A Single-cell transcriptome atlas reveals the trajectory of early cell fate transition during callus induction in Arabidopsis.

The acquisition of pluripotent callus from somatic cells plays an important role in plant development studies and the genetic improvement of crops. This developmental process incorporates a series of cell fate transitions and reprogramming. However, our knowledge of cell heterogeneity and of the mechanisms of cell fate transition during callus induction remains quite limited. Here, we performed a time series single-cell transcriptome experiment on Arabidopsis root explants that were induced in callus induction medium for 0 days, 1 day, and 4 days, and we constructed a detailed single-cell transcriptional atlas of the callus induction process. We identified the cell types responsible for initiating the early callus: lateral root primordia-initiating (LRPI)-like cells and quiescent center (QC)-like cells. LRPI-like cells are derived from xylem pole pericycle cells and are similar to lateral root primordia. We delineate the developmental trajectory of the dedifferentiation of LRPI-like cells into QC-like cells. QC-like cells are undifferentiated pluripotent acquired cells that appear in the early stages of callus formation and play a critical role in later callus development and organ regeneration. We further inferred the transcription factors that regulating QC-like cells and the gene expression signatures that are related to cell fate decisions. Overall, our cell-lineage transcriptome atlas for callus induction provides a distinct perspective on cell fate transition during callus formation, and significantly improves understanding of callus formation.

Hierarchical porous carbon materials for lithium storage: Preparation, modification, and applications.

Secondary battery as an efficient energy conversion device have been highly attractive for alleviating the energy crisis and environmental pollution. Hierarchical porous carbon materials with multiple sizes pore channels are considered as promising materials for energy conversion and storage applications, due to their high specific surface area and excellent electrical conductivity. Although many reviews have reported on carbon materials for different fields, systematic summaries about hierarchical porous carbon materials for lithium storage are still rare. In this review, we fist summarize the main preparation methods of hierarchical porous carbon materials, including hard template method, soft template method, and template-free method. The modification methods including porosity and morphology tuning, heteroatom doping, and multiphase composites are introduced systematically. Then, the recent advances in hierarchical porous carbon materials on lithium storage are summarized. Finally, we outline the challenges and future perspectives for the application of hierarchical porous carbon materials in lithium storage.

A p-block dopant enables energy-efficient hydrogen production from biomass.

Herein, we develop innovative p-block Bi-doped Co3O4 nanoflakes (Bi-Co3O4 NFAs) on nickel foam, which exhibit excellent electrocatalytic activity for both glucose oxidation (GOR) and H2 evolution reactions (HER). The two-electrode GOR-HER electrolyzer using Bi-Co3O4 NFAs as both the cathode and anode shows a remarkable reduced operation voltage of 1.48 V at 10 mA cm-2, superior to the 1.66 V of the OER-HER electrolyzer, demonstrating promising potential for advanced H2 production featuring energy saving and simultaneously produced value-added chemicals.

Electrocatalytic nitrate-to-ammonia conversion on CoO/CuO nanoarrays using Zn-nitrate batteries.

Zn-NO3- batteries can generate electricity while producing NH3 in an environmentally friendly manner, making them a very promising device. However, the conversion of NO3- to NH3 involves a proton-assisted 8-electron (8e-) transfer process with a high kinetic barrier, requiring high-performance catalysts to realize the potential applications of this technology. Herein, we propose a heterostructured CoO/CuO nanoarray electrocatalyst prepared on a copper foam (CoO/CuO-NA/CF) that can electrocatalytically and efficiently convert NO3- to NH3 at low potential and achieves a maximum NH3 yield of 296.9 µmol h-1 cm-2 and the Faraday efficiency (FE) of 92.9% at the -0.2 V vs. reversible hydrogen electrode (RHE). Impressively, Zn-NO3- battery based on the monolithic CoO/CuO-NA/CF electrode delivers a high NH3 yield of 60.3 µmol h-1 cm-2, FENH3 of 82.0%, and a power density of 4.3 mW cm-2. This study provides a paradigm for heterostructured catalyst preparation for the energy-efficient production of NH3 and simultaneously generating electrical energy.

Phase Engineering of Molybdenum Carbide-Cobalt Heterostructures for Long-Lasting Zn-Air Batteries.

