Potassium ion energy storage devices are competitive candidates for grid-scale energy storage applications owing to the abundancy and cost-effectiveness of potassium (K) resources, the low standard redox potential of K/K+, and the high ionic conductivity in K-salt-containing electrolytes. However, the sluggish reaction dynamics and poor structural instability of battery-type anodes caused by the insertion/extraction of large K+ ions inhibit the full potential of K ion energy storage systems. Extensive efforts have been devoted to the exploration of promising anode materials. This Review begins with a brief introduction of the operation principles and performance indicators of typical K ion energy storage systems and significant advances in different types of battery-type anode materials, including intercalation-, mixed surface-capacitive-/intercalation-, conversion-, alloy-, mixed conversion-/alloy-, and organic-type materials. Subsequently, host–guest relationships are discussed in correlation with the electrochemical properties, underlying mechanisms, and critical issues faced by each type of anode material concerning their implementation in K ion energy storage systems. Several promising optimization strategies to improve the K+ storage performance are highlighted. Finally, perspectives on future trends are provided, which are aimed at accelerating the development of K ion energy storage systems.

Reduced graphene oxide (rGO) nanosheets decorated with gold nanoparticles (Au NPs/rGO), palladium nanoparticles (Pd NPs/rGO), and gold-palladium bimetallic nanoparticles (Au-Pd NPs)/rGO are synthesized by a simple solution chemistry approach using ascorbic acid as ecofriendly reducing agent. These materials are characterized by high resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and thermogravimetric analysis (TGA). The as-prepared nanocomposites are tested as electrocatalysts for efficient hydrogen evolution in deaerated 0.5 M H 2 SO 4 aqueous solution using polarization and impedance measurements. Experimental findings show that the tested catalysts exhibit fast hydrogen evolution kinetics with onset potentials as low as −17, −7.2, and −0.8 mV vs. RHE for Au NPs/rGO, Pd NPs/rGO, and Au-Pd NPs/rGO, respectively. In addition, Tafel slopes of 39.2, 33.7 and 29.0 mV dec -1 and exchange current densities of 0.09, 0.11, and 0.47 mA cm -2 are measured for Au NPs/rGO, Pd NPs/rGO, and Au-Pd NPs/rGO, respectively. The tested materials not only maintain their high performance after 5000 sweep cycles, but their activity is simultaneously enhanced after this aging process. These findings reveal that the tested catalysts, particularly Au-Pd NPs/rGO, are promising candidates among other noble metal catalysts for hydrogen evolution, approaching the commercial Pt/C catalyst (onset potential: 0.0 mV, Tafel slope: 31 mV dec -1 , and exchange currrent density: 0.78 mA cm -2 ). The high hydrogen evolution reaction (HER) activity of such materials is likely due to the abundance of active catalytic sites, the increased electrochemically accessible surface area and significantly improved electrochemical conductivity.

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Metal–organic frameworks (MOFs) have potential applications in removing pollutants such as heavy metals, oils, and toxins from water. However, due to the intrinsic fragility of MOFs and their fine powder form, there are still technical barriers to their practical application such as blockage of pipes, difficulty in recovery, and potential environmental toxicity. Therefore, attention has focused on approaches to convert nanocrystalline MOFs into macroscopic materials to overcome these limitations. Recently, strategies for shaping MOFs into beads (0D), nanofibers (1D), membranes (2D), and gels/sponges (3D) with macrostructures are developed including direct mixing, in situ growth, or deposition of MOFs with polymers, cotton, foams or other porous substrates. In this review, successful strategies for the fabrication of macroscopic materials from MOFs and their applications in removing pollutants from water including adsorption, separation, and advanced oxidation processes, are discussed. The relationship between the macroscopic performance and the microstructure of materials, and how the range of 0D to 3D macroscopic materials can be used for water treatment are also outlined.

Cutting-edge technologies are making inroads into new areas and this remarkable progress has been successfully influenced by the tiny level engineering of carbon dots technology, their synthesis advancement and impressive applications in the field of allied sciences. The advances of science and its conjugation with interdisciplinary fields emerged in carbon dots making, their controlled characterization and applications into faster, cheaper as well as more reliable products in various scientific domains. Thus, a new era in nanotechnology has developed into carbon dots technology. The understanding of the generation process, control on making processes and selected applications of carbon dots such as energy storage, environmental monitoring, catalysis, contaminates detections and complex environmental forensics, drug delivery, drug targeting and other biomedical applications, etc., are among the most promising applications of carbon dots and thus it is a prominent area of research today. In this regard, various types of carbon dot nanomaterials such as oxides, their composites and conjugations, etc., have been garnering significant attention due to their remarkable potential in this prominent area of energy, the environment and technology. Thus, the present paper highlights the role and importance of carbon dots, recent advancements in their synthesis methods, properties and emerging applications.

Controlling the morphology, composition, and crystalline phase of mesoporous nonnoble metal catalysts is essential for improving their performance. Herein, well‐defined P‐ and B‐codoped NiFe alloy mesoporous nanospheres (NiFeB‐P MNs) with an adjustable Ni/Fe ratio and large mesopores (11 nm) are synthesized via soft‐template‐based chemical reduction and a subsequent phosphine‐vapor‐based phosphidation process. Earth‐abundant NiFe‐based materials are considered promising electrocatalysts for the oxygen evolution reaction (OER) because of their low cost and high intrinsic catalytic activity. The resulting NiFeB‐P MNs exhibit a low OER overpotential of 252 mV at 10 mA cm−2, which is significantly smaller than that of B‐doped NiFe MNs (274 mV) and commercial RuO2 (269 mV) in alkaline electrolytes. Thus, this work highlights the practicality of designing mesoporous nonnoble metal structures and the importance of incorporating P in metallic‐B‐based alloys to modify their electronic structure for enhancing their intrinsic activity.

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