Unveiling activation mechanism of persulfate by homologous hemp-derived biochar catalysts for enhanced tetracycline wastewater remediation.

Advancements in biochar activating persulfate advanced oxidation processes (PS-AOP), have gained significant attention. However, the understanding of biochar-based catalysts in activating PS remains limited. Herein, biochar (BC) and N-doped biochar (NBC) were synthesized from hemp for activating PS to treat tetracycline (TC) wastewater and analyzed their mechanisms separately. Surprisingly, N-doped in biochar leads to a change in the activation mechanism of PS. The BC-PS system operates mainly through a radical pathway, advantageous for treating soil organic pollution (68%) with pH adaptability (less than 10% variation). Nevertheless, the NBC-PS system primarily employs an electron transfer non-radical pathway, demonstrating stability (only 7% performance degradation over four cycles) and enhanced resistance to anionic interference (less than 10% variation) in organic wastewater treatment. This study provides a technical reference and theoretical foundation for enhancing biochar activation of PS in the removal of organic pollutants from aquatic and terrestrial environments.

Complementary Weaknesses: A Win-Win Approach for rGO/CdS to Improve the Energy Conversion Performance of Integrated Photorechargeable Li-S Batteries.

Integrating solar energy into rechargeable battery systems represents a significant advancement towards sustainable energy storage solutions. Herein, we propose a win-win solution to reduce the shuttle effect of polysulfide and improve the photocorrosion stability of CdS, thereby enhancing the energy conversion efficiency of rGO/CdS-based photorechargeable integrated lithium-sulfur batteries (PRLSBs). Experimental results show that CdS can effectively anchor polysulfide under sunlight irradiation for 20 minutes. Under a high current density (1 C), the discharge-specific capacity of the PRLSBs increased to 971.30 mAh g-1, which is 113.3 % enhancement compared to that of under dark condition (857.49 mAh g-1). Remarkably, without an electrical power supply, the PRLSBs can maintain a 21 hours discharge process following merely 1.5 hours of light irradiation, achieving a breakthrough solar-to-electrical energy conversion efficiency of up to 5.04 %. Ex situ X-ray photoelectron spectroscopy (XPS) and in situ Raman analysis corroborate the effectiveness of this complementary weakness approach in bolstering redox kinetics and curtailing polysulfide dissolution in PRLSBs. This work showcases a feasible strategy to develop PRLSBs with potential dual-functional metal sulfide photoelectrodes, which will be of great interest in future-oriented off-grid photocell systems.

Unveiling the Synergistic Role of Frustrated Lewis Pairs in Carbon-Encapsulated Ni/NiOx Photothermal Cocatalyst for Enhanced Photocatalytic Hydrogen Production.

The development of high-density and closely spaced frustrated Lewis pairs (FLPs) is crucial for enhancing catalyst activity and accelerating reaction rates. However, constructing efficient FLPs by breaking classical Lewis bonds poses a significant challenge. Here, this work has made a pivotal discovery regarding the Jahn-Teller effect during the formation of grain boundaries in carbon-encapsulated Ni/NiOx (Ni/NiOx@C). This effect facilitates the formation of high-density O (VO) and Ni (VNi) vacancy sites with different charge polarities, specifically FLP-VO-C basic sites and FLP-VNi-C acidic sites. The synergistic interaction between FLP-VO-C and FLP-VNi-C sites not only reduces energy barriers for water adsorption and splitting, but also induces a strong photothermal effect. This mutually reinforcing effect contributes to the exceptional performance of Ni/NiOx@C as a cocatalyst in photothermal-assisted photocatalytic hydrogen production. Notably, the Ni/NiOx@C/g-C3N4 (NOCC) composite photocatalyst exhibits remarkable hydrogen production activity with a rate of 10.7 mmol g-1 h-1, surpassing that of the Pt cocatalyst by 1.76 times. Moreover, the NOCC achieves an impressive apparent quantum yield of 40.78% at a wavelength of 380 nm. This work paves the way for designing novel defect-state multiphase cocatalysts with high-density and adjacent FLP sites, which hold promise for enhancing various catalytic reactions.

