency can be effectively improved. Similarly, their applications in sensors, secon...

Single-atom catalysts with high activity and efficient atom utilization have great potential in the electrocatalysis field, especially for rechargeable zinc−air batteries (ZABs). However, it is still a serious challenge to rationally construct a single-atom catalyst with satisfactory electrocatalytic activity and long-term stability. Here, we simultaneously realize the atomic-level dispersion of cobalt and the construction of carbon nanotube (CNT)-linked N-doped porous carbon nanofibers (NCFs) via an electrospinning strategy. In this hierarchical structure, the Co−N 4 sites provide efficient oxygen reduction/evolution electrocatalytic activity, the porous architectures of NCFs guarantee the active site's accessibility, and the interior CNTs enhance the flexibility and mechanical strength of porous fibers. As a binder-free air cathode, the as-prepared catalysts deliver superdurability of 600 h at 10 mA cm −2 for aqueous ZABs and considerable flexibility and a small voltage gap for all-solid-state ZABs. This work provides an effective single-atom design/ nanoengineering for superdurable zinc−air batteries.

Nitrogen‐doped carbons are among the fastest‐growing class of materials used for oxygen electrocatalysis, namely, the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER), thanks to their low cost, environmental friendliness, excellent electrical conductivity, and scalable synthesis. The perspective of replacing precious metal‐based electrocatalysts with nitrogen‐doped carbon is highly desirable for reducing costs in energy conversion and storage systems. In this review, the role of nitrogen and N‐induced structural defects on the enhanced performance of N‐doped carbon electrocatalysts toward the OER and the ORR as well as their applications for energy conversion and storage technologies is summarized. The synthesis of N‐doped carbon electrocatalysts and the characterization of their nitrogen functional groups and active sites for the conversion of oxygen are also reviewed. The electrocatalytic performance of the main types of N‐doped carbon materials for OER/ORR electrocatalysis are then discussed. Finally, major challenges and future opportunities of N‐doped carbons as advanced oxygen electrocatalysts are highlighted.

This study proposes an NMR-based metabonomic approach to early prognostic evaluation of sepsis. Forty septic rats receiving cecal ligation and puncture (CLP) were divided into the surviving group and nonsurviving group on day 6, while 20 sham-operated rats served as the control group. Serum samples were collected from septic and sham-operated rats at 12 h after surgery and analyzed using (1)H NMR spectroscopy. Orthogonal partial least squares (OPLS) were applied and showed clustering according to predefined groups, indicating that NMR-based metabolic profiling could reveal pathologic characteristics in the serum of sham-operated, surviving, and nonsurviving septic rats. In addition, six characteristic metabolites including lactate, alanine, acetate, acetoacetate, hydroxybutyrate, and formate, which are mainly involved in energy metabolism, changed markedly in septic rats, especially in the nonsurvivors. Using these metabolites, a predictive model for prognostic evaluation of sepsis was constructed using a radial basis function neural network (RBFNN) with a prediction accuracy of about 87% by test samples. The results indicated that the NMR-based metabonomic approach is a potential technique for the early prognostic evaluation of sepsis.