Developing highly active and robust oxygen catalysts is of great significance for the commercialization of Zn-air batteries (ZABs) with long-life stability. Herein, heterostructured catalysts comprising molybdenum carbide and metallic Co are prepared by a simple dicyandiamide-assisted pyrolysis strategy. Importantly, the crystalline phase of molybdenum carbide in the catalysts can be carefully regulated by adjusting the CoMo-imidazole precursor and dicyandiamide ratio. The electronic configuration of Co and Mo centers as well as the phase-dependent oxygen reduction reaction performance of these heterostructures (ß-Mo2C/Co, ß-Mo2C/η-MoC/Co, and η-MoC/Co) was disclosed. A highly active η-MoC/Co cathode enables ZABs with outstanding long-term stability over 850 h with a low voltage decaying rate of 0.06 mV·h-1 and high peak power density of 162 mW·cm-2. This work provides a new idea for the rational design of efficient and stable cathode catalysts for ZABs.

Tunable Heterogeneous FeCo Alloy-Mo0.82N Bifunctional Electrocatalysts for Temperature-Adapted Zn-Air Batteries.

The practical applications of temperature-tolerant Zn-air batteries (ZABs) rely on highly active and stable bifunctional catalysts that accelerate cathodic oxygen reduction (ORR) and oxygen evolution (OER) reactions. Herein, we successfully integrated fascinating transition metal nitrides and FeCo alloys through a simple coordination assembly and pyrolysis process. Importantly, the alloy-to-nitride ratio in the heterogeneous catalyst can be carefully regulated through the subsequent etching process. Moreover, the composition-dependent ORR/OER performance of the FeCo-Mo0.82N catalysts was revealed. Aqueous ZABs using the optimized FeCo-Mo0.82N-60 as a cathode exhibit a high peak power density of 149.7 mW cm-2 and an impressive stability of 600 h with a low charge-discharge voltage gap decay rate of 0.025 mV h-1, which exceeds those of most of recent reports. Furthermore, the FeCo-Mo0.82N-60-based flexible ZABs display a small specific capacity degradation (3%) from 40 to -10 °C, demonstrating excellent temperature tolerance.

Achieving Ultralong-Cycle Zinc-Ion Battery via Synergistically Electronic and Structural Regulation of a MnO2 Nanocrystal-Carbon Hybrid Framework.

Aqueous rechargeable zinc-ion batteries (ZIBs) have attracted burgeoning interests owing to the prospect in large-scale and safe energy storage application. Although manganese oxides are one of the typical cathodes of ZIBs, their practical usage is still hindered by poor service life and rate performance. Here, a MnO2 -carbon hybrid framework is reported, which is obtained in a reaction between the dimethylimidazole ligand from a rational designed MOF array and potassium permanganate, achieving ultralong-cycle-life ZIBs. The unique structural feature of uniform MnO2 nanocrystals which are well-distributed in the carbon matrix leads to a 90.4% capacity retention after 50 000 cycles. In situ characterization and theoretical calculations verify the co-ions intercalation with boosted reaction kinetics. The hybridization between MnO2 and carbon endows the hybrid with enhanced electrons/ions transport kinetics and robust structural stability. This work provides a facile strategy to enhance the battery performance of manganese oxide-based ZIBs.

Efficient interlayer confined nitrate reduction reaction and oxygen generation enabled by interlayer expansion.

Electrochemically converting nitrate ions back to ammonia can not only eliminate water pollution but also obtain valuable ammonia without a serious carbon footprint, and is thus deemed as an efficient supplement to the traditional Haber-Bosch process. Currently reported catalysts can achieve a single electrode reaction in the electrochemical nitrate reduction reaction. However, the bifunctionality of a single catalyst for both cathodic and anodic reactions has not yet been reported. Herein, we report Fe-doped layered α-Ni(OH)2 with expanded interlayer spacing as an efficient bifunctional catalyst for the nitrate reduction reaction and oxygen evolution reaction. The expanded interlayer spacing facilitates in situ electrochemical potassium ion intercalation between layers. In situ Raman spectroscopy characterization confirms that both the nitrate reduction reaction and oxygen evolution reaction are confined between layers and are triggered by the accumulation of potassium ions. The obtained α-Ni0.881Fe0.119(OH)2 nanosheets deliver an ammonia yield rate of 8.1 mol gcat.-1 h-1 with a NO3--to-NH3 faradaic efficiency of 97.5% at the cathode. The overpotential of oxygen generation at 10 mA cm-2 is reduced to 254 mV at the anode. As a bifunctional catalyst in overall electrolysis, the current density of α-Ni0.881Fe0.119(OH)2 reaches 24.8 mA cm-2 at a voltage of 2.0 V and performs continuously for 50 h with a current retention of 80.2%.

Chemical Transformation Induced Core-Shell Ni2P@Fe2P Heterostructures toward Efficient Electrocatalytic Oxygen Evolution.