Bifunctional Ni Foam Supported TiO2 @Ni3 S2 core@shell Nanorod Arrays for Boosting Electrocatalytic Biomass Upgrading and H2 Production Reactions.

Replacing traditional oxygen evoltion reaction (OER) with biomass oxidation reaction (BOR) is an advantageous alternative choice to obtain green hydrogen energy from electrocatalytic water splitting. Herein, a novel of extremely homogeneous Ni3 S2 nanosheets covered TiO2 nanorod arrays are in situ growth on conductive Ni foam (Ni/TiO2 @Ni3 S2 ). The Ni/TiO2 @Ni3 S2 electrode exhibits excellent electrocatalytic activity and long-term stability for both BOR and hydrogen evolution reaction (HER). Especially, taking glucose as a typical biomass, the average hydrogen production rate of the HER-glucose oxidation reaction (GOR) two-electrode system reached 984.74 µmol h-1 , about 2.7 times higher than that of in a common HER//OER two-electrode water splitting system (365.50 µmol h-1 ). The calculated power energy saving efficiency of the GOR//HER system is about 13% less than that of the OER//HER system. Meanwhile, the corresponding selectivity of the value-added formic acid produced by GOR reaches about 80%. Moreover, the Ni/TiO2 @Ni3 S2 electrode also exhibits excellent electrocatalytic activity on a diverse range of typical biomass intermediates, such as urea, sucrose, fructose, furfuryl alcohol (FFA), 5-hydroxymethylfurfural (HMF), and alcohol (EtOH). These results show that Ni/TiO2 @Ni3 S2 has great potential in electrocatalysis, especially in replacing OER reaction with BOR reaction and promoting the sustainable development of hydrogen production.

Synergistic Bimetallic CoCu-Codecorated Carbon Nanosheet Arrays as Integrated Bifunctional Cathodes for High-Performance Rechargeable/Flexible Zinc-Air Batteries.

The unremitting exploration of well-architectured and high-efficiency oxygen electrocatalysts is promising to speed up the surface-mediated oxygen reduction/evolution reaction (ORR/OER) kinetics of rechargeable zinc-air batteries (ZABs). Herein, bimetallic CoCu-codecorated carbon nanosheet arrays (CoCu/N-CNS) are proposed as self-supported bifunctional oxygen catalysts. The integrated catalysts are in situ constructed via a simple sacrificial-templated strategy, imparting CoCu/N-CNS with 3D interconnected conductive pathways, abundant mesopores for electrolyte penetration and ion diffusion, as well as Cu-synergized Co-Nx /O reactive sites for improved catalytic activities. By incorporating a moderate amount of Cu into CoCu/N-CNS, the bifunctional activities can be further increased due to synergistic oxygen electrocatalysis. Consequently, the optimized CoCu/N-CNS realizes a low overall overpotential of 0.64 V for OER and ORR and leads to high-performance liquid ZABs with high gravimetric energy (879.7 Wh kg-1 ), high peak power density (104.3 mW cm-2 ), and remarkable cyclic stability upon 400 h/1000 cycles at 10 mA cm-2 . More impressively, all-solid-state flexible ZABs assembled with the CoCu/N-CNS cathode exhibit superior rate performance and exceptional mechanical flexibility under arbitrary bending conditions. This CoCu/N-CNS monolith holds significant potential in advancing cation-modulated multimetallic electrocatalysts and multifunctional nanocatalysts.

Efficient purification of tetracycline wastewater by activated persulfate with heterogeneous Co-V bimetallic oxides.

The persistence and wide dispersion of antibiotics have a severe impact on the ecological environment. Developing an effective method with universal applicability to remove pollutants is pretty necessary. Herein, a bimetallic oxides (Co3V2O8) heterogeneous material was successfully prepared and used to activate the persulfate (PS) for purification of tetracycline (TC) wastewater. By exploring the reaction conditions and influencing factors, the removal rate of 50 mg⋅L-1 TC reached 87.1% by Co3V2O8/PS system, and the reaction rate constant was up to 0.0271 min-1. As a highly efficient catalyst for the activation of PS, Co3V2O8/PS system produces radicals of SO4•-, •OH, •O2- and 1O2 in the reaction process due to the Co(II) and V(IV) exchange electrons with S2O82- and O2. Simultaneously, the internal electron exchange occurs between Co(II)/Co(III) and V(IV)/V(V), which stabilizes the content of Co(II) and V(IV). This work provides a novel activator for PS activation to degrade contaminants and contributes to a better understanding of the PS activation mechanism by transition compound.

