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.

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This review gives a systematic discussion on the synthetic methodologies of 2D MOF-based materials for electrocatalysis applications.

Designing high-performance trifunctional electrocatalysts for ORR/OER/HER with outstanding activity and stability for each reaction is quite significant yet challenging for renewable energy technologies. Herein, a highly efficient and durable trifunctional electrocatalyst RuCoO x is prepared by a unique one-pot glucose-blowing approach. Remarkably, RuCoO x catalyst exhibits a small potential difference (ΔE) of 0.65 V and low HER overpotential of 37 mV (10 mA cm −2 ), as well as a negligible decay of overpotential after 200 000/10 000/10 000 CV cycles for ORR/OER/HER, all of which show overwhelming superiorities among the advanced trifunctional electrocatalysts. When used in liquid rechargeable Zn−air batteries and water splitting electrolyzer, RuCoO x exhibits high efficiency and outstanding durability even at quite large current density. Such excellent performance can be attributed to the rational combination of targeted ORR/OER/HER active sites into one electrocatalyst based on the double-phase coupling strategy, which induces sufficient electronic structure modulation and synergistic effect for enhanced trifunctional properties.

Transition metal oxides (TMOs) are promising inorganic electrochromic materials (ECMs) that can be widely used in electronic displays and adaptive camouflage. However, there are still huge challenges for TMOs to simultaneously achieve multicolor transformation capability and good cycling stability. Herein, we assemble Au-modified (0.01 wt %) V x O 2x+1 (x > 2) nanoflowers (Au@V x O 2x+1 NFs) composed of two-dimensional porous nanosheets containing two valences states of vanadium (V 4+ and V 5+ ). The Au@V x O 2x+1 NFs exhibits outstanding electrochromic performance with five reversible color transformations (orange, yellow, green, gray, and blue) at a voltage less than 1.5 V and excellent cycling stability (2000 cycles without significant decay). To the best of our knowledge, this is the first time that a single vanadium oxide ECM, rather than a device, realizes five color changes. This work provides a feasible way for the efficient preparation of multicolor electrochromic TMOs. The newly developed Au@V x O 2x+1 NFs demonstrate the potential application in adaptive camouflage.

Reducing energy consumption is one of the major concerns in modern building design and construction because buildings account for ≈40% of the total energy consumption in modern society. Among various technologies for saving energy, electrochromic smart windows are considered as a highly promising one. Except for the application in saving energy, electrochromism has also attracted extensive attention in many other fields, such as, anti‐glare rearview mirrors, displays, military camouflage, flexible wearable fabric, etc. However, there are still many challenges needed to be solved, such as, the response rate and durability of electrochromic materials (ECMs). The transmission rate of ions in ECMs determines the response rate of the whole electrochromic device. Besides, the embedding depth and total amount of ions directly affect the contrast, durability, and coloration efficiency of ECMs. It is crucial to select suitable electrolyte ions to obtain high‐efficiency ECMs. Here, the challenges in ECMs based on ions insertion/extraction are presented, which are focused on advanced nanostructured ECMs’ design and electrochromic devices’ practical application. Recent advances in ECMs are presented to discuss the important questions, which are especially focused on the connection between suitable ions and advanced nanostructural ECMs. Finally, a perspective for next‐generation electrochromic devices is presented.