Unique hollow-concave CoMoSx boxes with abundant mesoporous structure for high-performance hybrid supercapacitors

High-Performance Mo-CoS2 Nanoplates Derived from Metal-Organic Frameworks for Asymmetric Supercapacitor Applications

As global energy and environmental challenges intensify, advancing renewable energy storage technologies is critical. Supercapacitors, known for their rapid charge-discharge rates and exceptional cycling stability, are a promising solution; however, they are constrained by their comparatively low energy density. This study addresses this limitation by developing high-performance Mo-CoS2 nanoplates derived from metal-organic frameworks for asymmetric supercapacitor applications. Using ZIF-67 nanoplates as precursors, Mo-CoS2 hybrids were synthesized through a two-step process that included carbonization followed by sulfurization. The Mo-CoS2 hybrids maintained its plate-like morphology with plentiful active sites, which are crucial for superior electrochemical performance. The Mo-CoS2 electrode delivers a specific capacitance of 1382.6 F g-1 at 0.5 A g-1, significantly surpassing that of CoS2 and MoS2 alone. An asymmetric supercapacitor incorporating Mo-CoS2 and ZIF-67-derived carbon electrodes demonstrate a remarkable energy density of 49.4 Wh kg-1 at a power density of 703 W kg-1, while retaining 72.09% of their initial performance after 10 000 cycles. The findings underscore the potential of materials derived from metal-organic frameworks (MOFs) in enhancing supercapacitor technology, as they offer a combination of high capacitance and long-term stability.

Hierarchical Cube-in-Cube Cobalt-Molybdenum Phosphide Hollow Nanoboxes Derived from the MOF Template Strategy for High-Performance Supercapacitors

The design of hierarchical hollow nanostructures with complex shell architectures is an attractive and effective way to obtain a desirable electrode material for energy storage application. Herein, we report an effective metal-organic framework (MOF) template-engaged method to synthesize novel double-shelled hollow nanoboxes, in terms of chemical composition and structure complexity, for supercapacitor application. Starting from cobalt-based zeolitic imidazolate framework (ZIF-67(Co)) nanoboxes as the removal template, we developed a rational preparation approach to synthesize cobalt-molybdenum-phosphide (CoMoP) double-shelled hollow nanoboxes (donated as CoMoP-DSHNBs) through (i) ion-exchange reaction, (ii) template etching, and (iii) phosphorization treatment, respectively. Notably, despite the previously reported works, the phosphorization was simply done using the facile solvothermal method, without employing annealing and high-temperature conditions, which can be considered as one of the merits of the current work. CoMoP-DSHNBs showed excellent electrochemical properties owing to their unique morphology, high surface area, and optimal elemental composition. In a three-electrode system, the target material showed a superior specific capacity of 1204 F g^-1 at 1 A g^-1 with a remarkable cycle stability of 87% after 20000 cycles. The hybrid device formed of activated carbon (AC) as the negative electrode and CoMoP-DSHNBs as the positive electrode exhibited a high specific energy density of 49.99 W h kg^-1 and a maximum power density of 7539.41 W kg^-1 with a great cycling stability of 84.5% after 20,000 cycles.

Achieving Ultrahigh Energy-Density Aqueous Supercapacitors via a Novel Acidic Radical Adsorption Capacity-Activation Mechanism in Ni(SeO3 )/Metal Sulfide Heterostructure

Transitional metal chalcogenide (TMC) is considered as one promising high-capacity electrode material for asymmetric supercapacitors. More evidence indicates that TMCs have the same charge storage mechanism as hydroxides, but the reason why TMC electrode materials always provide higher capacity is rare to insight. In this work, a Ni_x Co_y Mn_z S/Ni(SeO₃ ) (NCMS/NSeO) heterostructure is prepared on Ni-plated carbon cloth, validating that both NCMS and NSeO can be transformed into hydroxides in electrochemical process as accompanying with the formation of SeO₃ ^2- and SO_x ^2- in confined spaces of NCMS/NSeO/Ni sandwich structure. Based on density functional theory calculation and experimental results, a novel space-confined acidic radical adsorption capacity-activation mechanism is proposed for the first time, which can nicely explain the capacity enhancement of NCMS/NSeO electrode materials. Thanks to the unique capacity enhancement mechanism and stable NCMS/NSeO/Ni sandwich structure, the optimized electrodes exhibit a high capacity of 536 mAh g^-1 at 1 A g^-1 and the impressive rate capability of 140.5 mAh g^-1 at the amazing current density of 200 A g^-1 . The assembled asymmetric supercapacitor achieves an ultrahigh energy density of 141 Wh Kg^-1 and an impressive high-rate capability and cyclability combination with 124% capacitance retention after 10 000 cycles at a large current density of 50 A g^-1 .