MOF-derived molybdenum selenide on Ti_(3)C_(2)T_(x) with superior capacitive performance for lithium-ion capacitors

Two-dimensional Ti_(3)C_(2)T_(x) exhibits outstanding rate property and cycle performance in lithium-ion capacitors(LICs)due to its unique layered structure,excellent electronic conductivity,and high specific surface area.However,like graphene,Ti_(3)C_(2)T_(x) restacks during electrochemical cycling due to hydrogen bonding or van der Waals forces,leading to a decrease in the specific surface area and an increase in the diffusion distance of electrolyte ions between the interlayer of the material.Here,a transition metal selenide MoSe_(2) with a special three-stacked atomic layered structure,derived from metal-organic framework(MOF),is introduced into the Ti_(3)C_(2)T_(x) structure through a solvo-thermal method.The synergic effects of rapid Li+diffusion and pillaring effect from the MoSe_(2) and excellent conductivity from the Ti_(3)C_(2)T_(x) sheets endow the material with excellent electrochemical reaction kinetics and capacity.The composite Ti_(3)C_(2)T_(x)@MoSe_(2) material exhibits a high capacity over 300 mAh·g^(-1) at 150 mA·g^(-1) and excellent rate property with a specific capacity of 150 mAh·g^(-1) at 1500 mA·g^(-1).Addition-ally,the material shows a superior capacitive contribution of 86.0%at 2.0 mV·s^(-1) due to the fast electrochemical reactions.A Ti_(3)C_(2)T_(x)@MoSe_(2)//AC LIC device is also fabricated and exhibits stable cycle performance.

Spray pyrolysis-derived W-doped MoSe_(2)/rGO paper-like microspheres:optimization of microstructure and mesostructure for enhanced lithium storage

Two-dimensional MoSe_(2) is a promising candidate for lithium-ion battery anodes.However,its conductivity and lithium storage volumetric effect still need to be optimized.In this work,W-doped MoSe_(2)/rGO paper-like microspheres are successfully prepared through ultrasonic spray pyrolysis,achieving optimization at both the microstructure and mesostructure to enhance the lithium storage performance of the material.Firstly,by utilizing the similar two-dimensional structure between MoSe_(2) and rGO,self-assembly is achieved through spray pyrolysis,resulting in a well-defined van der Waals heterostructure at the interface on the microscale,enhancing the electron and ion transfer capability of the composite.Secondly,the mesoscale paper-like microsphere morphology provides additional volume expansion buffering space.Moreover,W-doping not only increases the interlayer spacing of MoSe_(2)(0.73 nm),thereby reducing the diffusion resistance of Li+,but also allow for the modulation of the energy band structure of the material.Density functional theory(DFT)calculations confirm that W-doped MoSe_(2)/rGO exhibits the narrowest bandgap(0.892 eV).Therefore,the composite demonstrates excellent lithium storage performance,maintaining a specific capacity of 732.9 mAh·g^(-1)after 300 cycles at a current density of 1 A·g^(-1).

Facile one-step hydrothermal route to MSe/Mo_(3)Se_(4)(M:Zn,Mn,and Ni)-based electrode materials for ultralong-life hybrid supercapacitors

Transition metal selenides have attracted great interest in electrochemical energy storage applications because of their good electrochemical activity and conductivity properties.Herein,we reported the metal molybdenum selenide(M Se/Mo_(3)Se_(4)(M:Zn,Mn,and Ni))electrode materials on their morphological and electrochemical properties by varying the metal ions via a facile hydrothermal technique.The effects of the structural,morphological,and surface area properties of the prepared powder materials on their electrochemical performance were studied.Owing to the hierarchical porous and unique interconnected structure,the nickel molybdenum selenide nanosheet spheres(NMS NSSs)-based electrode material delivered an excellent specific capacity value of 252 mAh g^(-1) at a current density of 1 Ag^(-1).Moreover,the optimized NMS NSSs electrode exhibited outstanding cycling stability with a capacity retention of 80%and a corresponding coulombic efficiency of 99%after 80,000 cycles.Additionally,a pouch-type hybrid supercapacitor(HSC)device was assembled using NMS NSSs material as a positive electrode and activated carbon as a negative electrode in 1 M aqueous KOH electrolyte.Furthermore,the assembled HSC device exhibited superior energy and power density values as well as magnificent cycling stability.For real-time practical applications,light-emitting diodes and a digital display were powered using two series-connected HSC devices.Therefore,the obtained tremendous results strongly suggest that the NiSe/Mo_(3)Se_(4) NSSs-based materials could be a promising electrode for ultralong-life energy storage applications.

One-pot synthesis of MoSe2 hetero-dimensional hybrid self-assembled by nanodots and nanosheets for electrocatalytic hydrogen evolution and photothermal therapy

We designed and prepared a hetero-dimensional hybrid （HDH） based on molybdenum selenide （MoSe2） nanodots （NDs） anchored in few-layer MoSe2 nanosheets （NSs） （MoSe2 HDH） via a one-pot hydrothermal process. The MoSe2 HDH exhibits excellent electrocatalytic activity toward hydrogen evolution reaction （HER）. This is because, on the one hand, the edge-abundant features of MoSe2 NDs and the unique defect-rich structure at the interface of MoSe2 NSs/NDs could bring in more active sites for HER; on the other hand, the random stacking of the flake-like MoSe2 NSs on the surface of the supporting electrode may achieve efficient charge transport. Additionally, the MoSe2 HDH shows good water stability, desirable biocompatibility, and high near infrared （NIR） photothermal conversion efficiency. Therefore, the MoSe2 HDH is investigated as a nanomedicine in NIR photothermal therapy （PTT） for cancer. Specifically, the MoSe2 HDH can be applied as a dual-modal probe for computed tomography （CT） and photoacoustic tomography （PA） imaging owing to its strong X-ray attenuation ability and NIR absorption. Therefore, the MoSe2 HDH, combining PTT with CT/PA imaging into one system, holds great potential for imaging-guided cancer theranostics. This work may provide an ingenious strategy to prepare other hetero-dimensional layered transition metal dichalcogenides.