The oxygen evolution reaction (OER) is a crucial reaction in water splitting, metal-air batteries, and other electrochemical conversion technologies. Rationally designed catalysts with rich active sites and high intrinsic activity have been considered as a hopeful strategy to address the sluggish kinetics for OER. However, constructing such active sites in non-noble catalysts still faces grand challenges. To this end, we fabricate a Ni2P@Fe2P core-shell structure with outperforming performance toward OER via chemical transformation of rationally designed Ni-MOF hybrid nanosheets. Specifically, the Ni-MOF nanosheets and their supported Fe-based nanomaterials were in situ transformed into porous Ni2P@Fe2P core-shell nanosheets composed of Ni2P and Fe2P nanodomains in homogenous dispersion via a phosphorization process. When employed as the OER electrocatalyst, the Ni2P@Fe2P core-shell nanosheets exhibits excellent OER performance, with a low overpotential of 238/247 mV to drive 50/100 mA cm-2, a small Tafel slope of 32.91 mV dec-1, as well as outstanding durability, which could be mainly ascribed to the strong electronic interaction between Ni2P and Fe2P nanodomains stabilizing more Ni and Fe atoms with higher valence. These high-valence metal sites promote the generation of high-active Ni/FeOOH to enhance OER activity.

Achieving Highly Reversible Zinc Anodes via N, N-Dimethylacetamide Enabled Zn-Ion Solvation Regulation.

Although aqueous zinc-ion batteries (ZIBs) are promising for scalable energy storage application, the actual performance of ZIBs is hampered by the irreversibility. Optimization of electrolyte composition is a relatively practical and facile way to improve coulombic efficiency (CE) and Zn plating/stripping reversibility of ZIBs. N,N-Dimethylacetamide (DMA) has a higher Gutmann donor number (DN) than that of H2 O, abundant polar groups, and economic price. Herein, a mixture electrolyte containing 10 vol% DMA and ZnSO4 , which has an enhanced Zn reversibility almost fourfold higher than that of pure ZnSO4 electrolyte, is demonstrated. The density functional theory (DFT) calculation and spectroscopic analysis reveal DMA has the ability to reconstruct the solvation structure of Zn2+ and capture free water molecules via forming Hbonds. The inhibited dendrite growth on Zn anode is further clarified by an in situ characterization. This work provides a feasible way for the development of long-lifespan ZIBs.

The single-cell stereo-seq reveals region-specific cell subtypes and transcriptome profiling in Arabidopsis leaves.

Understanding the complex functions of plant leaves requires a thorough characterization of discrete cell features. Although single-cell gene expression profiling technologies have been developed, their application in characterizing cell subtypes has not been achieved yet. Here, we present scStereo-seq (single-cell spatial enhanced resolution omics sequencing) that enabled us to show the bona fide single-cell spatial transcriptome profiles of Arabidopsis leaves. Subtle but significant transcriptomic differences between upper and lower epidermal cells have been successfully distinguished. Furthermore, we discovered cell-type-specific gene expression gradients from the main vein to the leaf edge, which led to the finding of distinct spatial developmental trajectories of vascular cells and guard cells. Our study showcases the importance of physical locations of individual cells for exerting complex biological functions in plants and demonstrates that scStereo-seq is a powerful tool to integrate single-cell location and transcriptome information for plant biology study.

Unlocking active metal site of Ti-MOF for boosted heterogeneous catalysis via a facile coordinative reconstruction.

Constructing sophisticated hollow structure and exposing more metal sites in metal-organic frameworks (MOFs) can not only enhance their catalytic performance but also endow them with new functions. Herein, we present a facile coordinative reconstruction strategy to transform Ti-MOF polyhedron into nanosheet-assembled hollow structure with a large amount of exposed metal sites. Importantly, the reconstruction process relies on the esterification reaction between the organic solvent, i.e. ethanol and the carboxylic acid ligand, allowing the conversion of MOF without the addition of any other modulators and/or surfactants. Moreover, the surface and internal structure of the reconstructed MOF can be well tuned via altering the conversion time. Impressively, the reconstructed MOF exhibits ∼5.1-fold rate constant compared to the pristine one in an important desulfurization reaction for clean fuels production, i.e. the oxidation of dibenzothiophene.

Bioinspired interfacial engineering of a CoSe2 decorated carbon framework cathode towards temperature-tolerant and flexible Zn-air batteries.

