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Single-atom catalysts (SACs) derived from metal–organic frameworks (MOFs) are revolutionizing electrocatalytic energy conversion. This review explores their synthesis, characterization, and application, emphasizing their role in advancing sustainable energy technologies. SACs offer unprecedented efficiency and selectivity by dispersing individual metal atoms on a support material. This maximizes active site utilization and minimizes material usage compared to traditional catalysts. Various synthesis strategies, such as bimetallic MOF pyrolysis and ligand-coordinated anchoring, enable precise control over SACs properties. Characterization techniques like electron microscopy and spectroscopy reveal SACs structures and properties. Electron microscopy visualizes SACs morphology, while spectroscopy provides insights into metal atom coordination. In practical applications, MOF-supported SACs excel in proton-exchange membrane fuel cells (PEMFCs), direct formic acid fuel cells (DFAFCs), and Zn–air batteries (ZABs). They catalyze essential reactions, such as oxygen reduction and hydrogen oxidation, enhancing PEMFC efficiency and durability. In ZABs, SACs improve oxygen reduction and evolution reactions, boosting battery performance and stability. This review underscores the potential of MOF-derived SACs in sustainable energy conversion. By detailing synthesis, characterization, and applications, it contributes to the development of efficient catalysts for renewable energy technologies. [ABSTRACT FROM AUTHOR]

Sodium ion batteries (SIBs) are considered as the ideal candidates for the next generation of electrochemical energy storage devices. The major challenges of anode lie in poor cycling stability and the sluggish kinetics attributed to the inherent large Na+ size. In this work, Bi nanosphere encapsulated in N‐doped carbon nanowires (Bi@N‐C) is assembled by facile electrospinning and carbonization. N‐doped carbon mitigates the structure stress/strain during alloying/dealloying, optimizes the ionic/electronic diffusion, and provides fast electron transfer and structural stability. Due to the excellent structure, Bi@N‐C shows excellent Na storage performance in SIBs in terms of good cycling stability and rate capacity in half cells and full cells. The fundamental mechanism of the outstanding electrochemical performance of Bi@N‐C has been demonstrated through synchrotron in‐situ XRD, atomic force microscopy, ex‐situ scanning electron microscopy (SEM) and density functional theory (DFT) calculation. Importantly, a deeper understanding of the underlying reasons of the performance improvement is elucidated, which is vital for providing the theoretical basis for application of SIBs. [ABSTRACT FROM AUTHOR]

Aqueous zinc–iodine batteries (Zn–I2) demonstrate great promise in large scale energy storage systems. However, their practical application faces significant challenges including dendrite formation, corrosion caused by polyiodine ions, and other side reactions at the zinc anode side. Herein, a facile and efficient pretreatment method for zinc anodes through the substitution reaction of Zn and SnF2 to create a dense and durable multifunctional surface layer (MSL). The MSL comprise tin (Sn) and ZnF2 phases on the zinc metal, in which Sn possesses good zinc affinity and a high hydrogen evolution overpotential, while ZnF2 provides pathways for radial ion transport. Importantly, both have a low binding energy with polyiodine ions, preventing the failure of the interface layer. Therefore, this interface layer can effectively mitigate zinc metal electrode dendrite formation, corrosion from polyiodine ions, and other side reactions induced by water, simultaneously. As a result, the Zn–I2 batteries performance is greatly improved and exhibited a stable cycling to 20 000 times with 80% capacity retention at a current density of 2 A g−1. Even the I2 loading is increased to 8 mg cm−2, it can still cycle stably for 5000 cycles with a capacity retention of 94%. [ABSTRACT FROM AUTHOR]

TiO2‐based materials are considered to be the promising anodes of sodium‐ion batteries (NIBs) because of their high safety and good stability. However, their low specific capacity and high safety operating voltage plateau impose a severe challenge for high energy density batteries. Herein, interconnected micro‐sheets consisting of carbon nanotubes and sulfur doped TiO2 (CNT/S‐TiO2) are synthesized via an ultrasonic process and subsequent calcination, enabling the fabrication of high‐performance material. The utilization of SWCNT overcomes the structure instabilities during electrode preparation of thick electrodes. The incorporation of SWCNT and sulfur dopants in the CNT/S‐TiO2 composite not only enhances conductivity but also improves ion transport dynamics, resulting in rapid charge delivery and high specific capacity at the thick electrode level. Consequently, CNT/S‐TiO2 demonstrates excellent rate performance (from 0.3 to 15 C, with 72.4% capacity retention) and long cycling stability (10000 cycles at a load of 1.96 mg cm−2). More importantly, the high S‐TiO2 content (90%) in the thick electrode (21.2 mg cm−2) achieves a high areal capacity retention of 3.4 mA h cm−2 after 100 cycles, which surpasses the actual application requirements. [ABSTRACT FROM AUTHOR]

Lithium–sulfur (Li-S) batteries are the most attractive candidates for next-generation large-scale energy storage because of their high theoretical energy density and the affordability of sulfur. However, most of the reported research primarily concentrates on low sulfur loading (below 2 mgs cm−2) cathodes using binders and traditional collectors, thus undermining the expected energy density. Herein, a N, O co-doped carbon nanotube (N, O-CNT) decorated wood framework (WF), denoted as WF-CNT, was designed as a free-standing sulfur host, achieving high sulfur loading of 10 mgs cm−2. This unique cathode featured low tortuosity microchannels and a conductive framework, reducing the diffusion paths for both ions and electrons and accommodating the volume changes associated with sulfur. Moreover, the internal CNT forests effectively captured soluble lithium polysulfides (LiPSs) and catalyze their redox kinetic. Consequently, the S@WF-CNT-800 sample exhibited a high initial discharge capacity of 1438.2 mAh g−1 at a high current density of 0.5 A g−1. Furthermore, a reversible capacity of 404.5 mAh g−1 was obtained after 500 cycles with sulfur loading of 5 mgs cm−2 at 0.5 A g−1. This work may support the development of high sulfur loading cathodes utilizing cost-effective and sustainable biomass materials for Li-S batteries. [ABSTRACT FROM AUTHOR]