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Developing highly efficient, inexpensive catalysts for oxygen electrocatalysis in alkaline electrolytes (i.e., the oxygen reduction reaction (ORR) and the oxygen evolution reaction (OER)) is essential for constructing advanced energy conversion techniques (such as electrolyzers, fuel cells, and metal–air batteries). Recent achievements in efficient noble metal-free ORR and OER catalysts make the replacement of conventional noble metal counterparts a realistic possibility. In particular, various electronic structure regulation strategies have been employed to endow these oxygen catalysts with attractive physicochemical properties and strong synergistic effects, providing significant fundamental understanding to advance in this direction. This review article summarizes recently developed electronic structure regulation strategies for three types of noble metal-free oxygen catalysts: transition metal compounds, single-atom catalysts, and metal-free catalysts. We begin by briefly presenting the basic ORR and OER reaction mechanisms, following this with an analysis of the fundamental relationship between electronic structure and intrinsic electrocatalytic activity for the three categories of catalysts. Subsequently, recent advances in electronic structure regulation strategies for noble metal-free ORR and OER catalysts are systematically discussed. We conclude by summarizing the remaining challenges and presenting our outlook on the future for designing and synthesizing noble metal-free oxygen electrocatalysts.

The electrolyte-assisted exfoliation strategy is widely employed to synthesize ultrathin two-dimensional (2D) materials. Yet, spins in 2D magnets are susceptible to the electrolyte due to the underlying charge doping effect. Hence, it is crucial to understand and trace the doping process during the delamination of 2D magnets. Taking the prototype Fe₃GeTe₂, we utilized soft organic cations to exfoliate the bulk and obtain a freestanding organic–inorganic hybrid superlattice with a giant electron doping effect as high as 6.9 ​× ​10¹⁴/cm² (∼1.15 electrons per formula unit). A remarkable ferromagnetic transition exceeding 385 ​K was revealed in these superlattices, together with unique anisotropic saturation magnetization. The doping enhanced the in-plane electron–phonon coupling and thus optimized originally poor indirect double-exchange scenario for spin electrons. The emerging vertical magnetization shift phenomenon served to evaluate the uniformity of charge doping. The above findings provide a new perspective for understanding the role of parasitic charge in 2D magnetism.

Understanding and tuning charge transport over a single molecule is a fundamental topic in molecular electronics. Single-molecule junctions composed of individual molecules attached to two electrodes are the most common components built for single-molecule charge transport studies. During the past two decades, rapid technical and theoretical advances in single-molecule junctions have increased our understanding of the conductance properties and functions of molecular devices. In this perspective article, we introduce the basic principles of charge transport in single-molecule junctions, then give an overview of recent progress in modulating single-molecule transport through external stimuli such as electric field and potential, light, mechanical force, heat, and chemical environment. Lastly, we discuss challenges and offer views on future developments in molecular electronics.

A way of directly repairing spent lithium-ion battery cathode materials is needed in response to environmental pollution and resource depletion. In this work, we report a green repair method involving coupled mechanochemistry and solid-state reactions for spent lithium-ion batteries. During the ball-milling repair process, an added manganese source enters into the degraded LiMn₂O₄ (LMO) crystal structure in order to fill the Mn vacancies formed by Mn deficiency due to the Jahn–Teller effect, thereby repairing the LMO's chemical composition. An added carbon source acts not only as a lubricant but also as a conductor to improve the material's electrical conductivity. Meanwhile, mechanical force reduces the crystal size of the LMO particles, increasing the amount of active sites for electrochemical reactions. Jahn–Teller distortion is successfully suppressed by cation disorder in the LMO material. The cycling stability and rate performance of the repaired cathode material are thereby greatly improved, with the discharge specific capacity being more than twice that of commercial LMO. The proposed solid-state mechanochemical in situ repair process, which is safe for the environment and simple to use, may be extended to the repair of other waste materials without consuming highly acidic or alkaline chemical reagents.

With their intrinsic safety and environmental benignity, aqueous Zn-ion batteries (ZIBs) have been considered the most appropriate candidates for replacing alkali metal systems. However, polycrystalline Zn anodes in aqueous environments still pose enormous issues, such as dendrite growth and side reactions. Although many efforts have been made to address these obstacles through interphase modification and electrolyte design, researchers have not been able to improve the inherent thermodynamic stability and ion deposition behavior of the Zn anode. It is imperative to understand and explore advanced anode construction methods from the perspective of crystallinity. This review delves into the feasibility of precisely regulating the crystallographic features of metallic zinc, examines the challenges and merits of reported strategies for fabricating textured zinc, and offers constructive suggestions for the large-scale production and commercial application of aqueous ZIBs.

