Unveiling the Failure Mechanism of Zn Anodes in Zinc Trifluorosulfonate Electrolyte: The Role of Micelle-like Structures.

Zinc trifluorosulfonate [Zn(OTf)2] is considered as the most suitable zinc salt for aqueous Zn-ion batteries (AZIBs) but cannot support the long-term cycling of the Zn anode. Here, we reveal the micelle-like structure of the Zn(OTf)2 electrolyte and reunderstand the failing mechanism of the Zn anode. Since the solvated Zn2+ possesses a positive charge, it can spontaneously attract OTf- with the hydrophilic group of -SO3 and the hydrophobic group of -CF3 via electrostatic interaction and form a "micelle-like" structure, which is responsible for the poor desolvation kinetics and dendrite growth. To address these issues, an antimicelle-like structure is designed by using ethylene glycol monomethyl ether (EGME) as a cosolvent for highly reversible AZIBs. The modified electrolyte shows lower dissociation ability to Zn(OTf)2 and higher coordination tendency with Zn2+ compared to the Zn(OTf)2 electrolyte, resulting in the unique solvation structure of Zn2+(H2O)1.2(OTf-)2(EGME)2.8, which significantly reduces the charge of micelle, damages the micelle-like structure, and boosts the desolvation kinetics. Moreover, the reduction of EGME and OTf- can form a robust dual-layered SEI with high Zn2+ ion conductivity. Consequently, the Zn/Cu asymmetric coin cell using ZT-EGME can work at a high rate and a capacity of 50 mA cm-2 and 5 mA h cm-2 for more than 120 cycles, while its counterparts using ZT can barely work. Moreover, a 505.1 mA h pouch cell with practical parameters including a lean electrolyte supply of 15 mL A h-1 and an N/P ratio of ∼3.5 can work for 50 cycles.

Promoting OH- Adsorption and Diffusion Enables Ultrahigh Capacity and Rate Capability of Nickel Sulfide Cathode for Aqueous Alkaline Zn-Based Batteries.

Aqueous alkaline Zn-based batteries (AAZBs) possess great promise for large-scale applications thanks to their higher discharging plateau and unique reaction mechanism. However, the capacity and rate capability of Ni-based cathodes are still unsatisfactory due to their insufficient OH- adsorption and diffusion ability. Herein, heterostructured Ni3 S2 /Ni(OH)2 nanosheets with outstanding electrochemical performance are synthesized via a facile chemical etching strategy. The heterostructured Ni3 S2 /Ni(OH)2 nanosheet cathode shows significantly increased capacity and rate capability due to its boosted OH- adsorption and diffusion ability compared to Ni3 S2 . Consequently, the assembled Zn//Ni3 S2 /Ni(OH)2 cell can deliver an ultrahigh capacity of 2.26 mAh cm-2 , an excellent rate performance (0.91 mAh cm-2 at 100 mA cm-2 ) and a satisfying cycling stability (1.01 mAh cm-2 at 20 mA cm-2 after 500 cycles). Moreover, a prominent energy density of 3.86 mWh cm-2 is obtained, which exceeds the majority of recently reported AAZBs. This work is expected to provide a new modification direction for developing high-performance nickel sulfide cathode for AAZBs.

The effects of water, substrate, and intermediate adsorption on the photocatalytic decomposition of air pollutants over nano-TiO2 photocatalysts.

