SMALL STRUCTURES

The use of graphite anode renders practical lithium‐ion batteries for effective energy storage. However, graphite anode is the bottleneck to achieve the fast charging of a battery, ascribed to its low operating potential and corresponding incidental lithium plating. Herein the principle of a thin nanoscale layer on the graphite surface to improve charging capability is investigated by applying a three‐electrode device to precisely record the working behavior. The Li⁺ diffusion rate is significantly improved by coating a nanoscale turbostratic carbon layer, in which abundant active sites and additional fast Li⁺ diffusion pathways at the basal‐plane side of graphite sheets render small polarization in a working battery. This fresh understanding enriches the fundamental insights into enhancing the rate performance and facilitating the practical applications of graphite in fast‐charging batteries.

Developing high‐performance, low‐cost, and robust electrocatalysts is of great importance to boost the efficiency of oxygen evolution reaction (OER). Herein, based on the integrated design of chemical composition and geometric structure, Fe‐doped CoO nanotubes (NTs) with high OER activity are prepared by a facile template‐free approach. The construction of this tubular structure is realized via a simple wet‐chemical reaction to prepare solid nanorods as precursor and a subsequent calcination treatment of the precursor to form hollow cavity. The favorable composition and unique hollow structure endow these Fe‐doped CoO NTs with remarkable activity toward OER. When used as the electrocatalyst for OER, the Fe‐doped CoO NTs show a small overpotential of 282 mV at the current density of 10 mA cm⁻², a low Tafel slope of 78.26 mV dec⁻¹, and a high turnover frequency of 0.0965 s⁻¹ at the overpotential of 282 mV, which is superior to those of CoO NTs and solid CoO nanoparticles. Moreover, the Fe‐doped CoO NTs also exhibit excellent long‐term stability of 24 h at the current density of 10 mA cm⁻².

Rechargeable Zn−air batteries (ZABs) have attracted increasing attention as one of the most promising future energy power sources due to their relatively high specific energy density, environmental friendliness, safety, and low cost. In particular, flexible ZABs are desirable for portable and wearable electronic devices, in which the cathode can utilize air directly from the atmosphere with significantly enhanced energy density. Therefore, the air electrode consisting of oxygen electrocatalysts is the most critical component in flexible ZABs, significantly governing the overall battery performance and cost. This review highlights recent achievements in designing efficient oxygen electrocatalysts and air electrodes for rechargeable and flexible ZABs. First, the most significant innovations of recent battery configurations to improve flexibility and battery performance are introduced. Then, oxygen electrocatalysts developed for fabricating high‐performance air cathodes in flexible ZABs in terms of catalyst properties, unique nanostructures, and morphologies are emphasized. Furthermore, effective architectures of air electrodes are discussed to highlight structural stability and charge/mass transports for improving battery performance. Finally, a perspective for designing durable and high‐power air electrodes for flexible ZABs is provided, aiming to summarize current challenges and possible solutions to commercialize the exciting battery technology eventually.

Electrochemical water splitting, as a promising sustainable‐energy technology, has been limited by its slow kinetics and large overpotential. This shortcoming necessitates the design of 1D nanocatalysts with large surface area, high electronic conductivity, and easily tunable composition. Herein, recent progress about electrocatalytic water splitting based on the advanced electrospun nanomaterials is reviewed. First, the related fundamentals of electrochemical water splitting according to two main aspects are discussed as follows: hydrogen evolution reaction and oxygen evolution reaction. Second, the structure design and the electrocatalytic properties of electrospun nanomaterials according to difference in component (including single metal‐based electrocatalysts, metal alloy‐based electrocatalysts, metal oxide‐based electrocatalysts, metal sulfide‐based electrocatalysts, metal phosphide‐based electrocatalysts, metal carbide‐based electrocatalysts, etc.) are summarized. Finally, the future perspectives and challenges for designing next‐generation 1D electrospun nanocatalysts for electrochemical water splitting are concluded.

Wearable multimodal sensors could enable the continuous, non‐invasive, precise monitoring of vital human signals critical for remote health monitoring and telemedicine. Atomically thin materials with intriguing physical characteristics, rich chemistry, and extreme sensitivity to external stimuli are attractive for implementing high‐performance wearable sensors. Despite the increased interest and efforts in 2D materials‐based wearable sensors, reducing the manufacturing and integration costs while improving the product performance remains challenging. Previous review articles provided good coverage discussing the material and device aspects of 2D materials‐based wearable devices. However, few reviews discussed the status quo, prospects, and opportunities for the scalable nanomanufacturing of 2D materials wearable sensors for health monitoring. To fill this gap, the recent advances in 2D materials‐based wearable health sensors are reviewed. The structure design, fabrication processing, the mechanisms of 2D materials‐based wearable health sensors, and their applications for human health monitoring are discussed. More significantly, a systematic discussion of the state‐of‐the‐art and technological gaps for enabling future design and nanomanufacturing of 2D materials wearable health sensors are provided. Finally, the challenges and opportunities associated with the scalable nanomanufacturing of 2D wearable health sensors are discussed.

