Bottom-up Approach for Designing Cobalt Tungstate Nanospheres through Sulfur Amendment for High-Performance Hybrid Supercapacitors

Optimizing Energy Solutions: Mott-Schottky Engineered 1D/3D CoWO4(OH)2·H2O/MoS2 Heterostructure for Advanced Energy Storage and Conversion Application

Heterostructure engineering offers a powerful approach to creating innovative electrocatalysts. By combining different materials, it can achieve synergistic effects that enhance both charge storage and electrocatalytic activity. In this work, it is capitalized on this concept by designing a 1D/3D CoWO4(OH)2·H2O/molybdenum disulfide (CTH/MoS2) heterostructure. It is achieved this by in situ depositing 3D MoS2 nanoflowers on 1D CTH nanorods. To explore the impact of precursor choice, various sulfur (S) sources is investigated. Interestingly, the S precursor influenced the dimensionality of the MoS2 component. For example, L-cysteine (L-cys), and glutathione (GSH) resulted in 0D morphologies, thiourea (TU) led to a 2D structure, and thioacetamide (TAA) yielded a desirable 3D architecture. Notably, the 1D/3D CTH/MoS2-TAA heterostructure exhibited exceptional performance in both supercapacitors (SCs) and quantum dot-sensitized solar cells (QDSSCs). This achievement can be attributed to several factors: the synergetic effect between 1D CTH and 3D MoS2, improved accessibility due to the multi-dimensional structure, and a tailored electronic structure facilitated by the Mott-Schottky (M-S) interaction arising from the different material Fermi levels. This interaction further enhances conductivity, ultimately leading to the observed high specific capacity in SCs (154.44 mAh g-1 at 3 mA cm-2) and remarkable photovoltaic efficiency in QDSSCs (6.48%).

Zn-BTC MOF as Self-Template to Hierarchical ZnS/NiS2 Heterostructure with Improved Electrochemical Performance for Hybrid Supercapacitor

Zn-BTC (H3BTC refers to 1, 3, 5-benzoic acid) MOF was used as a self-template and a zinc source to prepare ZnS/NiS2 with a layered heterogeneous structure as a promising electrode material using cation exchange and solid-phase vulcanization processes. The synergistic effect of the two metal sulfides enhances the application of ZnS/NiS2. And the high specific surface area and abundant active sites further promote the mass/charge transfer and redox reaction kinetics. In the three-electrode system, the specific capacitance was as high as 1547 F/g at a current density of 1 A/g, along with satisfactory rate capability (1214 F/g at 6 A/g) and cycling performance. Coupled with activated carbon (AC), the prepared hybrid device (ZnS/NiS2 as the positive electrode and AC as the negative electrode) (ZnS/NiS2/AC) can be operated under a potential window of 1.6 V and provides a high energy density of 26.3 Wh/kg at a power density of 794 W/kg. Notably, the assembled ZnS/NiS2//AC showed little capacity degradation after 5000 charge/discharge cycles.

Synthesis of active-site rich molybdenum-doped manganese tungstate nanocubes for effective electrochemical sensing of the antiviral drug (COVID-19) nitazoxanide

Nitazoxanide (NTZ), a promising antiviral agent, is currently being tested in clinical trials as a potential treatment for novel coronavirus disease 2019 (COVID -19). This paper describes a one-pot hydrothermal synthesis to prepare molybdenum (Mo)-doped manganese tungstate nanocubes (Mo-MnWO4 NCs) for the electrochemical sensing of NTZ. The as-prepared Mo-MnWO4 NCs were characterized using various techniques such as XRD, Raman, FE-SEM, FE-TEM, and XPS to confirm the crystal structure, morphology, and elemental composition. The obtained results demonstrate that Mo doping on MnWO4 generates many vacancy sites, exhibiting remarkable electrochemical activity. The kinetic parameters of the electrode modified with Mo-MnWO4 NCs were calculated to be (Ks) 1.1 × 10-2 cm2 s-1 and (α) 0.97, respectively. Moreover, a novel electrochemical sensor using Mo-MnWO4 NCs was fabricated to detect NTZ, which is used as a primary antibiotic to control COVID-19. Under optimal conditions, the electrochemical reduction of NTZ was determined with a low detection limit of 3.7 nM for a linear range of 0.014-170.2 μM with a high sensitivity of 0.78 μA μM-1 cm-2 and negligible interference with other nitro group-containing drugs, cations, and anions. The electrochemical sensor was successfully used to detect NTZ in the blood serum and urine samples and achieved high recoveries in the range of 94-99.2% and 95.3-99.6%, respectively. This work opens a way to develop high-performance sensing materials by exploring the introduction of defect engineering on metal tungstates to detect drug molecules for practical applications.

