Flower-like Ni0·85Se nanosheets with enhanced performance toward hybrid supercapacitor

Carbon Dot Regulating NiSe/MnO2 Heterostructures for High-Performance Supercapacitors

Structural regulation is an effective strategy for enhancing an electrode's energy storage performance. Herein, lignin-derived carbon dots (LCDs) are explored for the structural tailoring of NiSe/MnO2 to improve the electrochemical performance in supercapacitors. After the dendritic NiSe microcrystals are synthesized via a microwave method, NF/NiSe/MnO2-LCDs are prepared by another microwave process to form a composite mixture of LCDs, MnO2, and NF/NiSe. At 1 A g-1, NF/NiSe/MnO2-LCDs possess a specific capacitance of 2268 F g-1 and superb lifespans (84.43%, 3000 cycles) for their enhanced ion transport and rapid electron transfer. In addition, the NF/NiSe/MnO2-LCDs//AC ASC showed an energy density of 51.62 Wh kg-1 at 800 W kg-1 and extraordinary endurance with 88.46% retention (7000 loops). The NF/NiSe/MnO2-LCDs offer ideas to improve the capacity retention and storage capacity of electrodes for supercapacitors.

Coupling MoSe2 with Non-Stoichiometry Ni0.85 Se in Carbon Hollow Nanoflowers for Efficient Electrocatalytic Synergistic Effect on Li-O2 Batteries

Li-O2 batteries could deliver ultra-high theoretical energy density compared to current Li-ion batteries counterpart. The slow cathode reaction kinetics in Li-O2 batteries, however, limits their electrocatalytic performance. To this end, MoSe2 and Ni0.85 Se nanoflakes were decorated in carbon hollow nanoflowers, which were served as the cathode catalysts for Li-O2 batteries. The hexagonal Ni0.85 Se and MoSe2 show good structural compatibility with the same space group, resulting in a stable heterogeneous structure. The synergistic interaction of the unsaturated atoms and the built-in electric fields on the heterogeneous structure exposes abundant catalytically active sites, accelerating ion and charge transport and imparting superior electrochemical activity, including high specific capacities and stable cycling performance. More importantly, the lattice distances of the Ni0.85 Se (101) plane and MoSe2 (100) plane at the heterogeneous interfaces are highly matched to that of Li2 O2 (100) plane, facilitating epitaxial growth of Li2 O2 , as well as the formation and decomposition of discharge products during the cycles. This strategy of employing nonstoichiometric compounds to build heterojunctions and improve Li-O2 battery performance is expected to be applied to other energy storage or conversion systems.

Facile One-Step Microwave-Assisted Method to Synthesize Nickel Selenide Nanosheets for High-Performance Hybrid Supercapacitor

Nanosheets structures can be employed as the most promising electrode material to enhance electrochemical performance for supercapacitors. Nickel Selenide (Ni_0.85Se) nanosheets are synthesized using a rapid microwave synthesis method in a single step. The Ni_0.85Se nanosheets possess a high surface area (125 m²g^-1) with a hexagonal crystalline structure. It shows magnificent electrochemical properties, such as splendid specific capacitance (2530 Fg^-1 at 0.5 Ag^-1). An asymmetric hybrid supercapacitor is fabricated with nickel selenide nanosheets as a positive electrode and activated carbon as a negative electrode. The assembled hybrid supercapacitor displays a high energy density of 63.5 WhKg^-1 at a power density of 404 WKg^-1, and after 8000 cycles, only 5% capacitance is lost along with the better voltage window at 0-1.6 V.

Regulation of Morphology and Electrochemical Properties of Ni0.85Se via Fe Doping for Overall Water Splitting and Supercapacitor

The Fe-doped Ni0.85Se nanosheets array on Ni foam was synthesized successfully through one-step solvothermal method as effective binder-free multifunctional catalysts for hydrogen evolution reaction (HER), oxygen evolution reaction (OER), overall...

A facile synthesis of Ni0.85Se@Cu2-xSe nanorods as high-performance supercapacitor electrode materials

Transition-metal selenides are regarded as promising electrode materials due to their superior electrochemical performances for supercapacitors. In this study, a nanorod-like hybrid of Ni_0.85Se@Cu_2-xSe on a Ni-foam substrate is successfully synthesized via a facile one-step route. The Ni_0.85Se@Cu_2-xSe nanorods are found to be deposited uniformly on the Ni-form substrates. When used as a battery-type electrode in a supercapacitor, the as-deposited Ni_0.85Se@Cu_2-xSe electrode exhibits a high specific capacity of 1831 F g^-1 at 1 A g^-1 and 78.4% of capacitance retention after 8000 cycles at 10 A g^-1. Moreover, the assembled Ni_0.85Se@Cu_2-xSe//AC asymmetric supercapacitor (ASC) exhibits an energy density of 63.2 W h kg^-1 at a power density of 800.1 W kg^-1, as well as good cycling stability (92.1% capacitance retention after 5000 cycles).

Recent progress in transition metal selenide electrocatalysts for water splitting

The urgent demand of scalable hydrogen production has motivated substantial research on low cost, efficient and robust catalysts for water electrolysis. In order to replace noble metals and their derivatives, transition metal (Fe, Co, Ni, Mo, Cu, etc.) selenides have demonstrated promising catalysis on both hydrogen and oxygen evolutions. Very recently, a number of reports have presented a variety of approaches to enhance their electrocatalytic activity. This review summarizes the most recent progress in transition metal selenide electrocatalysts for HER, OER, and overall water splitting. The merits and limitations of metal selenides are also discussed in the aspects of structure and composition. Moreover, we highlight new strategies and future challenges for design and synthesis of high performance electrocatalysts.

Construction of a bimetallic nickel–cobalt selenide pompon used as a superior anode material for high performance sodium storage

Pompon-like NiCo₂Se₄ can effectively promote the penetration of an electrolyte, increase electron and ion diffusion channels, alleviate volume expansion and achieve excellent sodium storage performance.