A high-performance air electrode is essential for the successful application of flexible Zn-air batteries in wearable devices. However, endowing the electrode-electrolyte interface with high stability and fast electron/ion transportation is still a great challenge. Herein, we report a bioinspired interfacial engineering strategy to construct a cactus-like hybrid electrode comprising CoSe2 nanoparticles embedded in an N-doped carbon nanosheet arrays penetrated with carbon nanotubes (CoSe2-NCNT NSA). Associated with the synergistic effect of highly active CoSe2 nanoparticles and N-doped carbon moieties and a stable 3D interconnected CNT network, the obtained self-standing electrode exhibits satisfactory catalytic activities towards oxygen evolution/reduction and hydrogen evolution, as well as an enhanced electrode-electrolyte interaction/interface area, and thus delivers superior performance for flexible Zn-air batteries. Remarkably, the fabricated flexible Zn-air battery with this CoSe2-NCNT NSA cathode achieves a high peak power density (51.1 mW cm-2), considerable mechanical flexibility, and excellent durability in a wide temperature range of 0 to 40 °C. Furthermore, the assembled Zn-air batteries can efficiently power a water-splitting device that adopts the CoSe2-NCNT NSA as both the anode and cathode, demonstrating promising potential in energy conversion and portable electronic applications.

Non-3d Metal Modulation of a 2D Ni-Co Heterostructure Array as Multifunctional Electrocatalyst for Portable Overall Water Splitting.

Portable water splitting devices driven by rechargeable metal-air batteries or solar cells are promising, however, their scalable usages are still hindered by lack of suitable multifunctional electrocatalysts. Here, a highly efficient multifunctional electrocatalyst is demonstrated, i.e., 2D nanosheet array of Mo-doped NiCo2 O4 /Co5.47 N heterostructure deposited on nickel foam (Mo-NiCo2 O4 /Co5.47 N/NF). The successful doping of non-3d high-valence metal into a heterostructured nanosheet array, which is directly grown on a conductive substrate endows the resultant catalyst with balanced electronic structure, highly exposed active sites, and binder-free electrode architecture. As a result, the Mo-NiCo2 O4 /Co5.47 N/NF exhibits remarkable catalytic activity toward the oxygen evolution reaction (OER) and hydrogen evolution reaction (HER), affording high current densities of 50 mA cm-2 at low overpotentials of 310 mV for OER, and 170 mV for HER, respectively. Moreover, a low voltage of 1.56 V is achieved for the Mo-NiCo2 O4 /Co5.47 N/NF-based water splitting cell to reach 10 mA cm-2 . More importantly, a portable overall water splitting device is demonstrated through the integration of a water-splitting cell and two Zn-air batteries (open-circuit voltage of 1.43 V), which are all fabricated based on Mo-NiCo2 O4 /Co5.47 N/NF, demonstrating a low-cost way to generate fuel energy. This work offers an effective strategy to develop high-performance metal-doped heterostructured electrode.

MnO2 Nanosheet-Assembled Hollow Polyhedron Grown on Carbon Cloth for Flexible Aqueous Zinc-Ion Batteries.

Aqueous zinc-ion batteries (ZIBs) have been considered as prospective alternatives for lithium-ion batteries, which are able to serve as power sources for next-generation wearable and flexible devices, owing to the merits of abundant zinc resources and high safety of aqueous electrolyte. However, the lack of suitable cathode materials with flexibility for ZIBs hinders their further application. Herein, a novel cathode material [i.e., MnO2 nanosheet-assembled hollow polyhedron anchored on carbon cloth (MnO2 /CC)] was prepared through a rapid hydrothermal method by using ZIF-67 as self-sacrificing template. When tested in an aqueous ZIB, the MnO2 /CC delivered a high reversible capacity of 263.9 mAh g-1 at 1.0 A g-1 after 300 cycles, far exceeding those of the commercial MnO2 electrode. More importantly, benefiting from the unique structural advantages, a flexible ZIB assembled based on the MnO2 /CC displayed a stable output voltage of 1.53 V and a specific capacity of 91.7 mAh g-1 at 0.1 A g-1 after 30 cycles. It also successfully lit LED bulbs even under different bending angles, showing good flexibility. This research contributes to the development of MnO2 -based cathode materials for high-performance flexible ZIBs.

Structural Engineering of Low-Dimensional Metal-Organic Frameworks: Synthesis, Properties, and Applications.

