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The aprotic lithium‐oxygen (Li−O2) battery with a high theoretical energy density has been considered as a promising candidate for next‐generation energy storage devices. However, the formation of insulating Li2O2 products is a major obstacle for realizing the high energy efficiency and long cycle life. Here, we report a new Cl−/Cl3− redox mediator to reduce the charge overpotential by a facile introduction of chloride ion (Cl−) additives into the organic electrolyte. The redox mediator can effectively promote the formation of the LiOH discharge product, and facilitate efficient LiOH decomposition. Therefore, the cell with the Cl− additives possesses a significantly low charge overpotential of 0.29 V, an extended cycle life (up to 71 cycles) at a rate of 500 mA g−1 with a fixed capacity of 500 mAh g−1, and an enhanced rate capability. This study offers an effective approach to modulate discharge products from Li2O2 to LiOH and provides new insights toward the role of redox mediators through the addition of Cl− in Li−O2 battery systems. [ABSTRACT FROM AUTHOR]

Alumina (Al2O3) microfiltration membranes with holey interior structure exhibit the combined desirable properties of both superior permeability and good retention performance. These membranes are purposely made to consist of a holey intermediate layer with a thickness in the range 12.9‐15.5 μm and a top filtration layer of very thin thickness in the range 1.8‐2.8 μm, fabricated by cosintering with sacrificial carbon (C) particles. The holey structure in the intermediate layer, which can be well controlled by regulating the amount of C particles added to Al2O3 particles, contains plenty of holes of 1‐5 μm in size, thereby possessing much reduced water flow resistance. The thin top filtration layer, which contains uniformly distributed nanopores of 90‐100 nm in size, functions as the selective layer, thereby ensuring a good retention performance. At the C particle content of 30 wt. %, the Al2O3 membrane with holey interior structure demonstrates a super‐high pure water flux (3358 Lm‐2h‐1), which is almost twice that of the membrane without holey interior structure (1697 Lm‐2h‐1), while the mechanical strength and retention performance are well maintained. [ABSTRACT FROM AUTHOR]

Li–O2 batteries represent a promising candidate for next-generation energy storage systems because of their high specific energy density. However, one key limitation is their low energy efficiency, which is caused by the high charge overpotential owing to the sluggish oxidation kinetics of the insulating Li2O2 product. Here, we report an approach to reduce charge overpotentials by forming Na-doped defective Li2O2 in a Na+-added electrolyte, which is verified by systematic experimental characterization. Theoretical simulations reveal that the Na-doped Li2O2 with lithium vacancies exhibits new conducting states right above the valence band edge, thereby enhancing electron transport properties. The cell with the defective-Li2O2 product achieves a charge overpotential of ∼0.4 V, much lower than that of the cell with Li2O2 (∼1.1 V). This study offers an effective approach to promote Li2O2 decomposition by forming defective Li2O2. [ABSTRACT FROM AUTHOR]

Rechargeable non-aqueous Li–O2 batteries show great potential as an attractive energy storage system due to their ultrahigh theoretical energy density. However, their commercial application is restricted by the large charge overpotential originating from the low conductivity of the discharge product, which thereby results in poor cycle performance. Herein, we develop Co3O4 functionalized porous carbon nanotubes (p-CNT/Co3O4) as an efficient cathode catalyst for Li–O2 batteries. The abundant pore structures of p-CNT can facilitate efficient Li+ and O2 diffusion and provide more buffer interfaces to accommodate the discharge product Li2O2, leading to a high capacity. The functionalization of Co3O4 on the p-CNT surface can significantly enhance the O2 adsorption on the cathode surface and the formation of thin-film Li2O2 proceeds with the surface growth mode, thereby achieving a low charge overpotential. At a current density of 100 mA g−1, the p-CNT/Co3O4 shows an initial discharge capacity of 4331 mA h g−1 with a reduced overpotential of 0.95 V, and is able to work for 116 cycles at 200 mA g−1 with a fixed capacity of 500 mA h g−1. [ABSTRACT FROM AUTHOR]

Aprotic Li–O2 batteries represent promising alternative devices for electrical energy storage owing to their extremely high energy densities. Upon discharge, insulating solid Li2O2 forms on cathode surfaces, which is usually governed by two growth models, namely the solution model and the surface model. These Li2O2 growth models can largely determine the battery performances such as the discharge capacity, round-trip efficiency and cycling stability. Understanding the Li2O2 formation mechanism and controlling its growth are essential to fully realize the technological potential of Li–O2 batteries. In this review, we overview the recent advances in understanding the electrochemical and chemical processes that occur during the Li2O2 formation. In the beginning, the oxygen reduction mechanisms, the identification of O2−/LiO2 intermediates, and their influence on the Li2O2 morphology have been discussed. The effects of the discharge current density and potential on the Li2O2 growth model have been subsequently reviewed. Special focus is then given to the prominent strategies, including the electrolyte-mediated strategy and the cathode-catalyst-tailoring strategy, for controlling the Li2O2 growth pathways. Finally, we conclude by discussing the profound implications of controlling Li2O2 formation for further development in Li–O2 batteries. [ABSTRACT FROM AUTHOR]