Boosting CdS Photocatalytic Activity for Hydrogen Evolution in Formic Acid Solution by P Doping and MoS2 Photodeposition.

Formic acid is an appealing hydrogen storage material. In order to rapidly produce hydrogen from formic acid under relatively mild conditions, high-efficiency and stable photocatalytic systems are of great significance to prompt hydrogen (H2) evolution from formic acid. In this paper, an efficient and stable photocatalytic system (CdS/P/MoS2) for H2 production from formic acid is successfully constructed by elemental P doping of CdS nanorods combining with in situ photodeposition of MoS2. In this system, P doping reduces the band gap of CdS for enhanced light absorption, as well as promoting the separation of photogenerated charge carriers. More importantly, MoS2 nanoparticles decorated on P-doped CdS nanorods can play as noble-metal-free cocatalysts, which increase the light adsorption, facilitate the charge transfer and effectively accelerate the hydrogen evolution reaction. Consequently, the apparent quantum efficiency (AQE) of the designed CdS/P/MoS2 is up to 6.39% at 420 nm, while the H2 evolution rate is boosted to 68.89 mmol·g-1·h-1, which is 10 times higher than that of pristine CdS. This study could provide an alternative strategy for the development of competitive CdS-based photocatalysts as well as noble-metal-free photocatalytic systems toward efficient hydrogen production.

Phase-Controllable Growth Nix Py Modified CdS@Ni3 S2 Electrodes for Efficient Electrocatalytic and Enhanced Photoassisted Electrocatalytic Overall Water Splitting.

The rational design and construction of cost-effective nickel-based phosphide or sulfide (photo)electrocatalysts for hydrogen production from water splitting has sparked a huge investigation surge in recent years. Whereas, nickel phosphides (Nix Py ) possess more than ten stoichiometric compositions with different crystalline. Constructing Nix Py with well crystalline and revealing their intrinsic catalytic mechanism at atomic/molecular levels remains a great challenge. Herein, an easy-to-follow phase-controllable phosphating strategy is first proposed to prepare well crystalline Nix Py (Ni3 P and Ni12 P5 ) modified CdS@Ni3 S2 heterojunction electrocatalysts. It is found that Ni3 P modified CdS@Ni3 S2 (CdS@Ni3 S2 /Ni3 P) exhibits remarkable stability and bifunctional electrocatalytic activities in both hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). Density functional theory results suggest that P-Ni sites and P sites in CdS@Ni3 S2 /Ni3 P, respectively, serve as OER and HER active sites during electrocatalytic water splitting processes. Moreover, benefiting from the advantageous photocatalyst@electrocatalyst core@shell structure, CdS@Ni3 S2 /Ni3 P delivers an advantaged photoassisted electrocatalytic water splitting property. The champion electrical to hydrogen and solar to hydrogen energy conversion efficiencies of CdS@Ni3 S2 /Ni3 P, respectively, reach 93.35% and 4.65%. This work will provide a general guidance for synergistically using solar energy and electric energy for large-scale H2 production from water splitting.

A CuNi Alloy-Carbon Layer Core-Shell Catalyst for Highly Efficient Conversion of Aqueous Formaldehyde to Hydrogen at Room Temperature.

