Owing to their tunable direct bandgap, high charge carrier mobility, and unique in‐plane anisotropic structure, black phosphorus nanosheets (BPNSs) have emerged as one of the most important candidates among the 2D materials beyond graphene. However, the poor ambient stability of black phosphorus limits its practical application, due to the chemical degradation of phosphorus atoms to phosphorus oxides in the presence of oxygen and/or water. Chemical functionalization is demonstrated as an efficient approach to enhance the ambient stability of BPNSs. Herein, various covalent strategies including radical addition, nitrene addition, nucleophilic substitution, and metal coordination are summarized. In addition, efficient noncovalent functionalization methods such as van der Waals interactions, electrostatic interactions, and cation–π interactions are described in detail. Furthermore, the preparations, characterization, and diverse applications of functionalized BPNSs in various fields are recapped. The challenges faced and future directions for the chemical functionalization of BPNSs are also highlighted.

Benefiting from the merits of low cost, nonflammability, and high operational safety, aqueous rechargeable batteries have emerged as promising candidates for large‐scale energy‐storage applications. Among various metal‐ion/non‐metallic charge carriers, the proton (H⁺) as a charge carrier possesses numerous unique properties such as fast proton diffusion dynamics, a low molar mass, and a small hydrated ion radius, which endow aqueous proton batteries (APBs) with a salient rate capability, a long‐term life span, and an excellent low‐temperature electrochemical performance. In addition, redox‐active organic molecules, with the advantages of structural diversity, rich proton‐storage sites, and abundant resources, are considered attractive electrode materials for APBs. However, the charge‐storage and transport mechanisms of organic electrodes in APBs are still in their infancy. Therefore, finding suitable electrode materials and uncovering the H⁺‐storage mechanisms are significant for the application of organic materials in APBs. Herein, the latest research progress on organic materials, such as small molecules and polymers for APBs, is reviewed. Furthermore, a comprehensive summary and evaluation of APBs employing organic electrodes as anode and/or cathode is provided, especially regarding their low‐temperature and high‐power performances, along with systematic discussions for guiding the rational design and the construction of APBs based on organic electrodes.

Developing high‐performance visible‐to‐UV photon upconversion systems based on triplet–triplet annihilation photon upconversion (TTA‐UC) is highly desired, as it provides a potential approach for UV light‐induced photosynthesis and photocatalysis. However, the quantum yield and spectral range of visible‐to‐UV TTA‐UC based on nanocrystals (NCs) are still far from satisfactory. Here, three different sized CdS NCs are systematically investigated with triplet energy transfer to four mediators and four annihilators, thus substantially expanding the available materials for visible‐to‐UV TTA‐UC. By improving the quality of CdS NCs, introducing the mediator via a direct mixing fashion, and matching the energy levels, a high TTA‐UC quantum yield of 10.4% (out of a 50% maximum) is achieved in one case, which represents a record performance in TTA‐UC based on NCs without doping. In another case, TTA‐UC photons approaching 4 eV are observed, which is on par with the highest energies observed in optimized organic systems. Importantly, the in‐depth investigation reveals that the direct mixing approach to introduce the mediator is a key factor that leads to close to unity efficiencies of triplet energy transfer, which ultimately governs the performance of NC‐based TTA‐UC systems. These findings provide guidelines for the design of high‐performance TTA‐UC systems toward solar energy harvesting.

Aqueous ammonium‐ion (NH ₄ ⁺ ) batteries (AAIBs) have recently been considered as attractive alternatives for next‐generation large‐scale energy storage systems, on account of their cost‐effectiveness, nonflammability, less corrosive, small hydrated ionic radius, and rapid NH ₄ ⁺ diffusion kinetics. In addition, the tetrahedral structure of NH ₄ ⁺ exhibits preferential orientation characteristics, resulting in a different electrochemical storage mechanism from spherical charge carriers such as Li ⁺ , Na ⁺ , and K ⁺ . Therefore, unlocking the NH ₄ ⁺ ‐ion storage mechanisms in host electrode materials is pivotal to advancing the design of high‐performance AAIBs. Organic materials, with their customizable, flexible, and stable molecular structures, along with their ease of recycling and disposal, offer tremendous potential. However, the development of cutting‐edge organic electrode materials specifically for ammonium‐ion storage in AAIBs remains an exciting, yet largely untapped, frontier. This review systematically explores the interaction mechanisms between NH ₄ ⁺ ions and organic electrode materials, such as electrostatic interactions including hydrogen bonding. It also highlights the application of diverse organic electrode materials, such as small molecules, conducting polymers, covalent organic frameworks (COFs), and organic‐inorganic hybrids in AAIBs. Lastly, the review addresses the key challenges and future perspectives of organic‐material‐based AAIBs, aiming to push the boundaries of cutting‐edge aqueous energy storage systems.