Developing an efficient cathode is essential to obtain high rate capability and rechargeable lithium oxygen (Li-O2 ) batteries. Herein, ruthenium (Ru)-functionalized hierarchical carbon nanocages (hCNCs) are synthesized and employed as a cathode catalyst for Li-O2 batteries. The as-prepared cathode exhibits high discharge capacity, low charge potential (8135 mAhg-1 with 3.85V charge potential at a current density of 0.08 mAcm-2 ), outstanding rate capability (3416 mAhg-1 at a current density of 0.48 mAcm-2 ) and good stability up to 78 cycles at a limited capacity of 500 mAhg-1 . Such excellent battery performance is ascribed to the synergistic effect of the interconnected hierarchically porous structure of hCNCs, which can facilitate effective electrolyte immersion and efficient Li-O2 mass transport, and the high catalytic activity of Ru nanoparticles. [ABSTRACT FROM AUTHOR]

Rechargeable Li–O2 batteries with remarkably high theoretical energy densities have attracted extensive attention. However, to enable Li–O2 batteries for practical applications, numerous challenges need to be overcome, e.g. high overpotential, low rate capability, and poor cycling stability. The key factor to tackle these issues is to develop highly-efficient cathode catalysts. Moreover, cathode catalysts with a porous structure and large surface area are favorable in Li–O2 batteries. In this paper, hierarchical porous Co3O4 nanoboxes with well-defined interior voids, functional shells and a large surface area have been facilely synthesized via an ion exchange reaction between Prussian blue analogue nanocubic precursors and OH− at a low temperature (60 °C). The obtained products possess hierarchical pore sizes and an extremely large surface area (272.5 m2 g−1), which provide more catalytically active sites to promote the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) as a Li–O2 battery cathode, as well as facilitating the diffusion of oxygen and the electrolyte. The hierarchical porous Co3O4 nanobox cathode shows enhanced discharge capacity, reduced overpotential, improved rate performance and cycle stability, in comparison with the EC-300J carbon cathode. The superb performance of the hierarchical porous Co3O4 nanoboxes, together with the facile fabrication approach, presents an alternative method to develop advanced cathode catalysts for Li–O2 batteries. [ABSTRACT FROM AUTHOR]

Covalent triazine frameworks (CTFs), noted for their rich nitrogen content, have attracted significant attention as promising photocatalysts. However, the structural complexity introduced by the diversity of nitrogen atoms in nitrogen‐rich CTFs poses a substantial challenge in discovering high‐performance CTFs. To address this challenge, a machine‐learning approach is developed to rationally design nitrogen‐rich CTFs, which is subsequently validated through experimental methods. A framework is employed based on the special orthogonal group in three dimensions (SO(3))‐invariant graph neural networks to predict photocatalytic properties of CTFs structures. This approach achieves exceptionally high accuracies with R2 scores exceeding 0.98. From a dataset of 14920 CTFs structures, this framework identifies 45 high‐performance candidates. Guided by these predictions, a novel CTF structure, pyridine‐2,5‐dicarbaldehyde (CTF‐DCPD) is selected and successfully synthesized, which exhibits an ultrahigh hydrogen evolution rate of 17.70 mmol g−1 h−1. This rate significantly surpasses that of the widely studied CTF‐1,4‐dicyanobenzene (CTF‐DCB, 10.41 mmol g−1 h−1). This work provides a new paradigm for machine learning to accelerate materials development, which can be generalized to the development of other functional materials. [ABSTRACT FROM AUTHOR]