The photocatalytic performance of nano-TiO2 photocatalysts in air pollutant degradation greatly depends on the adsorption of water, substrates, and intermediates. Especially under excessive humidity, substrate concentration, and intermediate concentration, the competitive adsorption of water, substrates, and intermediates can seriously inhibit the photocatalytic performance. In the past few years, extensive studies have been performed to investigate the influence of humidity, substrate concentration, and intermediates on the photocatalytic performance of TiO2, and significant advances have been made in the area. However, to the best of our knowledge, there is no review focusing on the effects of water, substrate, and intermediate adsorption to date. A comprehensive understanding of their mechanisms is key to overcoming the limited application of nano-TiO2 photocatalysts in the photocatalytic decomposition of air pollutants. In this review, the progress in experimental and theoretical fields, including a recent combination of photocatalytic experiments and adsorption and photocatalytic simulations by density functional theory (DFT), to explore the impact of adsorption of various reaction components on nano-TiO2 photocatalysts is comprehensively summarized. Additionally, the mechanism and broad perspective of the impact of their adsorption on the photocatalytic activity of TiO2 in air treatment are also critically discussed. Finally, several solutions are proposed to resolve the current problems related to environmental factors. In general, this review contributes a comprehensive perspective of water, substrate, and intermediate adsorption toward boosting the photocatalytic application of TiO2 nanomaterials.

Weak Solvation Effect Induced Optimal Interfacial Chemistry Enables Highly Durable Zn Anodes for Aqueous Zn-Ion Batteries.

Aqueous zinc-ion batteries (AZIBs) are emerging as one of the most reliable energy storage technologies for scale-up applications, but still suffer from the instability of Zn anode, which is mainly caused by the undesirable dendrite growth and side reactions. To tackle these issues, we formulate a new aqueous electrolyte with weak solvation effect by introducing low-dielectric-constant acetone to achieve H2 O-poor solvation structure of Zn2+ . Experimental and theoretical calculation studies concurrently reveal that such solvation structure can: i) relieve the solvated H2 O related side reactions, ii) suppress the dendrite growth by boosting the desolvation kinetics of Zn2+ and iii) in situ form solid electrolyte interface (SEI) to synergistically inhibit the side reaction and dendrite growth. The synergy of these three factors prolongs the cycling life of Cu/Zn asymmetric cell from 30 h to more than 800 h at 1 mA cm-2 /1 mAh cm-2 , and can work at more harsh condition of 5 mA cm-2 /5 mAh cm-2 . More encouragingly, Zn/V2 O5 ⋅ nH2 O full cell also shows enhanced cycling stability of 95.9 % capacity retention after 1000 cycles, much better than that with baseline electrolyte (failing at ≈700th  cycle).

Valence Engineering Enhancing NH4 + Storage Capacity of Manganese Oxides.

Ammonium ions (NH4 + ), as non-metallic charge carriers, are attracting attention in aqueous batteries due to its low molar mass, element sufficiency, and non-toxicity. However, the host materials for NH4 + storage are still limited. Herein, an oxygen defects-rich manganese oxide (MnO2-x ) for NH4 + storage are reported. The oxygen defects can endow the MnO2-x sample with improved electric conductivity and low interface activation energy. The electrochemical reaction mechanism is also verified by using ex situ X-ray photoelectron spectroscopy (XPS) and fourier transform infrared spectroscopy (FT-IR), demonstrating the insertion and extraction of NH4 + in the MnO2-x by formation/breaking of a hydrogen bond. As a result, MnO2-x delivers a high capacity of 109.9 mAh g-1 at the current density of 0.5 A g-1 and retention of 24 mAh g-1 after 1000 cycles at the current density of 4 A g-1 , outperforming the pristine MnO2 sample.

Inorganic Sonosensitizers for Sonodynamic Therapy in Cancer Treatment.

The rapid development of nanomedicine and nanobiotechnology has allowed the emergence of various therapeutic modalities with excellent therapeutic efficiency and biosafety, among which, the sonodynamic therapy (SDT), a combination of low-intensity ultrasound and sonosensitizers, is emerging as a promising noninvasive treatment modality for cancer treatment due to its deeper penetration, good patient compliance, and minimal damage to normal tissue. The sonosensitizers are indispensable components in the SDT process because their structure and physicochemical properties are decisive for therapeutic efficacy. Compared to the conventional and mostly studied organic sonosensitizers, inorganic sonosensitizers (noble metal-based, transition metal-based, carbon-based, and silicon-based sonosensitizers) display excellent stability, controllable morphology, and multifunctionality, which greatly expand their application in SDT. In this review, the possible mechanisms of SDT including the cavitation effect and reactive oxygen species generation are briefly discussed. Then, the recent advances in inorganic sonosensitizers are systematically summarized and their formulations and antitumor effects, particularly highlighting the strategies for optimizing the therapeutic efficiency, are outlined. The challenges and future perspectives for developing state-of-the-art sonosensitizers are also discussed. It is expected that this review will shed some light on future screening of decent inorganic sonosensitizers for SDT.