Photocatalytic CO₂ reduction attracts substantial interests for the production of chemical fuels via solar energy conversion, but the activity, stability, and selectivity of products were severely determined by the efficiencies of light harvesting, charge migration, and surface reactions. Structural engineering is a promising tactic to address the aforementioned crucial factors for boosting CO₂ photoreduction. Herein, a timely and comprehensive review focusing on the recent advances in photocatalytic CO₂ conversion based on the design strategies over nano‐/microstructure, crystalline and band structure, surface structure and interface structure is provided, which covers both the thermodynamic and kinetic challenges in CO₂ photoreduction process. The key parameters essential for tailoring the size, morphology, porosity, bandgap, surface, or interfacial properties of photocatalysts are emphasized toward the efficient and selective conversion of CO₂ into valuable chemicals. New trends and strategies in the structural design to meet the demands for prominent CO₂ photoreduction activity are also introduced. It is expected to furnish a comprehensive guideline for inside‐and‐out design of state‐of‐the‐art photocatalysts with well‐defined structures for CO₂ conversion.

Lithium–sulfur (Li–S) batteries have attracted intensive attention due to their high energy density and low cost. However, Li–S batteries are still confronted with the challenges of low sulfur utilization, short cycle life, and unsatisfactory Coulombic efficiency. Free‐standing nanostructured architectures often have tunable features, such as strong mechanical properties, high electrical conductivity, and abundant porous structures, endowing them with the ability to serve as sulfur hosts, functional interlayers on separators, as well as lithium matrices. Herein, the electrochemical principles of Li–S batteries and the motivation for designing free‐standing architectures for sulfur cathodes, functional separators, and lithium anode protection are described. Furthermore, the recent progress on free‐standing sulfur cathodes based on carbon nanotubes, graphene, and MXenes is summarized in detail. In addition, the design of free‐standing nanostructured architectures in functional separators and lithium anode protection is also presented. Finally, future developments and prospects in the design of free‐standing architectures for Li–S batteries are discussed.

Significant efforts have been made on cancer control by scientists. And various methods for cancer treatment are constantly emerging. Among them, photothermal therapy (PTT) has received a wide range of attention due to its special features, including noninvasiveness, remote control, high selectivity, negligible drug resistance, insignificant side effects, and desired therapeutic effects. Photothermal agents (PTAs), which can convert light into heat under laser irradiation, serve as a crucial role during PTT for killing cancer cells. In the past decades, different kinds of PTAs have been successfully developed. Among these, polymer‐based PTAs are widely used in cancer diagnosis and PTT owing to their competitive features, including customizable designs, controllable synthesis, excellent biocompatibility, negligible cytotoxicity, satisfactory photostability, and desirable photothermal effects. In addition, along with PTT, they also play a crucial role in tumor targeting, cancer imaging, drug delivery, and combination therapies. Herein, the recent advances in cancer therapeutic nanoplatforms built on polymers are reviewed in detail. Meanwhile, future opportunities and challenges for polymer‐based PTAs in cancer therapy are also exemplified.

A functional substrate with heterogeneous wettability elaborately integrates the water loving and repellent properties onto an individual surface. Compared with homogeneous surfaces, nonuniformity in wettability endows a heterogeneous surface with a more remarkable capability for manipulation of the solid–liquid–gas interactions, which contributes to the progress and innovation in various applications, such as device fabrication, biological screening, and sample analysis. Recently, the development in microfabrication techniques has greatly promoted the versatility and diversity in the design and fabrication of substrates with high‐precision and high‐resolution heterogeneous wettability. In this review, the general principle of liquid manipulation using heterogeneous wettability surfaces is discussed. Then, the construction methodology of substrates with heterogeneous wettability surfaces is outlined in the order of chemical modification and physical engineering. Typical applications focused on optic/electronic device fabrication and biosensing/detection are summarized. Finally, current challenges and research prospects to enhance the practicality and universality of heterogeneous wettability substrates are also proposed.