Aprotic Li–O2 batteries are promising candidates for next‐generation energy storage technologies owing to their high theoretical energy densities. However, their practically achievable specific energy is largely limited by the need for porous conducting matrices as cathode support and the passivation of cathode surface by the insulating Li2O2 product. Herein, a self‐standing and hierarchically porous carbon framework is reported with Co nanoparticles embedded within developed by 3D‐printing of cobalt‐based metal–organic framework (Co‐MOF) using an extrusion‐based printer, followed by appropriate annealing. The novel self‐standing framework possesses good conductivity and necessary mechanical stability, so that it can act as a porous conducting matrix. Moreover, the porous framework consists of abundant micrometer‐sized pores formed between Co‐MOF‐derived carbon flakes and meso‐ and micropores formed within the flakes, which together significantly benefit the efficient deposition of Li2O2 particles and facilitate their decomposition due to the confinement of insulating Li2O2 within the pores and the presence of Co electrocatalysts. Therefore, the self‐standing porous architecture significantly enhances the cell's practical specific energy, achieving a high value of 798 Wh kg−1cell. This study provides an effective approach to increase the practical specific energy for Li–O2 batteries by constructing 3D‐printed framework cathodes. 3D‐printed cobalt (Co)‐based metal–organic framework–derived carbon framework with a hierarchically porous network and embedded with Co nanocatalysts is developed via a extrusion‐based method. The self‐standing framework acts as a porous conducting matrix for the cathode, and the desired micrometer‐sized pores formed between carbon flakes efficiently accumulate Li2O2 particles, which together significantly increases the practical specific energy of Li–O2 batteries. [ABSTRACT FROM AUTHOR]

Soft robotics has received substantial attention due to its remarkable deformability, making it well-suited for a wide range of applications in complex environments, such as medicine, rescue operations, and exploration. Within this domain, the interaction of actuation and sensing is of utmost importance for controlling the movements and functions of soft robots. Nonetheless, current research predominantly focuses on isolated actuation and sensing capabilities, often neglecting the critical integration of these 2 domains to achieve intelligent functionality. In this review, we present a comprehensive survey of fundamental actuation strategies and multimodal actuation while also delving into advancements in proprioceptive and haptic sensing and their fusion. We emphasize the importance of integrating actuation and sensing in soft robotics, presenting 3 integration methodologies, namely, sensor surface integration, sensor internal integration, and closed-loop system integration based on sensor feedback. Furthermore, we highlight the challenges in the field and suggest compelling directions for future research. Through this comprehensive synthesis, we aim to stimulate further curiosity among researchers and contribute to the development of genuinely intelligent soft robots., (Copyright © 2024 Shuai Zhou et al.)

For mass production of high-purity hydrogen fuel by electrochemical water splitting, seawater electrolysis is an attractive alternative to the traditional freshwater electrolysis due to the abundance and low cost of seawater in nature. However, the undesirable chlorine ion oxidation reactions occurring simultaneously with seawater electrolysis greatly hinder the overall performance of seawater electrolysis. To tackle this problem, electrocatalysts of high activity and selectivity with purposely modulated coordination and an alkaline environment are urgently required. Herein, it is demonstrated that atomically dispersed Ni with triple nitrogen coordination (Ni-N 3 ) can achieve efficient hydrogen evolution reaction (HER) performance in alkaline media. The atomically dispersed Ni electrocatalysts exhibit overpotentials as low as 102 and 139 mV at 10 mA cm -2 in alkaline freshwater and seawater electrolytes, respectively, which compare favorably with those previously reported. They also deliver large current densities beyond 200 mA cm -2 at lower overpotentials than Pt/C, as well as show negligible current attenuation over 14 h. The X-ray absorption fine structure (XAFS) experimental analysis and density functional theory (DFT) calculations verify that the Ni-N 3 coordination, which exhibits a lower coordination number than Ni-N 4 , facilitates water dissociation and hydrogen adsorption, and hence enhances the HER activity., (© 2020 Wiley-VCH GmbH.)

In Li-CO 2 battery, due to the highly insulating nature of the discharge product of Li 2 CO 3 , the battery needs to be charged at a high charge overpotential, leading to severe cathode and electrolyte instability and hence poor battery cycle performance. Developing efficient cathode catalysts to effectively reduce the charge overpotential represents one of key challenges to realize practical Li-CO 2 batteries. Here, we report the use of monodispersed Ru nanoparticles functionalized graphene nanosheets as cathode catalysts in Li-CO 2 battery to significantly lower the charge overpotential for the electrochemical decomposition of Li 2 CO 3 . In our battery, a low charge voltage of 4.02 V, a high Coulomb efficiency of 89.2%, and a good cycle stability (67 cycles at a 500 mA h/g limited capacity) are achieved. It is also found that O 2 plays an essential role in the discharge process of the rechargeable Li-CO 2 battery. Under the pure CO 2 environment, Li-CO 2 battery exhibits negligible discharge capacity; however, after introducing 2% O 2 (volume ratio) into CO 2 , the O 2 -assisted Li-CO 2 battery can deliver a high capacity of 4742 mA h/g. Through an in situ quantitative differential electrochemical mass spectrometry investigation, the final discharge product Li 2 CO 3 is proposed to form via the reaction 4Li + + 2CO 2 + O 2 + 4e - → 2Li 2 CO 3 . Our results validate the essential role of O 2 and can help deepen the understanding of the discharge and charge reaction mechanisms of the Li-CO 2 battery., Competing Interests: The authors declare no competing financial interest.