A copper (Cu) material is catalytically active for formaldehyde (HCHO) dehydrogenation to produce H2, but the unsatisfactory efficiency and easy corrosion hinder its practical application. Alloying with other metals and coating a carbon layer outside are recognized as effective strategies to improve the catalytic activity and the long-term durability of nonprecious metal catalysts. Here, highly dispersed CuNi alloy-carbon layer core-shell nanoparticles (CuNi@C) have been developed as a robust catalyst for efficient H2 generation from HCHO aqueous solution at room temperature. Under the optimized reaction conditions, the CuNi@C catalyst exhibits a H2 evolution rate of 110.98 mmol·h-1·g-1, which is 1.5 and 4.9 times higher than those of Cu@C and Ni@C, respectively, which ranks top among the reported nonprecious metal catalysts for catalytic HCHO reforming at room temperature to date. Furthermore, CuNi@C also displays excellent stability toward the catalytic HCHO reforming into H2 in tap water owing to the well-constructed carbon sheath protecting CuNi nanocrystals from oxidation in an alkaline medium. Combined with density functional theory calculations, the superior catalytic efficiency of CuNi@C for H2 generation results from the synergistic contribution between the massive active species from HCHO decomposition on the Cu sites and the remarkable H2 evolution activity on Ni sites. The improved performance of CuNi@C highlights the enormous potential of advancing noble-metal-free nanoalloys as cost-effective and recyclable catalysts for energy recovery from industrial HCHO wastewater.

Vanadium Nitride Quantum Dots/Holey Graphene Matrix Boosting Adsorption and Conversion Reaction Kinetics for High-Performance Lithium-Sulfur Batteries.

Lithium-sulfur batteries (LSBs) have been considered as potential next-generation energy storage systems due to their high specific energy of 2600 Wh kg-1 and 2800 Wh L-1. Nevertheless, the practical application of LSBs still faces several hazards, including the shuttle effect of soluble lithium polysulfides, low electrical conductivities of solid sulfur and lithium sulfides, and large volume expansion during charge/discharge cycles. To address this critical challenge, we innovatively proposed facile synthesis of nanostructured VN quantum dots (VNQD)/holey graphene matrix for stabilizing the sulfur cathode by simultaneously promoting the trapping, anchoring, and catalyzing efficiencies of both LiPSs and Li2S. Benefiting from abundant edge catalytic sites of VNQD, in-plane nanopores of graphene, and high electrical conductivity, the sulfur host not only provides high adsorption capability toward soluble polysulfides, strong binding ability for anchoring solid Li2S, and their rapid conversion kinetics but also contributes abundant sulfur storage sites and efficient transport pathways for lithium ions (Li+) and electrons. Consequently, the sulfur cathode exhibits high initial capacities of 1320 mAh g-1, high rate capability (850 mAh g-1 @ 4 mA cm-2), and high capacity retention of 99.95% per cycle after 500 cycles, providing a feasible solution for the practical utilization of shuttle-free Li-S batteries.

Improving the Efficiency of Quantum Dot Sensitized Solar Cells beyond 15% via Secondary Deposition.

Low loading is one of the bottlenecks limiting the performance of quantum dot sensitized solar cells (QDSCs). Although previous QD secondary deposition relying on electrostatic interaction can improve QD loading, due to the introduction of new recombination centers, it is not capable of enhancing the photovoltage and fill factor. Herein, without the introduction of new recombination centers, a convenient QD secondary deposition approach is developed by creating new adsorption sites via the formation of a metal oxyhydroxide layer around QD presensitized photoanodes. MgCl2 solution treated Zn-Cu-In-S-Se (ZCISSe) QD sensitized TiO2 film electrodes have been chosen as a model device to investigate this secondary deposition approach. The experimental results demonstrate that additional 38% of the QDs are immobilized on the photoanode as a single layer. Due to the increased QD loading and concomitant enhanced light-harvesting capacity and reduced charge recombination, not only photocurrent but also photovoltage and fill factor have been remarkably enhanced. The average PCE of resulted ZCISSe QDSCs is boosted to 15.31% (Jsc = 26.52 mA cm-2, Voc = 0.802 V, FF = 0.720), from the original 13.54% (Jsc = 24.23 mA cm-2, Voc = 0.789 V, FF = 0.708). Furthermore, a new certified PCE record of 15.20% has been obtained for liquid-junction QDSCs.

