Two-dimensional (2D) materials display a unique set of physical/chemical properties and are considered potential building blocks for the manufacturing of microstructured materials for a number of applications. Prominent applications range from advanced electronics to miniaturized electrochemical energy storage devices (EESDs). Herein, we present a comprehensive and critical review of the recent developments in design and microfabrication of 2D-driven microscale electrodes for three-dimensional (3D)-printed micro-supercapacitors and micro-batteries. Firstly, we systematically discuss the advantages and disadvantages associated with various microfabrication techniques such as stereolithography, fused deposition modeling, inkjet printing, and direct ink writing. Next, key parameters disclosing the relationship between the characteristics of 2D-based materials and extrusion-driven 3D printing process for the development of versatile and sustainable EESDs are highlighted. 2D materials utilized for the construction of microelectrodes for supercapacitors (e.g., electric double layer capacitors (EDLCs), pseudocapacitors, and hybrid capacitors) and batteries (e.g., Li-based systems and next-generation systems, e.g., sodium-ion batteries and zinc-ion batteries) along with their prominent electrochemical contributions in relation to obtained 3D-printed architectures are discussed in detail. To promote the development of 2D materials-driven high-performance microscale EESDs, the relevant challenges and future research opportunities are also addressed.

In recent years, non-aqueous fully organic Redox Flow Batteries (RFBs) have displayed potential in broadening the electrochemical window and enhancing energy density in RFBs by relying on redox-active organic molecules to provide improved sustainability in comparison to metal-based charge carriers. Of particular interest, systems that rely on a single bipolar redox molecule (BRM) for their operation, known as symmetrical organic RFBs, have gained momentum as the utilization of a BRM eliminates membrane crossover issues, thus extending the lifespan of electrical energy storage systems while reducing their cost. In this manuscript, we will present our contribution to this field through the design of tunable bipolar molecules within the helicene carbocation class. This particular type of BRM is synthetically very affordable and has proven to be highly modifiable and robust. Through the examination of 11 examples, we will demonstrate how an approach based on readily available electrochemical tools can be efficiently employed to generate and assess a library of compounds for future full flow RFB applications.

The inevitable shuttling of lithium polysulfides (LiPSs) and poor redox kinetics restrict real-world applications of lithium-sulfur (Li-S) batteries, although they have been paid plentiful attention. Herein, a thin and multifunctional heterostructure (ZIF-L/MXene), consisting of leaf-like zeolitic imidazolate framework sheets (ZIF-L) and two-dimensional layered Ti₃C₂T_x MXene nanosheets, is developed for modification of polyolefin-based separators. A good combination of the merits of the ZIF-L and MXene can hinder the restacking of MXene nanosheets and achieve a large specific surface area, thus exposing plentiful active sites for adsorption and catalytic reaction of LiPSs. Taking these obviously synergistic effects, the ZIF-L/MXene heterostructure modified separators not only alleviate the shuttling of LiPSs but also promote their kinetics conversion. Furthermore, with an improved electrolyte affinity, the ZIF-L/MXene modified separators can accelerate the transport of Li⁺. Thus, the modified separator endows a Li-S cell with an admirable discharge capacity of 1371.7 mAh g^-1 at 0.2 C and favorable cycling stability, with a slow capacity decay ratio of 0.075% per cycle during 500 cycles. Even under a sulfur loading of ~ 4.1 mg cm^-2, the Li-S battery can achieve an excellent capacity of 990.6 mAh g^-1 at 0.1 C and maintain an excellent cycling performance. The novel ZIF-L/MXene heterostructure modified separator in this work can provide an alternative strategy for designing thin and light separators for high-performance Li-S batteries, via the enhancement of redox kinetics and reduction of shuttling of the LiPSs.