Correction for 'Recent advances in understanding of the mechanism and control of Li 2 O 2 formation in aprotic Li-O 2 batteries' by Zhiyang Lyu et al., Chem. Soc. Rev., 2017, DOI: 10.1039/c7cs00255f.

Aprotic Li-O 2 batteries represent promising alternative devices for electrical energy storage owing to their extremely high energy densities. Upon discharge, insulating solid Li 2 O 2 forms on cathode surfaces, which is usually governed by two growth models, namely the solution model and the surface model. These Li 2 O 2 growth models can largely determine the battery performances such as the discharge capacity, round-trip efficiency and cycling stability. Understanding the Li 2 O 2 formation mechanism and controlling its growth are essential to fully realize the technological potential of Li-O 2 batteries. In this review, we overview the recent advances in understanding the electrochemical and chemical processes that occur during the Li 2 O 2 formation. In the beginning, the oxygen reduction mechanisms, the identification of O 2 - /LiO 2 intermediates, and their influence on the Li 2 O 2 morphology have been discussed. The effects of the discharge current density and potential on the Li 2 O 2 growth model have been subsequently reviewed. Special focus is then given to the prominent strategies, including the electrolyte-mediated strategy and the cathode-catalyst-tailoring strategy, for controlling the Li 2 O 2 growth pathways. Finally, we conclude by discussing the profound implications of controlling Li 2 O 2 formation for further development in Li-O 2 batteries.

Black phosphorus (BP) shows great potential in electronic and optoelectronic devices owing to its semiconducting properties, such as thickness-dependent direct bandgap and ambipolar transport characteristics. However, the poor stability of BP in air seriously limits its practical applications. To develop effective schemes to protect BP, it is crucial to reveal the degradation mechanism under various environments. To date, it is generally accepted that BP degrades in air via light-induced oxidation. Herein, we report a new degradation channel via water-catalyzed oxidation of BP in the dark. When oxygen co-adsorbs with highly polarized water molecules on BP surface, the polarization effect of water can significantly lower the energy levels of oxygen (i.e. enhanced electron affinity), thereby facilitating the electron transfer from BP to oxygen to trigger the BP oxidation even in the dark environment. This new degradation mechanism lays important foundation for the development of proper protecting schemes in black phosphorus-based devices., (© 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

We report the synthesis of porous CoMoO 4 nanorods and their applications in lithium oxygen (Li-O 2 ) and lithium ion (Li-ion) batteries. The unique porous structures of CoMoO 4 nanorods can promote the permeation of electrolyte and benefit the transport of lithium ion. When employed as the cathode catalyst for a Li-O 2 battery, CoMoO 4 nanorods deliver an improved discharge capacity (4680 mA h g -1 ), lower charge potential and better cycle stability (41 cycles at 500 mA h g -1 capacity limit) compared with the bare carbon. When employed as an anode in Li-ion batteries, CoMoO 4 nanorods can retain a capacity of 603 mA h g -1 after 300 cycles (400 mA g -1 ) and exhibit excellent rate capability.

A rechargeable lithium-oxygen (Li-O2) battery with a remarkably high theoretical energy storage capacity has attracted enormous research attention. However, the poor oxygen reduction and oxygen evolution reaction (ORR and OER) activities in discharge and charge processes cause low energy efficiency, poor electrolyte stability and short cycle life. This requires the development of efficient cathode catalysts to dramatically improve the Li-O2 battery performances. MnO2-based materials are recognized as efficient and low-cost catalysts for a Li-O2 battery cathode. Here, we report a controllable approach to synthesize hierarchical porous δ-MnO2 nanoboxes by using Prussian blue analogues as the precursors. The obtained products possess hierarchical pore size and an extremely large surface area (249.3 m(2) g(-1)), which would favour oxygen transportation and provide more catalytically active sites to promote ORR and OER as the Li-O2 battery cathode. The battery shows enhanced discharge capacity (4368 mA h g(-1)@0.08 mA cm(-2)), reduced overpotential (270 mV), improved rate performance and excellent cycle stability (248 cycles@500 mA h g(-1) and 112 cycles@1000 mA h g(-1)), in comparison with the battery with a VX-72 carbon cathode. The superb performance of the hierarchical porous δ-MnO2 nanoboxes, together with a convenient fabrication method, presents an alternative to develop advanced cathode catalysts for the Li-O2 battery.