Antioxidative Stannous Oxalate Derived Lead-Free Stable CsSnX3 (X=Cl, Br, and I) Perovskite Nanocrystals.

Lead-free CsSnX3 perovskite NCs are becoming a promising alternative to CsPbX3 (X=Cl, Br, I), but suffer from extremely poor stability. Herein, we highlight the significant effect of SnII precursors used in the synthesis on the stability of the resultant CsSnX3 NCs. A method is proposed for synthesizing CsSnX3 NCs using Cs2 CO3 , SnC2 O4 , and NH4 X as corresponding constituent precursors, wherein the ratio of reactants can be easily adjusted. Stable CsSnX3 NCs can be obtained with the use of antioxidative SnC2 O4 as the SnII precursor. Experimental results show that the improvement of NCs stability is mainly ascribed to the role of oxalate in the SnC2 O4 precursor. Oxalate ion has a strong antioxidative ability and can effectively inhibit the oxidation of SnII during the synthesis. Besides, oxalate as a bidentate capping ligand is shown to be coordinated on the surface of formed NCs. This can not only passivate the uncoordinated Sn on the surface but also prevent the oxidation of the NCs.

Enhancing Adsorption and Reaction Kinetics of Polysulfides Using CoP-Coated N-Doped Mesoporous Carbon for High-Energy-Density Lithium-Sulfur Batteries.

Lithium-sulfur (Li-S) batteries have shown great potential in the next-generation energy storage devices due to high theoretical energy density and low cost. To obtain high-performance Li-S batteries, it is important to inhibit the polysulfide shuttle effect and improve the reaction kinetics of polysulfides. Herein, CoP nanoparticles coated by metal-organic framework-derived N-doped mesoporous carbon (CoP@N-C) composites are synthesized and applied in both a cathode for a sulfur host and a modified layer on a separator for high-energy-density Li-S batteries since the CoP component has strong chemical anchoring capability toward soluble polysulfides and high electrochemical activity toward polysulfides transformation. Meanwhile, the porous structure of conductive N-doped mesoporous carbon can not only buffer the volume variation of sulfur during the charge/discharge process but also enhance the charge transport rate in the cathode. The constructed batteries have demonstrated a high specific capacity of 1222 mAh g-1 (8.6 mAh cm-2) with a high sulfur areal loading of ∼7.0 mg cm-2 on cathodes, and a mass loading of 0.35 mg cm-2 for modified layer on separators. Its average capacity decay is only 0.076% per cycle after 100 cycles. This work presents the highly competitive performance of Li-S batteries on the areal capacity and capacity decay.

In Situ Photodeposited Construction of Pt-CdS/g-C3N4-MnOx Composite Photocatalyst for Efficient Visible-Light-Driven Overall Water Splitting.

For converting the renewable solar energy to hydrogen (H2) energy by photocatalytic (PC) overall water splitting (OWS), visible-light-driven photocatalysts are especially desired. Herein, a model CdS/g-C3N4 photocatalyst with a type II heterojunction is first demonstrated via a facile coupling of g-C3N4 nanosheets and CdS nanorods. After being combined with in situ photodeposited 3 wt % Pt and 4 wt % MnOx dual cocatalysts simultaneously, the optimal visible-light-driven (λ > 400 nm) composite photocatalyst of Pt-CdS/g-C3N4-MnOx gives a H2 generation rate of 9.244 µmol h-1 (924.4 µmol h-1 g-1) and a O2 evolution rate of 4.6 µmol h-1 (460 µmol h-1 g-1) in pure water, which is over 420 times higher than that of pure CdS nanorods loaded with 0.5 wt % Pt. The apparent quantum efficiency (AQE) reaches about 3.389% (at 400 nm) and 1.745% (at 420 nm), respectively. The combination of a type II heterojunction and simultaneous in situ photodeposition of the dual cocatalysts results in a dramatically improved PC efficiency and a long-term stability of the CdS/g-C3N4 visible-light-driven photocatalyst for OWS.

Enhanced Photogenerated Electron Transfer in a Semiartificial Photosynthesis System Based on Highly Dispersed Titanium Oxide Nanoparticles.