Tendency Regulation of Competing Reactions Toward Highly Reversible Tin Anode for Aqueous Alkaline Batteries.

Investigating dendrite-free stripping/plating anodes is highly significant for advancing the practical application of aqueous alkaline batteries. Sn has been identified as a promising candidate for anode material, but its deposition/dissolution efficiency is hindered by the strong electrostatic repulsion between Sn(OH)3 - and the substrate. Herein, this work constructs a nondense copper layer which serves as stannophile and hydrogen evolution inhibitor to adjust the tendency of competing reactions on Sn foil surface, thus achieving a highly reversible Sn anode. The interactions between the deposited Sn and the substrates are also strengthened to prevent shedding. Notably, the ratio of Sn redox reaction is significantly boosted from ≈20% to ≈100%, which results in outstanding cycling stability over 560 h at 10 mA cm-2 . A Sn//Ni(OH)2 battery device is also demonstrated with capacities from 0.94 to 22.4 mA h cm-2 and maximum stability of 1800 cycles.

Manipulating Molecular Structure to Trigger Ultrafast and Long-Life Potassium Storage of Fe0.4 Ni0.6 S Solid Solution.

Currently, the main obstacle to the widespread utilization of metal chalcogenides (MSx ) as anode for potassium-ion batteries (PIBs) is their poor rate capability and inferior cycling stability as a result of the undesirable electrical conductivity and severe pulverization of the nanostructure during large K-ions intercalation-extraction processes. Herein, an ultrafast and long-life potassium storage of metal chalcogenide is rationally demonstrated by employing Fe0.4 Ni0.6 S solid-solution (FNS/C) through molecular structure engineering. Benefiting from improved electroactivity and intense interactions within the unique solid solution phase, the electrical conductivity and structure durability of Fe0.4 Ni0.6 S are vastly improved. As anticipated, the FNS/C electrode delivers superior rate properties (538.7 and 210.5 mAh g-1 at 0.1 and 10 A g-1 , respectively) and long-term cycle stability (180.8 mAh g-1 at 5 A g-1 after 2000 cycles with a capacity decay of 0.011% per cycle). Moreover, the potassium storage mechanisms of Fe0.4 Ni0.6 S solid solution are comprehensively revealed by several in situ characterizations and theoretical calculations. This innovative molecular structure engineering strategy opens avenues to achieve high-quality metal chalcogenides for future advanced PIBs.

Molecular dynamics of the spontaneous generation mechanism of natural gas hydrates during methane nanobubble rupture.

Natural gas hydrates have garnered significant attention as a potential new source of alternative energy, and understanding their formation mechanism is of paramount importance for efficient utilization and pipeline transportation. However, there is no consensus among academics on the formation mechanism of natural gas hydrates. In this paper, we propose a method for promoting the rapid formation of natural gas hydrates based on the rupture of methane nanobubbles, which creates local high temperature and pressure to facilitate the mixing of methane and water. The rapid decrease in system temperature and pressure during the process further enhances the formation of gas hydrates. Using molecular dynamics simulations, we theoretically verify the formation of natural gas hydrates. Our results indicate that the instantaneous rupture of methane nanobubbles induced by shock waves leads to a dramatic increase in the local molecular motion velocity around the bubbles. This results in extreme local high temperature and high pressure, leading to complete mixing of methane and water and rapid formation of gas hydrates during the cooling and pressure drop of the mixture. We confirm our findings by analyzing F3-order parameters, F4-order parameters, and water cage statistics.

Structural and surface engineering promotes Zn-ion energy storage capability of commercial carbon cloth.

