Sea urchin-like CoNi2S4materials derived from nickel hexamyanocobaltate for high-performance asymmetric hybrid supercapacitor.

In this work, a mild chemical precipitation method and simple hydrothermal treatment of the nickel hexamyanocobaltate precursor strategy are developed to prepare a sea urchin-like CoNi2S4compound with remarkable specific capacity and excellent cycling stability. The prepared CoNi2S4has an outstanding specific capacity of 149.1 mA h g-1at 1 A g-1and an initial capacity of 83.1% after 3000 cycles at 10 A g-1. Moreover, the porous carbon nanospheres (PCNs) with exhibit cycling stability (94.7% of initial specific capacity after 10 000 cycles at 10 A g-1) are selected as negative electrode to match CoNi2S4positive electrode for assembly of CoNi2S4//PCNs asymmetric supercapacitor (ASC). Satisfactorily, the as-assembled CoNi2S4//PCNs ASC exhibits an impressive energy density of 41.6 Wh kg-1at 797 W kg-1, as well as the suitable capacity retention of 82.8% after 10 000 cycles. The superior properties of the device demonstrated that the as-prepared material is potential energy storage material.

Fabrication of a 3D Hierarchical Sandwich Co9 S8 /α-MnS@N-C@MoS2 Nanowire Architectures as Advanced Electrode Material for High Performance Hybrid Supercapacitors.

Supercapacitors suffer from lack of energy density and impulse the energy density limit, so a new class of hybrid electrode materials with promising architectures is strongly desirable. Here, the rational design of a 3D hierarchical sandwich Co9 S8 /α-MnS@N-C@MoS2 nanowire architecture is achieved during the hydrothermal sulphurization reaction by the conversion of binary mesoporous metal oxide core to corresponding individual metal sulphides core along with the formation of outer metal sulphide shell at the same time. Benefiting from the 3D hierarchical sandwich architecture, Co9 S8 /α-MnS@N-C@MoS2 electrode exhibits enhanced electrochemical performance with high specific capacity/capacitance of 306 mA h g-1 /1938 F g-1 at 1 A g-1 , and excellent cycling stability with a specific capacity retention of 86.9% after 10 000 cycles at 10 A g-1 . Moreover, the fabricated asymmetric supercapacitor device using Co9 S8 /α-MnS@N-C@MoS2 as the positive electrode and nitrogen doped graphene as the negative electrode demonstrates high energy density of 64.2 Wh kg-1 at 729.2 W kg-1 , and a promising energy density of 23.5 Wh kg-1 is still attained at a high power density of 11 300 W kg-1 . The hybrid electrode with 3D hierarchical sandwich architecture promotes enhanced energy density with excellent cyclic stability for energy storage.

Mo-doping and construction of the heterostructure between NiFe LDH and NiSx co-trigger the activity enhancement for overall water splitting.

To reduce the preparation cost of high-purity hydrogen, it is necessary to search suitable non-precious metal catalysts with high activity and robust stability. Herein, two means (heteroatom-doping and the heterostructure construction) were adopted together to improve the dual-function activity of NiFe LDH which was widely used in water electrolysis. Mo doped NiFe LDH nanoflowers were firstly generated by hydrothermal reaction, and then NiSx was modified on the petals via electrodeposition. Finally, the obtained NF/Mo-NiFe LDH/NiSx with large electrochemical active area exhibits the expected electrochemical performance with the overpotential at 100 mA cm-2 of 169 and 249 mV for hydrogen evolution (HER) and oxygen evolution reaction (OER) respectively. Assembling NF/Mo-NiFe LDH/NiSx into a two-electrode device for the integral water electrolysis, it just requires a cell voltage of 1.69 V to drive a current density of 100 mA cm-2, and keeps stable after 50-hour continuous operation in 1.0 M KOH. Mo-doping not only regulates the electronic structure of the transition metals and reduces the energy barrier of HER intermediates, but also facilitates the generation of reactive sites for OER. Meanwhile, the construction of heterointerface ensures the synergism between NiSx and Mo-NiFe LDH and accelerates the electron transfer across interfaces, thus enhancing the bifunctional performance.

Recent Advancements in Ascribing Several Platinum Free Electrocatalysts Pertinent to Hydrogen Evolution from Water Reduction.