In this study, a hybrid semiartificial photosynthesis system based on chloroplast (CLP) and titanium oxide nanoparticles (TiO2 NPs) was constructed. 2,6-Dichlorophenolindophenol (DCPIP) reduction by TiO2/CLP complex and methylene blue (MB) reduction by TiO2 were used to determine enhanced photogenerated electron transfer in this hybrid system. The DCPIP reduction by the TiO2/CLP complex showed the same trend as MB reduction by TiO2 as a function of concentration of TiO2 NPs, indicating interception of photogenerated electrons in TiO2 by CLP that leads to enhanced photosynthesis efficiency. Decreased photoluminescence intensity and shortened excited-state lifetime of the TiO2/CLP complex compared to that of pure TiO2 also support electron transfer from TiO2 to CLP. Longer visible light absorption wavelength and increasing valence band edges reveal the narrower band gap of TiO2/CLP, which finally results in the enhanced electron transfer from TiO2 to CLP. Higher ferricyanide reduction and enhanced ATP formation with the TiO2/CLP complex demonstrate the accelerated electron-transfer rate of the electron-transfer chain. This study reveals the mechanism of how TiO2 interacts with CLP to enhance the photosynthesis via constructing a semiartificial photosynthesis system.

Strong adsorption of tetracycline hydrochloride on magnetic carbon-coated cobalt oxide nanoparticles.

The overuse of antibiotics, including tetracycline hydrochloride (TC), seriously threatens human health and ecosystems. In this work, magnetic carbon-coated cobalt oxide nanoparticles (CoO@C) were prepared by one-step annealing method and used as an adsorbent for efficient removal of TC from aqueous solution. The characteristic of the materials was studied by SEM, TEM, and XRD, revealing CoO nanoparticles (≤10 nm) were coated by carbon layer. Several influencial parameters, such as annealing temperature and pH on adsorption of TC, were explored, and found that the maximum adsorption capacity of CoO@C on TC reached as high as 769.43 mg g-1. Furthermore, CoO@C displayed excellent stability and reusability. After four repeated use of the adsorbent, the adsorption capacity still remained at 90% of the initial capacity. The pseudo-second order model and Temkin model proved that it was an exothermic chemical adsorption process. Furthermore, after analysis of FT-IR, Zeta-potential, XPS, the positive charge on the surface of CoO@C forms a strong electrostatic interaction with TC, and in addition, a surface bond is formed between the adsorbent and the TC molecule. This work provides a novel and efficient adsorbent for the purification of TC-containing wastewater.

Modified Graphitic Carbon Nitride Nanosheets for Efficient Photocatalytic Hydrogen Evolution.

Considerable research efforts have been devoted to develop noble-metal-free cocatalysts coupled with semiconductors for highly efficient photocatalytic H2 evolution as part of the challenge toward solar-to-fuel conversion. Herein, a new cocatalyst with excellent activity in the electrocatalytic H2 evolution reaction (HER) that is based on Co sheathed in N-doped graphitic carbon nanosheets (Co@NC) was fabricated by a surfactant-assisted pyrolysis approach and then coupled with g-C3 N4 nanosheets to construct a 2 D-2 D g-C3 N4 /Co@NC composite photocatalyst by a simple grinding method. As a result of advantages in effective electrocatalytic HER activity, suitable electronic band structure, and rapid interfacial charge transfer brought about by the 2 D-2 D spatial configuration, the g-C3 N4 /Co@NC photocatalyst that contained 4 wt % Co@NC presented a high photocatalytic H2 generation rate of 15.67 µmol h-1 under visible-light irradiation (λ≥400 nm), which was 104.5 times higher than that of pristine g-C3 N4 . The optimum g-C3 N4 /Co@NC photocatalyst showed a high apparent quantum efficiency of 10.82 % at λ=400 nm.

Ternary Monolithic ZnS/CdS/rGO Photomembrane with Desirable Charge Separation/Transfer Routes for Effective Photocatalytic and Photoelectrochemical Hydrogen Generation.