Aqueous Zn-ion hybrid supercapacitors (AZHSCs) combining the advantages of high-energy batteries and high-power supercapacitors see a bright future, but they still suffer from the poor capacity of carbonic cathodes. Herein, a functionalized porous carbon cloth (denoted as FPCC) electrode is demonstrated based on commercial carbon cloth (denoted as CC) tuning by structural and surface engineering. The constructed exfoliated porous carbon layer and the negatively charged functionalized interface not only increase the electrical double layer capacitance but also favor the chemical adsorption of Zn2+ to obtain additional pseudocapacitance. Consequently, the FPCC electrode delivers a high capacity of 0.16 mAh cm-2 at 4 mA cm-2, which is 923.8 times higher than CC, and a long cycle life (85.0% capacity retention after 30 000 cycles). More importantly, the Zn//FPCC AZHSC possesses an impressive energy density (3.3 mWh cm-3) and power density (240 mW cm-3), superior to many advanced batteries and supercapacitors. The quasi-solid-state device is also assembled as a demo. This modification strategy may provide new opportunities for high-performance AZHSCs.

One-Pot Synthesis of NiSe2 with Layered Structure for Nickel-Zinc Battery.

Transition metal organic framework materials and their selenides are considered to be one of the most promising cathode materials for nickel-zinc (denoted as Ni-Zn) batteries due to their low cost, environmental friendliness, and controllable microstructure. Yet, their low capacity and poor cycling performance severely restricts their further development. Herein, we developed a simple one-pot hydrothermal process to directly synthesize NiSe2 (denotes as NiSe2-X based on the molar amount of SeO2 added) stacked layered sheets. Benefiting from the peculiar architectures, the fabricated NiSe2-1//Zn battery based on NiSe2 and the Zn plate exhibits a high specific capacity of 231.6 mAh g-1 at 1 A g-1, and excellent rate performance (162.8 mAh g-1 at 10 A g-1). In addition, the NiSe2//Zn battery also presents a satisfactory cycle life at the high current density of 8 A g-1 (almost no decay compared to the initial specific capacity after 1000 cycles). Additionally, the battery device also exhibits a satisfactory energy density of 343.2 Wh kg-1 and a peak power density of 11.7 kW kg-1. This work provides a simple attempt to design a high-performance layered cathode material for aqueous Ni-Zn batteries.

CoP Nanoparticle Confined in P, N Co-Doped Porous Carbon Anchored on P-Doped Carbonized Wood Fibers with Tailored Electronic Structure for Efficient Urea Electro-Oxidation.

Electronic structure optimization and architecture modulation are widely regarded as rational strategies to enhance the electrocatalysts catalytic performance. Herein, a hybridization of ZIF-67-derived CoP nanoparticles embedded in P, N co-doped carbon matrix (PNC) and anchored on P-doped carbonized wood fibers (PCWF) is constructed using a simple simultaneous phosphorization and carbonization strategy. Benefiting from the optimized surface/interface electronic structures, abundant exposed active sites, and outstanding conductivity, the CoP@PNC/PCWF can drive the urea oxidation reaction (UOR) with greater activity and better stability than most recently reported electrocatalysts, in which a potential as low as 1.32 V (vs reversible hydrogen electrode, RHE) is needed to reach 50 mA cm-2 and shows excellent durability. Furthermore, for overall urea splitting, using the CoP@PNC/PCWF electrocatalyst as the anode and commercial Pt/C supported on nickel foam as the cathode, an ultralow cell voltage of 1.50 V (vs RHE) is expected to achieve the 50 mA cm-2 and operate continuously for more than 50 h at 20 mA cm-2 . The reported strategy may shed light on the use of renewable resources to design and synthesize high-performance non-Ni-based phosphides UOR electrocatalysts for energy-saving H2 production.

Recent Advances of Carbon Materials in Anodes for Aqueous Zinc Ion Batteries.