Low-dimensional metal-organic frameworks (LD MOFs) have attracted increasing attention in recent years, which successfully combine the unique properties of MOFs, e.g., large surface area, tailorable structure, and uniform cavity, with the distinctive physical and chemical properties of LD nanomaterials, e.g., high aspect ratio, abundant accessible active sites, and flexibility. Significant progress has been made in the morphological and structural regulation of LD MOFs in recent years. It is still of great significance to further explore the synthetic principles and dimensional-dependent properties of LD MOFs. In this review, recent progress in the synthesis of LD MOF-based materials and their applications are summarized, with an emphasis on the distinctive advantages of LD MOFs over their bulk counterparties. First, the unique physical and chemical properties of LD MOF-based materials are briefly introduced. Synthetic strategies of various LD MOFs, including 1D MOFs, 2D MOFs, and LD MOF-based composites, as well as their derivatives, are then summarized. Furthermore, the potential applications of LD MOF-based materials in catalysis, energy storage, gas adsorption and separation, and sensing are introduced. Finally, challenges and opportunities of this fascinating research field are proposed.

Bimetallic Metal-Organic Framework-Derived Carbon Nanotube-Based Frameworks for Enhanced Capacitive Deionization and Zn-Air Battery.

Carbon-based materials have attracted intensive attentions for a wide range of energy and environment-related applications. Energy storage/conversion devices with improved performance have been achieved by utilization of metal-organic-framework (MOF)-derived carbon structures as active materials in recent years. However, the effects of MOF precursors on the performance of derived carbon materials are rarely investigated. Here, we report that the incorporation of small amount of Fe or Ni in Co-based MOFs leads to a significant enhancement for the derived carbon nanotube-based frameworks (CNTFs) in Na+/Cl- ion electrosorption. Further investigation revealed the enhanced performance can be attributed to the improved specific surface area, electrical conductivity, and electrochemical activity. Notably, the CoFe-CNTF derived from bimetallic CoFe-MOFs achieves a high ion adsorption capacity of 37.0 mg g-1, superior to most of recently reported carbon-based materials. Furthermore, the CoFe-CNTF also demonstrates high catalytic activity toward oxygen evolution reaction (OER) with a Tafel slope of 87.7 mV dec-1. After combination with three-dimensional graphene foam (3DG), the resultant CoFe-CNTF-coated 3DG is used as air-cathode to fabricate a flexible all-solid-state Zn-air battery, which exhibits a high open circuit potential of 1.455 V. Importantly, the fabricated flexible battery can light a light-emitting diode (LED) even when it is bent. This work provides new insights into designs of high-performance and flexible electrode based on MOF-derived materials.

Fabrication of high-performance MXene-based all-solid-state flexible microsupercapacitor based on a facile scratch method.

MXenes have emerged as promising electrode materials for microsupercapacitors (MSCs) owing to their high volumetric and areal capacitances. In addition to the development of novel electrode materials, fabrication of interdigital electrodes is another key to realize high-performance MSCs. Herein, we demonstrate the patterning of few-layered Ti3C2T x nanosheets on various substrates for MSCs by a facile, fast, and nearly zero-cost 'scratch' strategy. The fabricated Ti3C2T x -based all-solid-state MSC achieves a high areal capacitance of 25.5 mF cm-2, which benefits from the unique layered structure and high electrical conductivity of the electrode. The fabricated planar MSC also delivers good cycling stability and excellent flexibility. Moreover, our fabrication strategy can be readily extended to other composite films for MSCs and become potential micropower sources for miniaturized electronic devices.

Boosting Lithium Storage Properties of MOF Derivatives through a Wet-Spinning Assembled Fiber Strategy.

Graphene composite fibers are of great importance in constructing electrode materials with high flexibility and conductivity for energy storage and electronic devices. Integration of multifunctional metal-organic frameworks (MOFs) into graphene fiber scaffolds enables novel functions and enhanced physical/chemical properties. The close-packed and aligned graphene sheets along with the porous MOF-derived structures can achieve excellent lithium storage performance through synergetic effects. In this work, a facile and general strategy is demonstrated for the preparation of MOF/graphene oxide (GO) fibers, which serve as precursors for the subsequent preparation of porous metal oxide/reduced graphene oxide (rGO) composite fibers. The obtained composites, for example, porous Fe2 O3 /rGO and Co3 O4 /rGO fibers, possess unique features of MOF-derived porous structures and excellent electrical conductivity. When tested as anode materials for lithium-ion batteries in coin cells, the MOF/GO fiber-derived porous metal oxide/rGO composite fibers exhibited high specific capacity, excellent rate capability and cycling performance. Moreover, a flexible fiber battery was fabricated based on the Fe2 O3 /rGO composite fiber, which demonstrates its potential application for flexible electronic devices.