Unique CoWO4@WO3 heterostructured nanosheets with superior electrochemical performances for all-solid-state supercapacitors

Transition metal oxide-based battery-type electrode materials with well-defined nanostructure have shown great potential in supercapacitors, due to their high electrical conductivity and superior redox activity. Herein, promising CoWO₄@WO₃-1 heterostructured nanosheets with rich oxygen vacancies are designed via a two-step in situ construction process and following thermal treatment. The CoWO₄@WO₃-1 heterostructured nanosheet arrays grown on a flexible carbon cloth substrate can provide an effective nanoporous framework, facilitate electrons/ions transport, and generate effective synergistic effect of high conductivity from WO₃ and superior redox activity from CoWO₄. As a result, the as-prepared CoWO₄@WO₃-1 electrodes exhibit a high area specific capacity of 578.6 mF cm^-2 at a current density of 0.5 mA cm^-2 and keep 98.38% capacity retention at 20 mA cm^-2 over 30 000 cycles. Additionally, all-solid-state supercapacitors assembled with CoWO₄@WO₃-1 as cathodes and O_v-NiMoO₄ as anodes show a maximum area energy density of 13.93 mW h cm^-2 and power density of 6502.11 mW cm^-2, keeping outstanding cycling stability of 98.1% capacity retention over 20 000 cycles.

Construction of Macroporous Co2SnO4 with Hollow Skeletons as Anodes for Lithium-Ion Batteries

Increasing the energy density of lithium-ion batteries (LIBs) can broaden their applications in energy storage but remains a formidable challenge. Herein, with polyacrylic acid (PAA) as phase separation agent, macroporous Co₂SnO₄ with hollow skeletons was prepared by sol-gel method combined with phase separation. As the anode of LIBs, the macroporous Co₂SnO₄ demonstrates high capacity retention (115.5% at 200 mA·g⁻¹ after 300 cycles), affording an ultrahigh specific capacity (921.8 mA h·g⁻¹ at 1 A·g⁻¹). The present contribution provides insight into engineering porous tin-based materials for energy storage.

Preparation of N/O co-doped porous carbon by a one-step activation method for supercapacitor electrode materials

Heteroatom-doped carbon materials used in supercapacitors are low in cost and demonstrate extraordinary performance. Here, ethylenediamine tetraacetic acid (EDTA) with intrinsic N and O elements is selected as a raw material for the preparation of heteroatom self-doped porous carbon. Furthermore, N/O self-doped porous carbon with a large surface area has been successfully prepared using K₂CO₃ as the activator. The derived sample with a 1 : 2 molar ratio of EDTA to K₂CO₃ (EK-2) demonstrates a porous structure, rich defects, a large surface area of 2057 m² g⁻¹ and a micropore volume of 0.25 cm³ g⁻¹. Benefiting from high N content (2.89 at%) and O content (10.75 at%), EK-2 exhibits superior performance, including high capacitance of 325 F g⁻¹ at 1 A g⁻¹ and outstanding cycling stability with 96.8% retention after 8000 cycles at 10 A g⁻¹, which strongly confirms its immense potential toward many applications. Additionally, the maximum energy density of EK-2 reaches was 17.01 W h kg⁻¹ at a power density of 350 W kg⁻¹ in a two-electrode system. This facile and versatile strategy provides a scalable approach for the batch synthesis of N/O co-doped carbonaceous electrode materials for energy storage.

Heteroatom-doped carbon materials used in supercapacitors are low in cost and demonstrate extraordinary performance.