The advancement of a sustainable and scalable catalyst for hydrogen production is crucial for the future of the hydrogen economy. Electrochemical water splitting stands out as a promising pathway for sustainable hydrogen production. However, the development of Pt-free electrocatalysts that match the energy efficiency of Pt while remaining economical poses a significant challenge. This review addresses this challenge by highlighting latest breakthroughs in Pt-free catalysts for the hydrogen evolution reaction (HER). Specifically, we delve into the catalytic performance of various transition metal phosphides, metal carbides, metal sulphides, and metal nitrides toward HER. Our discussion emphasizes strategies for enhancing catalytic performance and explores the relationship between structural composition and the performance of different electrocatalysts. Through this comprehensive review, we aim to provide insights into the ongoing efforts to overcome barriers to scalable hydrogen production and pave the way for a sustainable hydrogen economy.

Current Trends and Promising Electrode Materials in Micro-Supercapacitor Printing.

The development of scientific and technological foundations for the creation of high-performance energy storage devices is becoming increasingly important due to the rapid development of microelectronics, including flexible and wearable microelectronics. Supercapacitors are indispensable devices for the power supply of systems requiring high power, high charging-discharging rates, cyclic stability, and long service life and a wide range of operating temperatures (from -40 to 70 °C). The use of printing technologies gives an opportunity to move the production of such devices to a new level due to the possibility of the automated formation of micro-supercapacitors (including flexible, stretchable, wearable) with the required type of geometric implementation, to reduce time and labour costs for their creation, and to expand the prospects of their commercialization and widespread use. Within the framework of this review, we have focused on the consideration of the key commonly used supercapacitor electrode materials and highlighted examples of their successful printing in the process of assembling miniature energy storage devices.

Vertical 2-dimensional heterostructure SnS-SnS2 with built-in electric field on rGO to accelerate charge transfer and improve the shuttle effect of polysulfides.

Traditional carbon materials as sulfur hosts of Li-sulfur(Li-S) cathodes have slightly physical constraint for polysulfides, due to their no-polar property. Therefore, it is necessary to further enhance the affinity between sulfur hosts and polysulfides, and relieve the shuttle effects in the Li- S batteries. Herein, we report a novel vertical 2-dimensional (2D) p-SnS/n-SnS2 heterostructure sheets which grown on the surface of rGO. The excellent electrochemical properties of SnS-SnS2@rGO as Li-S cathode are ascribed to the stronger absorption effect of metal sulphides for polysulfides and the smooth trapping-diffusion-conversion effect of p-SnS/n-SnS2 heterostructure for polysulfides. As a conductive carrier for the growth of vertical 2D p-SnS/n-SnS2 heterostructure nanosheets, rGO can protect the steadiness and enhance the cycle stability of electrode, compared with heterostructure without rGO. In addition, the built-in electric field in the 2D p-SnS/n-SnS2 heterostructure during the discharge/charge processes can effectively accelerate charge transfer, and the charge transfer mechanism in SnS-SnS2 heterostructure during cycling has been investigated. At a rate capability of 2C, the designed SnS-SnS2@rGO as Li-S cathode delivers high specific capacities of 907 mAh g-1 and 571 mAh g-1 after the first cycle and 500 cycles, respectively, which shown excellent cycling ability.

Metal Sulphides and Their Carbon Supported Composites as Platinum-Free Counter Electrodes in Dye-Sensitized Solar Cells: A Review.

Energy sufficiency is a critical requirement for the economic prosperity of modern countries. Efficient harnessing of solar energy using technologies such as the dye-sensitized solar cell could solve the energy problem which persistently plagues developing countries. Despite having a simple operational procedure and modest power conversion efficiency of 13.8%, the dye-sensitized solar cell consists of an expensive platinum counter electrode which makes commercial success futile. Thus, this review intends to establish the progress researchers have attained in the development of sulphide based counter electrodes as alternatives to platinum, thereby lowering cost of production. Metallic sulphides are good electrocatalysts and cheap, hence, they possess the necessary requirements for effective functional counter electrodes. Furthermore, ternary metallic sulphides are known to exhibit higher efficiencies stemming from the synergistic effect produced by the co-existence of two metal ions in a crystal structure, which is believed to induce greater catalytic capability. Incorporation of metallic sulphides with carbon materials, which are exceptional electrical conductors, could potentially produce more efficient counter electrodes. In that regard, this review seeks to establish the effect recently developed composite counter electrodes comprising metallic sulphides and carbon-based materials have induced on the functionality of the counter electrode (CE).