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A novel strategy is proposed through the in-situ growth of one-dimensional H-VOOH nanorod arrays on flexible conducting substrates as ZIBs cathode material. The synergistic effect between the hollandite-type tunnel structure and the functional group-modified conductive collector, not only accelerates the charge transfer rate and increases zinc ion intercalation capacity but also enhances the structural stability of the electrode by improving the interface stability and alleviating the detachment between the active material and the collector during the charge/discharge process. Benefitting from these merits, as-prepared H-VOOH@CF achieves high reversible capacity and ultralong cyclic stability. [Display omitted] • Novel H-VOOH was prepared by solvothermal insitu growth on conducting carbon cloth. • Hollandite-type tunnel structure accelerates the charge transfer rate. • In-situ growth improves the interface stability between the H-VOOH and the C cloth. • Such a nanostructure enhances the structural stability of the electrode. • H-VOOH@CC delivers high reversible capacity and ultralong cyclic stability. As cathodes for aqueous zinc ion batteries (ZIBs), vanadium-based materials have received a lot of attention in recent years because of their high theoretical capacities and suitable working potentials. However, the sluggish kinetics and volume expansion effects lead to their rapid capacity decay and poor rate performance. Herein, a novel strategy is proposed through the in-situ growth of one-dimensional hollandite-type VO 1.52 (OH) 0.77 nanorod arrays on flexible carbon fiber cloth as ZIBs cathode material. The synergistic effect between the hollandite-type tunnel structure and the functional group-modified conductive collector, not only accelerates the charge transfer rate and increases zinc ion intercalation capacity but also enhances the structural stability of the electrode by improving the interface stability and alleviating the detachment between the VO 1.52 (OH) 0.77 nanorod arrays and the conducting substrate during the charge/discharge process. Benefitting from these merits, as-prepared VO 1.52 (OH) 0.77 achieves an impressive reversible capacity of 305.6 mAh g−1 at 100 mA g−1 and ultralong cyclic stability (96.4% retention over 1000 cycles). This work reveals a concise approach to the construction of hollandite-type and demonstrates that the structural stability of vanadium-based oxide cathodes can be significantly enhanced by elegant structural design, thereby improving their Zn ion storage performance. [ABSTRACT FROM AUTHOR]

[Display omitted] • Nonlinear relationships between activities of Pt/CeO 2 and discharge time was found. • Pt particle size and oxygen vacancies can be regulated by controlling the discharge time. • Discharge time has a stronger impact on oxygen vacancy than Pt atom. • Pt/CeO 2 -PT5 demonstrated poor activity due to carbon deposition on the surface. This work demonstrated that a dielectric barrier discharge plasma was applied to modify the performance of catalyst. The Pt/CeO 2 catalyst was treated with various plasma discharge time to reveal the effect of plasma on the performance of Pt/CeO 2 catalyst for toluene oxidation. It is interesting that two volcanic peaks appeared at discharge time of 30 min (Pt/CeO 2 -PT3) and 3 h (Pt/CeO 2 -PT6). Compared to Pt/CeO 2 without plasma treatment, their catalytic activities (T 90) decreased by 24 °C for Pt/CeO 2 -PT3 and 34 °C for Pt/CeO 2 -PT6, respectively. By contrast, the Pt/CeO 2 -PT5 (2 h) showed the lowest activity due to the surface carbon deposition. We demonstrated that the plasma discharge time significantly affects the Pt particle size, CeO 2 -rod length, oxygen vacancies, and redox ability of the Pt/CeO 2 catalyst by using the characterizations of X-ray power diffraction patterns (XRD), specific surface area (BET), high resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS) and hydrogen temperature-programmed reduction (H 2 -TPR). The linear relationship between catalytic activities and turnover frequency values (TOF Pt and TOF Ov) were observed in the discharge time ≤1 h. Furthermore, we found that discharge time has a more profound impact on oxygen vacancy than Pt particle. [ABSTRACT FROM AUTHOR]

Selenium partially reduced Co 3 O 4 mesoporous nanowires array on carbon cloth was synthesized as high-performance and stable electrode for supercapacitors. [Display omitted] • Abundant defects in spinel Co 3 O 4 on carbon cloth are introduced by Se partially reduction. • Oxygen vacancies improve the charge storage kinetics of Co 3 O 4 @CC electrode. • The COS@CC electrode exhibits high specific capacitance up to 2039.9F g−1. • The electrode exhibits excellent capability and superior cyclic stability. The electrodes with high conductivity, large specific surface area and homogeneous pore size distribution are greatly desirable for supercapacitors applications. Herein, a hydrothermal and subsequent annealing approach was adopted to fabricate 3D interconnected nanowires architecture of selenium partially reduced spinel Co 3 O 4 grew on the carbon cloth (COS@CC). The binder-free COS@CC electrode displays excellent specific capacitance, 1046.9 C g−1 at 1 A g−1, superior rate capability, 51.6% capacitance retention and superior cyclic stability, 92.0% capacitance retention after 15,000 cycles. These electrochemical performances were found to be better than that of the Co 3 O 4 @CC electrode. The enhanced electrochemical performance was ascribed to the fact that 3D interconnected architecture nanowires could shorten the ion transfer distance and heighten the rate of the redox reaction. In addition, increased specific surface area and homogeneous mesopore size distribution could assist effective diffusion and transfer of OH– between electrodes and electrolyte. The enhancement of conductivity, which is caused by the selenium partial reduction and more oxygen vacancies in the structure, facilitates electrons transfer and consequently improves the electrochemical properties of supercapacitors. These remarkable electrochemical performances indicate that the CSO@CC can be employed for developing high-energy and power-density supercapacitors. [ABSTRACT FROM AUTHOR]