Highly efficient and easy recyclable monolithic photocatalysts with ideal separation/transport route for photogenerated charge carriers are much desired. In this work, a ZnO seed-induced growth approach is developed to fabricate a ternary monolithic photomembrane, that is, ZnS/CdS heterojunction nanorods in situ grow into the interspaces of multilayer reduced graphene oxide (rGO) sheets (denoted as ZnS/CdS/rGO). The monolithic ZnS/CdS/rGO photomembrane can serve as an efficient visible-light photoactive membrane for photocatalytic (PC) or photoelectrochemical (PEC) hydrogen generation. The fast electron transport of 1D CdS nanorods, the excellent electronic conductivity of multilayer stacked rGO sheets, the intense visible-light absorption of CdS, the unique hierarchical structure, and double heterojunctions (ZnS/CdS and CdS/rGO) efficiently boost the photogenerated electron-hole pairs separation and transfer across the interfacial domain of the photomembrane under visible-light irradiation. Furthermore, the superior stability and reusability of the photomembrane is achieved by the ideal process of photogenerated electron-hole pair separation/transfer, i.e., holes transfer to ZnS and electrons transfer to rGO to inhibit CdS from photocorrosion.

Rational Design and Controllable Synthesis of Multishelled Fe2O3@SnO2@C Nanotubes as Advanced Anode Material for Lithium-/Sodium-Ion Batteries.

Hierarchical Fe2O3 and SnO2 nanostructures have shown great potential for applications in high-performance ion batteries because of their superiority, including wide resources, facile preparation, environmental friendliness, and high energy density. However, some severe challenges, such as rapid capacity decay due to volume expansion upon cycling and poor conductivity, limit their rate performance. To address this issue, multishelled Fe2O3@SnO2@C (FSC) nanotubes were designed and synthesized by using a template method and Ostwald interaction. The as-prepared FSC nanotubes can deliver a high capacity of 1659 mA h g-1 at a current density of 200 mA g-1 and a high reversible capacity of 818 mA h g-1 at 2000 mA g-1 for lithium-ion batteries. Particularly, a high specific capacity of 1024 mA h g-1 is still maintained after 100 charging/discharging cycles at 200 mA g-1. Applied in sodium-ion batteries, the multishelled FSC nanotubes manifest a high specific capacity of 449 mA h g-1 after 180 cycles at 50 mA g-1. Such excellent performances of the as-fabricated FSC nanotubes may be due to the unique multishelled tubular structure, porous characteristics, and high specific surface area. Therefore, the present work provides an outstanding method to improve the energy storage performance of metal oxide composites and other types of nanocomposites.

Simultaneous Encapsulation of Nano-Si in Redox Assembled rGO Film as Binder-Free Anode for Flexible/Bendable Lithium-Ion Batteries.

The emerging ubiquitous flexible/wearable electronics are in high demand for compatible flexible/high-energy rechargeable batteries, which set a collaborative goal to promote the electrochemical performance and the mechanical strength of the fundamental flexible electrodes involved. Herein, freestanding flexible electrode of Si/graphene films is proposed, which is fabricated through a scalable, zinc-driven redox layer-by-layer assembly process. In the hybrid films, silicon nanoparticles are intimately encapsulated and confined in multilayered reduced graphene oxide (rGO) nanosheet films. The designed monolithic rGO/Si film possesses several structural benefits such as high mechanical integrity and three-dimensional conductive framework for accessible charge transport and Li+ diffusion upon cycling. When adopted as binder-free electrode in half-cells, the optimized hybrid rGO/Si film delivers high gravimetric capacity (981 mA h g-1 at 200 mA g-1 with respect to the total weight of the electrode) and exceptional cycling stability (0.057% decay per cycle over 1000 cycles at 1000 mA g-1). Besides, the binder-free rGO/Si film anode is further combined with a commercial LiCoO2 foil cathode for completely flexible full cell/battery, which exhibits excellent cycling performance and a high capacity retention of over 95% after 30 cycles under continuous bending. This solution-processable, elaborately engineered, and robust Si/graphene films will further harness the potential of silicon-carbon composites for advanced flexible/wearable energy storage.