Carbon-based materials have been successfully applied in the zinc ion batteries to improve the energy storage capability and durability of zinc anodes. In this review, four types of carbon materials (conventional carbons, fiber-like carbons, carbon nanotubes, graphene and other 2D carbon materials) are introduced based on the electrode preparation, physicochemical property and battery performance. Several modification strategies are also illustrated, such as heteroatom doping, hierarchical design and metal/carbon composites. Besides the discussion of existing issues of zinc anodes, the structure-performance relationships are analyzed in depth. Finally, conclusive remarks of this review are summarized and prospects of the future improvement are proposed.

Ten Thousand-Cycle Ultrafast Energy Storage of Wadsley-Roth Phase Fe-Nb Oxides with a Desolvation Promoting Interfacial Layer.

Developing advanced electrode materials with enhanced charge-transfer kinetics is the key to realizing fast energy storage technologies. Commonly used modification strategies, such as nanoengineering and carbon coating, are mainly focused on electron transfer and bulk Li+ diffusion. Nonetheless, the desolvation behavior, which is considered as the rate-limiting process for charge-storage, is rarely studied. Herein, we designed a nitridation layer on the surface of Wadsley-Roth phase FeNb11O29 (FNO-x@N) to act as a desolvation promoter. Theoretical calculations demonstrate that the adsorption and desolvation of solvated Li+ is efficiently improved at FNO-x@N/electrolyte interphase, leading to the reduced desolvation energy barrier. Moreover, the nitridation layer can also help to prevent solvent cointercalation during Li+ insertion, leading to advantageous shrinkage of block area and reduced volume change of lattice cell during cycling. Consequently, FNO-x@N exhibits a high-rate capacity of 129.7 mAh g-1 with negligible capacity decay for 10 000 cycles.

Printing Porous Carbon Aerogels for Low Temperature Supercapacitors.

Maintaining fast charging capability at low temperatures represents a significant challenge for supercapacitors. The performance of conventional porous carbon electrodes often deteriorates quickly with the decrease of temperature due to sluggish ion and charge transport. Here we fabricate a 3D-printed multiscale porous carbon aerogel (3D-MCA) via a unique combination of chemical methods and the direct ink writing technique. 3D-MCA has an open porous structure with a large surface area of ∼1750 m2 g-1. At -70 °C, the symmetric device achieves outstanding capacitance of 148.6 F g-1 at 5 mV s-1. Significantly, it retains a capacitance of 71.4 F g-1 at a high scan rate of 200 mV s-1, which is 6.5 times higher than the non-3D printed MCA. These values rank among the best results reported for low temperature supercapacitors. These impressive results highlight the essential role of open porous structures for preserving capacitive performance at ultralow temperatures.

Unshared Pair Electrons of Zincophilic Lewis Base Enable Long-life Zn Anodes under "Three High" Conditions.

The hydrogen evolution and dendrite issues are the notorious culprits of the limited lifespan and Coulombic efficiency (CE) of Zn anodes, particularly at harsh test conditions. Herein, considering the Lewis acidic feature of Zn2+ , abundant unshared pair electrons of zincophilic Lewis bases are proposed as decent electrolyte additives to stabilize Zn anodes at "Three High" conditions (high depth of discharge, high areal capacity and high current). The unshared pair electrons can remove H2 O from Zn2+ solvated sheaths and confine the activity of H2 O by breaking its hydrogen bonding network. The combination of these factors effectively restricts H2 O-involved side reactions and enables dendrite-free Zn deposition, even at harsh conditions. The effectiveness of this strategy is fully proved by a series of Lewis base molecules. Noticeably, the Zn||Zn cell with an area of 20 cm2 , using DMF-containing electrolyte can be stably cycled over 1000 h at 60 % DOD, with a 100 % CE.

Compacting Electric Double Layer Enables Carbon Electrode with Ultrahigh Zn Ion Storage Capability.

