Zhuqing Zhang

Construction of three-dimensional CuCo2S4/CNT/graphene nanocomposite for high performance supercapacitors

The search for safe and efficient energy storage systems continues to inspire researchers to develop new energy storage materials with excellent performance. Graphene-based three-dimensional (3D) nanostructures are interesting to supercapacitors (SCs) because of their high surface area, ample number of active sites, and good conductivity. This combination of attributes allows for full utilization capacitance of active electrode materials. Herein, three-dimensional CuCo2S4–g–CNT structure was fabricated successfully with the hydrothermal method. Serving as the active electrode, CuCo2S4–g–CNT demonstrated a remarkable specific capacitance (504 F g−1 at the current density of 10 A g−1). Moreover, the as-obtained CuCo2S4–g–CNT hybrid electrode is robust, exhibiting exceptional cycle life, as revealed by galvanostatic charge–discharge studies (retaining 92.3% after 2000 cycles). Its durability is mainly due to the synergistic effects of CuCo2S4, graphene and CNTs. These unique nano-architectures demonstrate potential applications in energy storage electrodes and may indeed spur a new generation of hybrid SCs to bridge the energy gap between SCs and chemical batteries.

Cobalt-Doped FeSe2-RGO as Highly Active and Stable Electrocatalysts for Hydrogen Evolution Reactions.

Herein, we describe the preparation and testing of Co-doped FeSe2 hybridized with graphene (Fe1-xCoxSe2/RGO), a high-active yet stable electrocatalyst for hydrogen evolution reactions (HERs) in acidic solutions. First, we systematically analyze the composition and morphology of Fe1-xCoxSe2/RGO and attribute its excellent electrochemical performance to its unique architecture-a base of highly conductive graphene with fully exposed active edges that enhances conductivity and facilitates ion/electron transfer. Our experimental measurements indicate elevated HER activity with a moderate overpotential of ∼166 mV at a hydrogen production current density of 10 mA cm(-2), a small Tafel slope of ∼36 mV dec(-1), and long cycling lifespan more than 20 h. The promising results, in addition to the fact that Fe1-xCoxSe2/RGO is a high-performance, precious-metal-free electrocatalyst, pave the way for exciting opportunities in renewable hydrogen production applications.

Novel FeNi2S4/TMD-based ternary composites for supercapacitor applications

Ternary electrode materials based on graphene, FeNi2S4, and transition metal dichalcogenides (TMDs) were obtained via a one-pot synthesis method. Compared to binary materials, FeNi2S4–graphene (g)–2D-TMD nanocomposites exhibited better performance, which is a direct consequence of their unique ternary structures and the induced synergistic effect among their three components—ultrathin TMD nanosheets, highly conductive graphene networks, and FeNi2S4 nanoparticles. With the fabricated materials, we constructed electrodes to assess the electrochemical performance. The results are promising: the materials exhibited rapid electron and ion transport rates and large electroactive surface areas, testifying to their excellent electrochemical properties. In particular, the FeNi2S4–g–MoSe2 electrode demonstrated a maximum specific capacitance of 1700 F g−1 at a current density of 2 A g−1 (8.5 F cm−2 at a current density of 10 mA cm−2) and a capacitance retention of approximately 106% after 4000 cycles at a charge–discharge current density of 2 A g−1. These electrochemical results indicate that the ternary composite, FeNi2S4–g–MoSe2, is a promising candidate electrode material for high-performance supercapacitors.

One-pot hydrothermal synthesis of magnetically recoverable palladium/reduced graphene oxide nanocomposites and its catalytic applications in cross-coupling reactions

A facile, green, economical approach was designed to deposit palladium nanoparticles on magnetic reduced graphene oxide nanosheets (Pd-Fe3O4/rGO) via a one-pot hydrothermal synthesis method. The prepared Pd-Fe3O4/rGO nanocomposites were thoroughly characterized by Transmission electron microscopy, Scanning electron microscopy, Fourier-transform infrared spectroscopy, X-ray diffraction, and Raman spectroscopy. Importantly, the highly efficient catalytic property of the as-obtained Pd-Fe3O4/rGO catalyst was demonstrated for the Suzuki-Miyaura coupling reaction and Mizoroki-Heck coupling reaction. Significantly, the Suzuki-Miyaura coupling reactions could be efficiently performed in an environmentally friendly aqueous solution with no need for further additives. Besides, the nanocomposites could be conveniently separated from reaction system with an external permanent magnet for recycling and the inherent catalytic activity of the nanocomposites did not exacerbate after six repeated applications.

Integrated Energy Aerogel of N,S-rGO/WSe2/NiFe-LDH for Both Energy Conversion and Storage

High-performance active materials for energy-storage and energy-conversion applications require a novel class of electrodes: ones with a structure conducive to conductivity, large specific surface area, high porosity, and mechanical robustness. Herein, we report the design and fabrication of a new ternary hybrid aerogel. The process entails an in situ assembly of 2D WSe2 nanosheets and NiFe-LDH nanosheets on a 3D N,S-codoped graphene framework, accomplished by a facile hydrothermal method and electrostatic self-assembly technology. The obtained nanocomposite architecture maximizes synergistic effects among its three 2D-layer components. To assess the performance of this hybrid material, we deployed it as an advanced electrode in overall water splitting and in a supercapacitor. Results in both scenarios attest to its excellent electrochemical properties. Specifically, serving as a catalyst in an oxygen evolution reaction, our nanocomposite requires overpotentials of 1.48 and 1.59 V to obtain current densities of 10 and 100 mA cm-2, respectively. The hybrid material also efficiently electrocatalyzes hydrogen evolution reactions in base solution, necessitating overpotentials of -50 and -237 mV for current densities of 1.0 and 100 mA cm-2, respectively. The 3D hybrid, when applied to a symmetric supercapacitor device, achieves 125.6 F g-1 capacitance at 1 A g-1 current density. In summary, our study elucidates a new strategy to maximize efficiency via synergetic effects that is likely applicable to other 2D materials.