Due to the excellent stability of titanium dioxide (TiO₂), there is still value in improving its solar-to-hydrogen conversion efficiency through tremendous attempts. Metal sulfides with a narrow bandgap are good candidates to broaden the ultraviolet light absorption of TiO₂ into the visible light region. However, sulfides suffer from the photocorrosion issue, leading to poor stability. Herein, a type-II heterojunction of TiO₂/In₂S₃ is fabricated by a hydrothermal method, and a NiFe Prussian blue analog (NFP) overlayer is deposited on the surface of TiO₂/In₂S₃ through a chemical bath deposition technique. Under AM1.5G illumination, a photocurrent density of 1.81 mA cm^-2 can be obtained with NFP coated TiO₂/In₂S₃ at 1.23 V vs. reversible hydrogen electrode, which is six folds of the photocurrent of TiO₂. This photocurrent value can reach up to about 90% of its theoretical photocurrent. During a 12 h stability test, the TiO₂/In₂S₃/NFP photoanode exhibits a high photocurrent retention of 95.17% after an initial transient decrease. The type-II heterojunction of TiO₂/In₂S₃ can efficiently boost the charge separation because of the built-in electric field and enhance the visible-light absorption because of the narrow bandgap of In₂S₃. A NFP overlayer serves as the cocatalyst for water oxidation reaction due to its valence changes of nickel and iron elements. NFP cocatalyst can rapidly extract the photogenerated holes from In₂S₃ and then improve the charge separation/injection efficiencies. Thanks to chemical stability of NFP, its coating can also make In₂S₃ resistant to photocorrosion by physically separating the photoanode from the electrolyte. Therefore, there is a good synergistic effect between the TiO₂/In₂S₃ heterojunction and NFP cocatalyst. This work provides some crucial insights for the interface engineering and material design in photoelectrochemical systems.

Lithium (Li⁰) metal has been deemed the desired anode for the future of cutting-edge rechargeable Li batteries benefiting from its lowest reduction potential and ultrahigh theoretical specific capacity. Nevertheless, the large-scale applications of Li metal batteries are restricted by scattered Li dendrite formation and uncontrollable volume expansion. To address these issues, a currently prevalent measure is to use structured lithiophilic hosts for Li metal. The enhanced lithiophilicity of hosts is significant for regulating the Li nucleation barrier. By virtue of these lithiophilic measures, the Li nucleation sites will be well controlled and the Li plating layer will be more stable. Through this article, we classified various lithiophilic hosts and described their applications for Li metal batteries, including heteroatom-doping carbon, lithiophilic-material loading hosts and gradient skeletons. We discussed the inherent advantages and lithophilic mechanisms of these hosts on optimizing the lithophilic properties and analyzed various factors that induced the formation of dendrite Li. Moreover, the review outlines the current challenges and perspectives for Li metal anodes, and some understanding of the lithiophilic chemistry is given.

Integrating metallic lithium (Li) with a three-dimensional (3D) host is a popular strategy for long-life Li composite anodes, where the structure and physicochemical nature of the framework are critical for the electrochemical performance. Herein, Li-rich dual-phase barium (Ba)-based alloy composed of BaLi₄ intermetallic compounds and Li metal phases is thermally incorporated into commercial carbon cloth sheets to develop Li-Ba alloy composite (LBAC) anodes featuring a porous array of BaLi₄ microchannels as the built-in 3D skeleton. Doping of metallic Ba can greatly lower the surface tension of liquid Li and improve the wettability of the molten Li-Ba alloy toward the carbon cloth substrate. Moreover, LBAC benefits from the superior lithiophilicity and the porous architecture of BaLi₄ skeleton nested in a conductive carbon fiber matrix, leading to stable cycling performance by confining Li stripping/plating in microchannels network of BaLi₄ alloy framework and dissipating high current densities. As a result, the LBAC symmetrical cells can run stably for 1,000 h under 1 mA cm^-2 and 1 mA h cm^-2, and the capacity retention can retain 93.3% after 300 cycles in the full cell with areal capacity of 2.45 mA h cm^-2. This work offers a smart designing strategy of 3D Li alloy composite anodes by introducing porous and lithiophilic alloy scaffold as sub-framework of the carbon hosting anode, promising the prospect of Li metal batteries for future applications.

