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In recent years, there have been significant advancements in Al‐ion battery development, resulting in high voltage and capacity. Traditionally, only carbon‐based materials with layered structures and strong bonding capabilities can deliver superior performance. However, most other materials exhibited low discharge voltages of 1.4 V, especially in aqueous Al‐ion battery systems lacking anion intercalation. Thus, the development of high‐voltage cathode materials has become crucial. This study introduces 2D MoS2 as a high‐performance cathode for aqueous Al‐ion batteries. The material's interlayer structure enables the intercalation of AlCl4− anions, resulting in high‐voltage intercalation. The resulting battery achieved a high voltage of 1.8 V with a capacity of 750 mAh g−1, contributing to a high energy density of 890 Wh kg−1 and an impressive retention rate of ≈100% after 200 cycles. This research not only sheds light on the high‐voltage anion‐intercalation mechanism of MoS2 but also paves the way for the further development of advanced cathode materials in the field of Al‐ion batteries. By demonstrating the potential of using 2D MoS2 as a cathode material, this finding can lead to the development of more efficient and innovative energy storage technologies, ultimately contributing to a sustainable and green energy future. [ABSTRACT FROM AUTHOR]

Direct hydrogen fuel cells are generally heavy and rigid systems based on metal or plastic materials, which are not suitable for various miniwatt and flexible devices. In this study, we have developed a lightweight and flexible fuel cell based on paper substrate embedded with an Al foil inside, which is used as an in-situ hydrogen source by reaction with an electrolyte solution during operation. Benefited from the inhibited hydroxyl transportation by the porous cellulose network, the vigorous Al corrosion reaction is well controlled even though strong alkaline electrolyte is adopted, so that the fuel cell can be discharged for more than 5 hours at 1 mA cm-2 (0.83 V) with only 3.5 mg Al foil. The corresponding faradaic and energy efficiencies are as high as 72% and 18.3%, respectively. The fuel cell flexibility is also quite good when facing different bending angles. Considering its moderate power output, this flexible paper-based hydrogen fuel cell is especially suitable for powering various miniwatt and flexible devices, such as wearable electronics, biosensors, RFID tags, etc. However, higher power can be obtained by suitable stacking of the fuel cell.

Since direct solar energy conversion is considered to be crucial for the development of a sustainable society, photocatalytic hydrogen evolution has been extensively studied during the past few years. Despite the recent progress in solar-driven hydrogen evolution, photoactivity is still limited due to fast recombination of charge carriers and scaled production is hard to proceed with. The rational design of photocatalysts with spatially separated charge carriers has been shown to be one of the promising strategies for better photocatalyst charge separation efficiency. The spatial separation of photoinduced electrons and holes, as well as the rapid migration of electrons from the bulk to the reaction surface, results in suppressed charge recombination, prolongs the lifetime of photogenerated charges and blocks the backward reaction. In this review, the basic concepts of photocatalytic hydrogen production with heterojunction systems are introduced. Then, the rational designs of heterojunction photocatalyst systems to enable spatially separated reaction sites are summarized and categorized based on their dimensions and architectures. Finally, the outlook and research directions are discussed towards the set target of solar to hydrogen conversion efficiency and industrial production. [ABSTRACT FROM AUTHOR]

Summary: Lateral flow test assay requires integrated micro power sourcesto realize quantitative testing as well as to enhance accuracy. Conventional dry batteries generally havepollution issues for this task, while the recently emerged paper‐based fuel cells are both expensive and low‐voltage that restrict their usage. In comparison, the metal‐air battery (MAB) using a metal anode and an air‐breathing cathode could be a much better solution. In this study, different micro metal‐air batteries are integrated onto paper substrates, producing micro power sources that are low‐cost, high‐voltage and environmentally friendly. Their performances are compared under both alkaline and salt electrolytes in terms of power output, fabrication cost and specific energy. Among them, the Al‐air battery with an alkaline electrolyte and the Mg‐air battery with a salt electrolyte are more advantageous than others, achieving high voltage outputs of 1.55 V and 1.53 V at 1 mA cm−2, respectively. By using acarbon grid instead of asilver grid as current collector, and nitrogen‐doped carbon nanotubesinstead of MnO2 as oxygen reduction catalyst, the as‐fabricated micro MABs can be much cheaper and greener for disposable lateral flow test devices. Finally, a two‐cell micro Al‐air battery pack, which is integrated into a digital pregnancy tester, provides powersuccessfully for its operation for more than 5 minutes. [ABSTRACT FROM AUTHOR]

Aqueous Al–ion battery (AAIB) is regarded as a promising candidate for large‐scale energy storage systems due to its high capacity, high safety, and low cost, with MnO2 proved to be a high‐performance cathode. However, the potential commercial application of this type of battery is plagued by the frequent structural collapse of MnO2. Herein, an in situ, electrochemically reformed, urchin‐like AlxMnO2 cathode is developed for water‐in‐salt electrolyte‐based AAIBs. Benefiting from its unique α‐MnO2 coated Mn2AlO4 structure, a high Al ion storage capacity is achieved together with a high discharge voltage plateau of 1.9 V by reversible MnO2 electrolysis. Consequently, the battery exhibits a high specific capacity of 285 mAh g–1 and a high energy density of 370 Wh kg–1 at a high current density of 500 mA g–1. Improved stability with record capacity retention is also obtained at an ultrahigh current density of 5 A g–1 after 500 cycles. Such a high‐capacity and high‐stability AlxMnO2 cathode would pave the way for in situ electrochemical transformation of cathode design and thus boost the practical application of AAIBs. [ABSTRACT FROM AUTHOR]