Engineering of Two-dimensional Cobalt-Glycine Complex Thin Sheets of Vertically Aligned Nanosheet Basic Building Blocks for High Performance Supercapacitor Electrode Materials

Novel Two-Dimensional Porous Materials for Electrochemical Energy Storage: A Minireview

Two dimensional (2D) porous materials have great potential in electrochemical energy conversion and storage. Over the past five years, our research group has focused on Simple, Mass, Homogeneous and Repeatable Synthesis of various 2D porous materials and their applications for electrochemical energy storage especially for supercapacitors (SCs). During the experimental process, through precisely controlling the experimental parameters, such as reaction species, molar ratio of different ions, concentration, pH value of reaction solution, heating temperature, and reaction time, we have successfully achieved the control of crystal structure, composition, crystallinity, morphology, and size of these 2D porous materials including transition metal oxides (TMOs), transition metal hydroxides (TMHOs), transition metal oxalates (TMOXs), transition metal coordination complexes (TMCCs) and carbon materials, as well as their derivatives and composites. We have also named some of them with CQU-Chen (CQU is the initialism of Chongqing University, Chen is the last name of Lingyun Chen), such as CQU-Chen-Co-O-1, CQU-Chen-Ni-O-H-1, CQU-Chen-Zn-Co-O-1, CQU-Chen-Zn-Co-O-2, CQU-Chen-OA-Co-2-1, CQU-Chen-Co-OA-1, CQU-Chen-Ni-OA-1, CQU-Chen-Gly-Co-3-1, CQU-Chen-Gly-Ni-2-1, CQU-Chen-Gly-Co-Ni-1, etc. The introduction of 2D porous materials as electrode materials for SCs improves the energy storage performances. These materials provide a large number of active sites for ion adsorption, supply plentiful channels for fast ion transport and boost electrical conductivity and facilitate electron transportation and ion penetration. The unique 2D porous structures review is mainly devoted to the introduction of our contribution in the 2D porous nanostructured materials for SC. Finally, the further directions about the preparation of 2D porous materials and electrochemical energy conversion and storage applications are also included.

Two-dimensional porous nickel oxalate thin sheets constructed by ultrathin nanosheets as electrode materials for high-performance aqueous supercapacitors

2D porous nickel oxalate thin sheets constructed by ultrathin nanosheets were first synthesized by using a simple hydrothermal method. The resulting porous thin sheets exhibited superior supercapacitor performance.

Needle grass-like cobalt hydrogen phosphate on Ni foam as an effective and stable electrocatalyst for the oxygen evolution reaction

Novel three dimensional needle grass-like CoHPO₄·H₂O on Ni foam has been prepared as an effective and robust OER electrocatalyst.

Size and crystallinity control of two-dimensional porous cobalt oxalate thin sheets: tuning surface structure with enhanced performance for aqueous asymmetric supercapacitors

Porous cobalt oxalate thin sheets with enhanced performance were synthesized under hydrothermal condition.

Supercapacitor and photocatalytic performances of hydrothermally-derived Co3O4/CoO@carbon nanocomposite

Hydrothermally-derived Co₃O₄/CoO@carbon nanocomposite with spike-like cobalt oxide anchored on the conductive carbon network showed excellent supercapacitor and photocatalytic performances.

High-performance supercapacitors of Cu-based porous coordination polymer nanowires and the derived porous CuO nanotubes

Electrode materials for supercapacitors with one-dimensional porous nanostructures, such as nanowires and nanotubes, are very attractive for high-efficiency storage of electrochemical energy. Herein, ultralong Cu-based porous coordination polymer nanowires (copper-l-aspartic acid) were used as the electrode material for supercapacitors, for the first time. The as-prepared material exhibits a high specific capacitance of 367 F g^-1 at 0.6 A g^-1 and excellent cycling stability (94% retention over 1000 cycles). Moreover, porous CuO nanotubes were successfully fabricated by the thermal decomposition of this nanowire precursor. The CuO nanotube exhibits good electrochemical performance with high rate capacity (77% retention at 12.5 A g^-1) and long-term stability (96% retention over 1000 cycles). The strategy developed here for the synthesis of porous nanowires and nanotubes can be extended to the construction of other electrode materials for more efficient energy storage.

Honeycomb-Like Interconnected Network of Nickel Phosphide Heteronanoparticles with Superior Electrochemical Performance for Supercapacitors

Transition-metal-based heteronanoparticles are attracting extensive attention in electrode material design for supercapacitors owing to their large surface-to-volume ratios and inherent synergies of individual components; however, they still suffer from limited interior capacity and cycling stability due to simple geometric configurations, low electrochemical activity of the surface, and poor structural integrity. Developing an elaborate architecture that endows a larger surface area, high conductivity, and mechanically robust structure is a pressing need to tackle the existing challenges of electrode materials. This work presents a supercapacitor electrode consisting of honeycomb-like biphasic Ni₅P₄-Ni₂P (Ni_xP_y) nanosheets, which are interleaved by large quantities of nanoparticles. The optimized Ni_xP_y delivers an ultrahigh specific capacity of 1272 C g^-1 at a current density of 2 A g^-1, high rate capability, and stability. An asymmetric supercapacitor employing as-synthesized Ni_xP_y as the positive electrode and activated carbon as the negative electrode exhibits significantly high power and energy densities (67.2 W h kg^-1 at 0.75 kW kg^-1; 20.4 W h kg^-1 at 15 kW kg^-1). These results demonstrate that the novel nanostructured Ni_xP_y can be potentially applied in high-performance supercapacitors.