Single-atomic-site catalysts have been demonstrated as promising candidates for electrochemical CO₂ reduction reaction (eCO₂RR). However, the universal construction strategies need to be further developed to synthesize the desired single-atomic-site catalysts with high eCO₂RR activity for feasible CO₂ utilization. Herein, a novel 2-methylimidazole-phthalocyanine-Ni (IM₄NiPc) coordinatively modified ZIF-8 was rationally fabricated and applied to derive the single-atomic-Ni electrocatalyst (Ni-N-C-l), which is capable of delivering much improved activity for eCO₂RR, compared to the pristine IM₄NiPc immobilized onto ZIF-8-derived N-doped carbon surface, and is also comparable to the best reported catalysts. The satisfied Faradaic efficiency, current density and stability of CO₂-to-CO electroconversion over Ni-N-C-l are shown to originate from the verified Ni-N₄ configuration, particularly, reaching a CO Faradaic efficiency of 99% in a wide potential range. Moreover, based on the outstanding eCO₂RR activity of Ni-N-C-l, we successfully realized the exemplary synthesis of amide polymer materials through CO-mediated electro/thermocatalytic cascade processes, demonstrating the feasibility of utilizing CO₂ for material manufacturing. This finding is expected to provide useful insight on the precise design and rational synthesis of the novel single-atomic-site catalysts for future CO₂ intelligent utilization.

Aqueous zinc batteries that utilize metallic Zn as the anode are considered as a promising alternative to lithium-ion batteries due to their intrinsic high safety, low cost, and relatively high energy density. Compared to inorganic cathodes, organic cathodes exhibit several advantages including high theoretical capacity, tunable structure, abundant sources, and environmental friendliness. In this paper, we summarize the recent progress in organic cathodes for aqueous zinc-organic batteries, covering the working mechanisms of three typical types of organic cathodes, their electrochemical performance, and common strategies for further improvement. Finally, we discuss the current challenges and possible future research directions. We hope this review will offer useful information for exploring high-performance organic cathodes.

Organic-inorganic hybrid perovskites have emerged as an up-and-coming contender for photovoltaic devices owing to their exceptional photovoltaic properties. However, current research predominantly concentrates on their performance under ambient conditions at room temperature. In this work, we delve into the novel territory by investigating MAPbI₃-based and FAPbI₃-based perovskite solar cells (PSCs) in the temperature range of 300 to 150 K. Remarkable efficiency enhancements of nearly 5% and 20% were obtained at 250 and 210 K, respectively. However, further decreasing the temperature impairs the photovoltaic performance. We propose an underlying mechanism influencing the performance change in perovskite devices at low temperatures by examining the temperature-dependent ultraviolet-visible and photoluminescence spectra results. At the beginning of the cooling process, from 300 to 250 K for MAPbI₃ and from 300 to 210 K for FAPbI₃, the performance enhancement stems primarily from the enhanced open-circuit voltage by the tuned band gap of the perovskite films. Further lowering the temperature would change the perovskite structure, impairing the performance of PSCs. FAPbI₃-based PSCs show a better tolerance in low temperatures owing to the more stable perovskite crystal structure. The present findings offer valuable theoretical guidance for preparing outstanding PSCs for low-temperature applications.

In the field of advanced materials and energy harvesting, MXene has played a pivotal role in advancing the development of triboelectric nanogenerators (TENGs). This contribution is notable not only in terms of enhancing the performance of TENGs but also in expanding their application range. A comprehensive review of MXene materials is offered herein to delve into the significant impact of MXene on the growing efficiency of energy harvesting and widening application in areas ranging from energy harvesters to physiochemical sensors to self-powered intelligent systems. We begin with the fundamentals of MXene and TENGs, then highlight how MXene improves TENGs via its integration into the triboelectrification and electrode layers to increase the electronegativity, charge density, and introduce self-healing and stretchability. The discussion then extends to the modifications in MXene that boost the electrical output, stability, and collection efficiency of TENGs. Additionally, the review covers the diverse applications of MXene-based TENGs in extreme environments, respiratory monitoring, and multi-purpose devices, emphasizing its critical role in promoting TENGs to future self-powered intelligent systems.