Abstract In this work, N-doped anodized stainless-steel mesh (NASSM) with mesoporous structure is demonstrated as a highly efficient, stable and bifunctional electrocatalyst with tuned electronic structure and surface morphology. NASSM was fabricated by anodic oxidation with Cr as non-catalytic substance by in situ removal of the SSM surface to regulate the morphology with mesoporous structure, followed by nitrogenization. NASSM showed an overpotential of 225 mV at 10 mA cm−2, which exceeded that of commercial IrO 2 /C catalyst, with a low Tafel slope of 49.7 mV dec−1 and excellent stability for over 100 h. NASSM exhibited an overpotential of 146 mV at 10 mA cm−2 and a Tafel slope of 60.1 mV dec−1. NASSM, as a bifunctional electrocatalyst, showed potentials of 1.61 and 1.76 V at 10 and 50 mA cm−2, respectively, for overall water-splitting with only a 0.01 V increase after a long-term stability test. These values are superior to those reported for directly modified SS-based bifunctional electrocatalysts. The remarkable catalytic properties of NASSM could be attributed to the tuning of not only electronic structure but also surface morphology. This work reports an efficient approach to synthesize and tune an effective and low-cost bifunctional catalyst based on SSM for large-scale application. Graphical abstract Unlabelled Image Highlights • Flexible NASSM were synthesized via anodic oxidation followed by nitrogenization. • NASSM shows a potential of 1.61 V at 10 mA cm−2 for overall water splitting. • NASSM's performance exceeds directly modified SS catalysts for water splitting. • Dual template effect improves catalytic performance. [ABSTRACT FROM AUTHOR]

Homogeneous nanoporous, oxygen-rich functional groups and superior performance of zinc ion hybrid supercapacitor carbon cloth cathodes were prepared by hydrothermal oxidation and in situ coating. [Display omitted] • • Porous structure on carbon cloth was prepared by a hydrothermal etching strategy. • • Modified carbon cloth-based Zn-HSC shows a high area capacity of 4.74 mAh cm2. • • The aqueous Zn-HSC device has a capacity retention of 92% after 10,000 cycles. • • Flexible Zn-HSC device provides a volume energy density of 27.22 mWh cm−3. A novel modification method of hydrothermal treatment in acidic potassium chlorate solution is proposed here to etch directly the commercial carbon cloth (CC) surface to produce a porous structure with oxygen-rich functional groups and a large specific surface area (OCC). Following that, an in-situ polypyrrole coating is deposited on OCC (PPy@OCC) to improve conductivity and electrochemical stability. The assembled zinc-ion hybrid supercapacitors (Zn-HSCs) used the PPy@OCC sample as the cathode and Zn foil as the anode, and they demonstrated excellent electrochemical properties. The device has a capacity retention of 92 % after 10,000 cycles at a current density of 20 mA cm−2 and an area capacity of up to 4.74 mAh cm−2 at a current density of 0.5 mA cm−2. It also has a high surface energy density of 4740 Wh cm−2 and a high peak surface power density of 20.23 mW cm−2. When the Zn foil is replaced as the anode to flexible Zn-HSCs by electrodeposited Zn on CC (Zn@CC), the remarkable volume energy density (27.22 mWh cm−3) and flexibility are demonstrated, implying that the prepared PPy@OCC is an ideal electrode for high-performance flexible Zn-HSCs. [ABSTRACT FROM AUTHOR]

Highlights • δ-MnO 2 nanosheets were facilely synthesized on hollow carbon nanofibers. • The MnO 2 /HCNFs nanocomposites exhibited typical mesoporous structures. • An assembled supercapacitor delivered a high energy density of 35.1 Wh kg−1. • The device showed an outstanding stability up to 10,000 GCD cycles. Abstract A novel hierarchical hollow nanostructure composed of δ-MnO 2 nanosheets deposited by in-situ growth on hollow carbon nanofibers (MnO 2 /HCNFs) was facilely synthesized using the hydrothermal method. Benefitting from its distinctive hollow structure, nanocomposite of MnO 2 /HCNFs exhibited an enhanced electrochemical property with higher specific capacitance (293.6 F g−1 at 0.5 A g−1 in 1 M Na 2 SO 4 electrolyte) compared to non-hollow structure. Further, an asymmetric supercapacitor (ASC) coin cell was assembled with the MnO 2 /HCNFs nanocomposites (positive electrode) and KOH-activated porous carbon nanofibers (PCNFs) (negative electrode). The asymmetric supercapacitor coin cell exhibited a maximum specific capacitance of 63.9 F g−1 at a high operating voltage window up to 2 V. Moreover, the ASC coin cell possessed a high energy density of 35.1 Wh kg−1 and showed a remarkable cycling stability and only 8.9% capacitance loss was found after 10,000 cycles, which implied the practicability for energy storage. [ABSTRACT FROM AUTHOR]