Carbon-based cathodes for aqueous zinc ion hybrid supercapacitors (ZHSCs) typically undergo low Zn ion storage capability due to their electric double layer capacitance (EDLC) energy storage mechanism that is restricted by specific surface area and thickness of electric double layer (EDL). Here, we report a universal surface charge modulation strategy to effectively enhance the capacitance of carbon materials by decreasing the thickness of EDL. Amino groups with lone pair electrons were chosen to increase the surface charge density and enhanced the interaction between carbon electrode and Zn ions, thus effectively compacting the EDL. Consequently, amino functionalized porous carbon based ZHSCs can deliver an ultrahigh capacity of 255.2 mAh g-1 along with excellent cycling stability (95.5 % capacity retention after 50 000 cycles) in 1 M ZnCl2 electrolyte. This study demonstrates the feasibility of EDL modified carbon as Zn2+ storage cathode and great prospect for constructing high performance ZHSCs.

Linker Defects Triggering Boosted Oxygen Reduction Activity of Co/Zn-ZIF Nanosheet Arrays for Rechargeable Zn-Air batteries.

The poor electronic conductivity and low intrinsically electrocatalytic activity of most metal-organic frameworks (MOFs) greatly limit their direct applications as oxygen reduction reaction (ORR) electrocatalysts. In this work, it is reported that introduction of linker defects can effectively trigger the ORR activity of leaf-shaped zeolitic imidazolate framework (ZIF) by increasing the intrinsic activity of metal sites and electrical conductivity. Experimental results show that part of imidazole molecules is successfully removed from ZIF after a low-temperature thermal treatment without destroying its structure integrity, resulting in the formation of unsaturated metal sites and faster electron transport rate. Consequently, the ZIF with imidazole molecules defects (D-ZIF) exhibits a superior ORR activity than the pristine ZIF, possessing an onset potential of 0.86 V and higher half-wave potential of 0.60 V. Furthermore, the home-made Zn-air batteries with D-ZIF as air cathode exhibit high open-circuit voltage and well cycling stability. The developed linker-deficient modulation strategy can provide a new prospect to enable MOF-based electrocatalysts with efficient catalytic activity.

Enhancing Li-Ion Affinity of Molybdenum Dioxide/Carbon Fabric to Achieve High Pseudocapacitance.

High-energy electrodes at high mass loadings (usually >8.0 mg cm-2 ) are desired for aqueous pseudocapacitors. Yet, how to overcome the thickness-dependent resistance increase of ion/electron transport in pseudocapacitive materials is still challenging. Herein, a high-performance electrode (denoted as AMC) adapted to high mass loading is achieved by promoting the Li-ion affinity of 3D MoO2 /carbon fabric. The experimental results and corresponding computational results reveal that the oxygen-activated surface of AMC, combined with the wettability and conductivity superiority of 3D graphite network, significantly facilitates the Li-ion adsorption and diffusion at the electrode/electrolyte interface, even at large thicknesses. Consequently, even at a high mass loading up to 8.1 mg cm-2 , the AMC electrode also displays an impressive specific capacity (567.5 C g-1 at 2.5 A g-1 ), substantially superior to most advanced pseudocapacitive electrodes. The strategy of boosting energy characteristic by enhancing the affinity of charge carriers is applicable to other pseudocapacitive electrodes.

Mo2 C/Reduced Graphene Oxide Composites with Enhanced Electrocatalytic Activity and Biocompatibility for Microbial Fuel Cells.

A simple, cost-effective strategy was developed to effectively improve the electron transfer efficiency as well as the power output of microbial fuel cells (MFCs) by decorating the commercial carbon paper (CP) anode with an advanced Mo2 C/reduced graphene oxide (Mo2 C/RGO) composite. Benefiting from the synergistic effects of the superior electrocatalytic activity of Mo2 C, the high surface area, and prominent conductivity of RGO, the MFC equipped with this Mo2 C/RGO composite yielded a remarkable output power density of 1747±37.6 mW m-2 , which was considerably higher than that of CP-MFC (926.8±6.3 mW m-2 ). Importantly, the composite also facilitated the formation of 3D hybrid biofilm and could effectively improve the bacteria-electrode interaction. These features resulted in an enhanced coulombic efficiency up 13.2 %, nearly one order of magnitude higher than that of the CP (1.2 %).