By effectively converting waste heat into electricity, thermoelectric materials and devices can provide an alternative approach to tackle the energy crisis. Amongst thermoelectric materials, bismuth telluride (Bi₂Te₃) and its derivatives exhibit high figure of merit ZT values in the near-room-temperature region and show great potential for application in thermoelectric devices. Considering the rapid development of Bi₂Te₃-based thermoelectric materials and their devices in the last few years, a short and systematic review is much needed. Here, we summarize the novel designs, properties, and applications of Bi₂Te₃-based thermoelectric devices in different contexts, including wearable, portable, implantable, and cross-disciplinary applications. The challenges and outlook for Bi₂Te₃-based thermoelectric devices are also considered. This work will guide the future development of Bi₂Te₃-based thermoelectric devices that target broader and more practical applications.

Li–CO₂ batteries, which integrate CO₂ utilization and electrochemical energy storage, offer the prospect of utilizing a greenhouse gas and providing an alternative to the well-established lithium-ion batteries. However, they still suffer from rather limited reversibility, low energy efficiency, and sluggish CO₂ redox reaction kinetics. To address these key issues, a nanoporous Ni₃Al intermetallic/Ni heterojunction (NP–Ni₃Al/Ni) is purposely engineered here via an alloying–etching protocol, whereby the unique interactions between Al and Ni in Ni₃Al endow NP-Ni₃Al/Ni with optimum reactant/product adsorption and thus unique catalytic performance for the CO₂ redox reaction. Furthermore, the nanoporous spongy structure benefits mass transport as well as discharge product storage and enables a rich multiphase reaction interface. In situ Raman studies and theoretical simulations reveal that both CO₂ reduction and the co-decomposition of Li₂CO₃ and C are distinctly promoted by NP-Ni₃Al/Ni, thereby greatly improving catalytic activity and stability. NP-Ni₃Al/Ni offers promising application potential in Li–CO₂ batteries, with its scalable fabrication, low production cost, and superior catalytic performance.

The performance of tin-based perovskite solar cells has been substantially hampered by voltage loss caused by energy level mismatch, charge recombination, energetic disorder, and other issues. Here, a fused-ring electron acceptor based on indacenodithiophene (IDIC) was for the first time introduced as a transition layer between a tin-based perovskite layer and a C₆₀ electron transport layer, leading to better matched energy levels in the device. In addition, coordination interactions between IDIC and perovskite improved the latter's crystallinity. The introduction of IDIC raised the power conversion efficiency from 8.98% to 11.5% and improved the device's stability. The decomposition mechanism of tin-based perovskite was also revealed by detecting the optical properties of perovskite microdomains through innovative integration of confocal laser scanning microscopy and photoluminescence spectroscopy.

Aqueous rechargeable Li/Na-ion batteries have shown promise for sustainable large-scale energy storage due to their safety, low cost, and environmental benignity. However, practical applications of aqueous batteries are plagued by water's intrinsically narrow electrochemical stability window, which results in low energy density. In this perspective article, we review several strategies to broaden the electrochemical window of aqueous electrolytes and realize high-energy aqueous batteries. Specifically, we highlight our recent findings on stabilizing aqueous Li storage electrochemistry using a deuterium dioxide-based aqueous electrolyte, which shows significant hydrogen isotope effects that trigger a wider electrochemical window and inhibit detrimental parasitic processes.

Microenvironments of the catalytic center, which play a vital role in adjusting electrocatalytic CO₂ reduction reaction (ECO₂RR) activity, have received increasing attention during the past few years. However, controllable microenvironment construction and the effects of multi-microenvironment variations for improving ECO₂RR performance remain unclear. Herein, we summarize the representative strategies for tuning the catalyst and local microenvironments to enhance ECO₂RR selectivity and activity. The multifactor synergetic effects of microenvironment regulation for enhancing CO₂ accessibility, stabilizing key intermediates, and improving the performance of ECO₂RR catalysts are discussed in detail, as well as perspectives on the challenges when investigating ECO₂RR microenvironments. We anticipate that the discussions in this review will inspire further research in microenvironment engineering to accelerate the development of the ECO₂RR for practical application.