Perovskite solar cells have demonstrated remarkable progress in recent years. However, their widespread commercialization faces challenges arising from defects and environmental vulnerabilities, leading to limitations in energy conversion efficiency and device stability. To overcome these hurdles, passivation technologies have emerged as a promising avenue. These passivators are strategically applied at the interface between perovskite absorbers and charge transport layers to mitigate the adverse effects of defects and environmental factors. While prior reviews have predominantly focused on experimental observations, a comprehensive theoretical understanding of the passivators has been lacking. This review focuses on recent advancements in first-principles density functional theory studies that delve into the fundamental properties of passivators and their intricate interactions with perovskite materials and charge transport layers. By exploring the atomic-level roles of passivators, this review elucidates their impact on critical parameters such as open circuit voltage (V_oc), short circuit current density (J_sc), fill factor, and the overall stability of perovskite solar cells. The synthesis of theoretical insights from these studies can serve as guidelines for the molecular design of passivators with the ultimate objective of advancing the commercialization of high-performance perovskite solar cells.

Sodium-ion batteries (SIBs) are regarded as an outstanding alternative to lithium-ion batteries (LIBs) due to abundant sodium sources and their similar chemistry. As a most promising anode of SIBs, hard carbons (HCs) receive extensive attention because of their low potential and low cost, but their rational design for commercial SIBs is restricted by their variable and complicated microstructure, which is analogous to that of graphite in LIBs. Herein, a series of controllable HC materials derived from 3-aminophenol formaldehyde resin (AFR) were designed and fabricated. We discover that the optimized HC features expanded graphite regions, highly developed nanopores, and reduced defect content, contributing to the enhanced Na⁺ storage. This optimization is achieved by adjusting the resin crosslinking degree of the precursor. Specifically, a resin precursor with a higher crosslinking degree can produce HC with a larger interlayer distance, relatively higher crystallinity, and a lower specific surface area. Encouragingly, the as-optimized AFR-HC electrode manifests superior electrochemical performance in the aspect of high capacity (383 mAh·g^-1 at 0.05 A·g^-1), better rate capability (140 mAh·g^-1 at 20 A·g^-1), and high initial coulombic efficiency (82%) than other contrast samples. Moreover, the as-constructed full cell coupled with a Na₃V₂(PO₄)₃ cathode shows an energy density of 250 Wh·kg^-1. Together with the simple synthesis, cost-efficiency of the precursors and superior electrochemical performance, AFR-HCs are promising for the commercial application.

Metal batteries using lithium, sodium, potassium, zinc, etc., as anodes have garnered tremendous attention in rechargeable batteries because of their highly desirable theoretical energy densities. However, large-scale application of these metal batteries is impeded by dendrite growth on the anode surface, which may penetrate the separator, leading to battery failure. Two dimensional (2D) materials featured by excellent mechanical strength and flexibility, tunable electronic properties and controllable assembly are promising materials for the construction of dendrite-free metal batteries. In this review, we summarize recent advancements of 2D materials for their potential use in critical components of dendrite-free batteries used as: (1) a host or artificial solid-electrolyte for metal anodes; (2) a solid electrolyte or modifier for electrolyte; and (3) an enhancement component for separators design. We conclude that 2D materials hold great promise for tackling the problems associated with dendrite formation by functioning as mechanical reinforcement and metal deposition regulators, along with improved safety, performance, and durability of batteries. Finally, this review discusses new perspectives and future directions in the field of 2D materials towards safe, high-energy metal batteries.