competitive in comparison with other energy storage/conversion systems, such as fuel cells or lithium/sodium-ion batteries. [2] A typical ZAB stores and releases energy mainly through the redox reaction between the Zn anode and air cathode. The major challenge for air cathode is the large overpotentials due to the sluggish kinetics of oxygen reduction and evolution reactions (ORR/OER) during charging/ discharging processes. [3] To date, despite the satisfactory catalytic performance by state-of-the-art Pt-based and Ir/Ru-based catalysts, scalable and sustainable deployment of ZABs is severely impeded by the poor economic viability and low durability of these scarce precious metals. [4] Recently, single-atom catalysts (SACs) with M-N x /C moieties (M = Fe, Co, Ni, Mn) have attracted increasing attention as ORR and/or OER electrocatalysts due to their maximum atomic utilization, high intrinsic activity, and low cost. [5] Among the coordination structures, four pyridinic N-coordinated iron moiety in carbon matrix (Fe-N 4 /C) is one of the most potential catalytic sites for ORR since its more stable structure than other nitrogen coordination numbers and higher intrinsic activity than other central metal atoms. [6] Besides, the long-range interactions of other heteroatoms (such as S and P) from carbon supports are capable of tailoring local electronic structure of the Fe-N 4 /C moieties and carbon matrix, thereby promoting the adsorption and conversion of the ORR and/or OER intermediates at preferable reaction barriers. [7] Noble-metal-free, durable, and high-efficiency electrocatalysts for oxygen reduction and evolution reaction (ORR/OER) are vital for rechargeable Zn-air batteries (ZABs). Herein, a flexible and free-standing carbon fiber membrane immobilized with atomically dispersed Fe-N 4 /C catalysts (Fe/SNCFs-NH 3 ) is synthesized and used as air cathode for ZABs. The intertwined fibers with hierarchical nanopores facilitate the gas transportation, electrolyte infiltration and electron transfer. The large specific surface area exposes a high concentration of Fe-N 4 /C sites embedded in the carbon matrix. Modulation of local atomic configurations by sulfur doping in Fe/SNCFs-NH 3 catalyst leads to excellent ORR and enhanced OER activities. The as-synthesized Fe/ SNCFs-NH 3 catalyst demonstrates a positive half-wave potential of 0.89 V and a small Tafel slope of 70.82 mV dec -1 , outperforming the commercial Pt/C (0.86 V/94.74 mV dec -1 ) and most reported M-N x /C (M = Fe, Co, Ni) catalysts. Experimental characterizations and theoretical calculations uncover the crucial role of S doping in regulating ORR and OER activities. The liquid-state ZABs with Fe/SNCFs-NH 3 catalyst as air cathode deliver a large peak power density of 255.84 mW cm -2 and long-term cycle durability over 1000 h. Solidstate ZAB shows stable cycling at various flat/bent/flat states, demonstrating great prospects in flexible electronic device applications.The ORCID identification number(s) for the author(s) of this article can be found un...

Carbon is a simple, stable and popular element with many allotropes. The carbon family members include carbon dots, carbon nanotubes, carbon fibers, graphene, graphite, graphdiyne and hard carbon, etc. They can be divided into different dimensions, and their structures can be open and porous. Moreover, it is very interesting to dope them with other elements (metal or non‐metal) or hybridize them with other materials to form composites. The elemental and structural characteristics offer us to explore their applications in energy, environment, bioscience, medicine, electronics and others. Among them, energy storage and conversion are extremely attractive, as advances in this area may improve our life quality and environment. Some energy devices will be included herein, such as lithium‐ion batteries, lithium sulfur batteries, sodium‐ion batteries, potassium‐ion batteries, dual ion batteries, electrochemical capacitors, and others. Additionally, carbon‐based electrocatalysts are also studied in hydrogen evolution reaction and carbon dioxide reduction reaction. However, there are still many challenges in the design and preparation of electrode and electrocatalytic materials. The research related to carbon materials for energy storage and conversion is extremely active, and this has motivated us to contribute with a roadmap on ‘Carbon Materials in Energy Storage and Conversion’.

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Surface-enhanced Raman scattering (SERS) is a sensitive, fast, and nondestructive technology to detect trace amounts of molecules. The development of ultrasensitive and environmentally stable noble-metal-free SERS substrates is crucial for practical applications but still very challenging. In this contribution, an in situ substitutional doping strategy to synthesize Re-doped WSe 2 (Re-WSe 2 ) with different doping levels is reported. By increasing the Re content to ≈50 at%, the Re-WSe 2 alloy inherits the 1T″ phase of the ReSe 2 lattice. Furthermore, Nb atoms are doped into the 1T″ Re-WSe 2 alloy to further modulate its electronic structure. The as synthesized 1T″ Nb, Re-WSe 2 demonstrates a femtomolarlevel molecular sensing capability with a detectable concentration of 5 × 10 -15 m and the corresponding enhancement factor is 2.0 × 10 9 , which is superior to that of most non-noble-metal SERS substrates and comparable or even superior to that of noble-metal substrates to the best of the authors' knowledge. More importantly, the as-synthesized 1T″ Nb, Re-WSe 2 exhibits excellent air-stability over a long term (≈6 months) and selective detection capability in the mixed molecular solution, which are essential for their practical applications. The work provides a new strategy for the rational design of noble-metal-free SERS substrates to achieve ultrasensitive molecular sensing.

Developing efficient noble-metal-free surface-enhanced Raman scattering (SERS) substrates and unveiling the underlying mechanism is crucial for ultrasensitive molecular sensing. Herein, we report a facile synthesis of mixed-dimensional heterostructures via oxygen plasma treatments of two-dimensional (2D) materials. As a proof-of-concept, 1D/2D WO3-x/WSe2 heterostructures with good controllability and reproducibility are synthesized, in which 1D WO3-x nanowire patterns are laterally arranged along the three-fold symmetric directions of 2D WSe2. The WO3-x/WSe2 heterostructures exhibited high molecular sensitivity, with a limit of detection of 5 × 10−18 M and an enhancement factor of 5.0 × 1011 for methylene blue molecules, even in mixed solutions. We associate the ultrasensitive performance to the efficient charge transfer induced by the unique structures of 1D WO3-x nanowires and the effective interlayer coupling of the heterostructures. We observed a charge transfer timescale of around 1.0 picosecond via ultrafast transient spectroscopy. Our work provides an alternative strategy for the synthesis of 1D nanostructures from 2D materials and offers insights on the role of ultrafast charge transfer mechanisms in plasmon-free SERS-based molecular sensing.