Iron-chromium redox flow batteries (ICRFBs) have emerged as promising energy storage devices due to their safety, environmental protection, and reliable performance. The carbon cloth (CC), often used in ICRFBs as the electrode, provides a suitable platform for electrochemical processes owing to its high surface area and interconnected porous structure. However, the CC electrodes have issues, such as, insufficient electron transfer performance, which limits their industrial application. Here, we employed silicic acid etching to carve dense nano-porous structures on the surface of CC electrodes based on the favorable design of ICRFBs and the fundamental principles of electrode polarization losses. As a result, we developed a multifunctional carbon cloth electrode with abundant vacancies, notably enhancing the performance of the battery. The fabricated electrode showcased a wealth of defect sites and superior electronic transport properties, offering an extensive and effective reaction area for rapidly flowing electrolytes. With an electrode compression ratio of 40% and the highest current density in ICRFBs so far (140 mA·cm⁻²), the battery achieved the average energy efficiency of 81.3%, 11.24% enhancement over the previously published work. Furthermore, throughout 100 charge–discharge cycles, the average energy efficiency degradation was negligible (~ 0.04%), which has the potential to become the most promising candidate for large-scale and long-term electrochemical energy storage applications.

With the deployment of renewable energy and the increasing demand for power grid modernization, redox flow battery has attracted a lot of research interest in recent years. Among the available energy storage technologies, the redox flow battery is considered the most promising candidate battery due to its unlimited capacity, design flexibility, and safety. In this review, we summarize the latest progress and improvement strategies of common inorganic redox flow batteries, such as vanadium redox flow batteries, iron-chromium redox flow batteries, and zinc-based redox flow batteries, including electrolyte, membrane, electrode, structure design, etc. In addition, we introduce the latest progress in aqueous and non-aqueous organic redox flow batteries. We also focus on the modification mechanism, optimization design, improvement strategy, and modeling method of the redox flow battery reaction. Finally, this review presents a brief summary, challenges, and perspectives of the redox flow battery.

The two-dimensional quantum dots (2D-QDs) have been developed significantly in the past decades. The 2D-QDs could be used in bioimaging, biosensing, drug/gene delivery, and photodynamic/photothermal therapy. The potential applications in biology receive increasing attention, which makes them the novel and emerging candidates in biomaterial research fields. In this context, we discuss a variety of 2D-QDs with different physical and chemical properties. We focuse on the latest synthesis progress and recent applications in biotechnological, and biomedical applications of the 2D-QDs and we also evaluate the challenges and prospects in this field.

There is a high demand for hydrogels with multifunctional performance (a combination of adhesive, mechanical, and electrical properties) in biological, tissue engineering, robotics, and smart device applications. However, a majority of existing hydrogels are relatively rigid and brittle, with limited stretchability; this hinders their application in the emerging field of flexible devices. In this study, cheap and abundant potato residues were used with polyacrylamide (PAM) to fabricate a multifunctional hydrogel, and chitosan was used for the design of a three-dimentional (3D) network-structured hydrogel. The as-prepared hydrogels exhibited excellent stretchability, with an extension exceeding 900% and a recovery degree of over 99%. Due to the combination of physical and chemical cross-linking properties and the introduction of dopamine, the designed hydrogel exhibits a remarkable self-healing ability (80% mechanical recovery in 2 h), high tensile strength (0.75 MPa), and ultra-stretchability (900%). The resultant products offer superior properties compared to those of previously reported tough and self- healing hydrogels for wound adhesion. Chitosan and potato residues were used as scaffold materials for the hydrogels with excellent mechanical properties. In addition, in vitro experiments show that these hydrogels feature excellent antibacterial properties, effectively hindering the reproduction of bacteria. Moreover, the ternary hydrogel can act as a strain sensor with high sensitivity and a gauge factor of 1.6. The proposed strategy is expected to serve as a reference for the development of green and recyclable conductive polymers to fabricate hydrogels. The proposed hydrogel can also act as a suitable strain sensor for bio-friendly devices such as smart wearable electronic devices and/or for health monitoring.

The dual-emissive N, S co-doped carbon dots (N, S-CDs) with a long emission wavelength were synthesized via solvothermal method. The N, S-CDs possess relatively high photoluminescence (PL) quantum yield (QY) (35.7%) towards near-infrared fluorescent peak up to 648 nm. With the advanced characterization techniques including X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR), etc. It is found that the doped N, S elements play an important role in the formation of high QY CDs. The N, S-CDs exist distinct pH-sensitive feature with reversible fluorescence in a good linear relationship with pH values in the range of 1.0–13.0. What is more, N, S-CDs can be used as an ultrasensitive Ag⁺ probe sensor with the resolution up to 0.4 μM. This finding will expand the application of as prepared N, S-CDs in sensing and environmental fields.

Heteroatom-doped carbon dots (CDs) with a high photoluminescent quantum yield (PLQY) have recently attracted attention due to their applications in chemical sensors, photocatalysis, bioimaging, and drug delivery. Nitrogen and phosphorus are in close proximity to carbon in the periodic table and are key tracking elements in the field of biomedical imaging. These two elements alter the optical and electronic properties of CDs and help improve the fundamental understanding of their PLQY. This can also lead to multifunctional usage in photoimaging and photothermal therapy. However, most PLQYs resulting from the synthesis of P-doped CDs are currently below 50%. These CDs have limited usefulness in the fields of bioimaging and drug delivery. In this study, a single-step, high-efficiency hydrothermal method was applied to synthesize nitrogen and phosphorous-doped carbon dots ((N, P)-CDs) with a PLQY of up to 53.8% with independent emission behavior. Moreover, the CDs presented high monodispersity, robust excitation-independent luminescence, and stability over a large pH range. Spectroscopic investigations indicated that the PLQY of the (N, P)-CDs was primarily due to the addition of P and the passivation effect of the oxidized surface. The excellent fluorescence properties of (N, P)-CDs can be effectively and selectively quenched by Hg²⁺ ions. Such systems show a linear response in the 0–900 nM concentration range with a short response time, indicating their potential for applications in the fields of chemistry and biology.