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Due to their synergistic and tunable effects, bimetallic alloy systems have recently attracted considerable attention as superior catalysts. Herein, Pd-Co bimetallic alloy nanoparticles were uniformly deposited onto CuO nanosheet supports. This nanostructured catalyst was first shown to be an effective catalyst to convert N2 to NH3 in 0.1 M KOH with a yield of 10.04 μg h-1 mg-1cat. and a faradaic efficiency of 2.16%. The catalyst also performed well in the Suzuki-Miyaura coupling reaction at room temperature without an inert atmosphere and any toxic solvents. Thus, the catalyst is consistent with the principles of green chemistry. Due to the synergistic effects, this bimetallic Pd-Co catalyst shows higher catalytic activity than its monometallic counterparts. Moreover, the Pd/Co ratio was tuned to achieve the best catalytic performance. Finally, the Pd-Co/CuO catalyst presented good stability and recyclability. The superior catalytic activity of the bimetallic alloy catalyst make it an alternative material for catalytic applications in the future.

Molybdenum disulfide (MoS2) is an extensively studied promising non-noble catalyst because of its remarkable performance for the hydrogen evolution reaction (HER). However, the primary factors that affect its catalytic activity have not been analysed comprehensively and quantitatively; this impedes the further design and development of MoS2-based electrocatalysts. Herein, using novel porous MoS2 nanosheets prepared via a controlled and scalable KOH-assisted exfoliation pathway, we methodically studied the contributions of bore edge active sites to the catalytic activity towards the HER. To make the preparation safer, 2H-MoS2 instead of 1T-MoS2 that needs to be prepared with butyllithium has been chosen to synthesize porous MoS2 nanosheets. A comparative study revealed that the overpotential of porous MoS2 nanosheets exhibited an extreme point, which was predominantly due to the different densities of bore edge active sites derived from different quantities of KOH. Amazingly, the HER performance of MoS2 nanosheets experienced the most obvious improvement after these nanosheets were treated with 37.5 wt% KOH. A series of tests and density functional theory calculations were conducted to explain the experimental results, which were consistent with each other. Furthermore, this method has been proven to be universal since porous WS2 and SnS2 nanosheets have been prepared by the same route. This study presents novel insights and reveals a new, controlled, and scalable chemical avenue for programming electrocatalysts based on MoS2 or other layered materials.

For the first time, a uniform graphene aerogel (GA) supported Prussian blue (PB) nanocube structure was synthesized by fitting the nanocube into the GA with a specific pore size and employing it in a freestanding sodium ion battery cathodic electrode. In this electrode, the graphene framework not only offers mechanical support, but also plays the role of a binder-free current collector. The theoretical specific capacity of Prussian blue was exceeded with an ultrahigh specific capacity of 214 mA h g-1 at 0.5 C. With the help of the electronic double layer capacitance of the graphene framework, this ultrahigh value can be achieved. We studied the influence of the mass loading of the PB nanocube on the specific capacity, finding that the GA-induced freestanding electrode has the potential to load a maximum of 72 wt% of the PB nanocube. Furthermore, we separated the capacitance and the capacity of the electrode through kinetic analysis, and discovered that the GA-induced carbon collector contributed to a surface-controlled capacitance, which accounted for 55% of the total capacity.

Micro-supercapacitors (MSCs) possessing the remarkable features of high electrochemical performance and relatively small volume are promising candidates for energy storage in micro-devices. Tremendous effort has been devoted in recent years to design and to fabricate MSCs with different active electrode materials, including carbon-based materials, conducting polymers, and graphene/metal oxide composites. Moreover, various methods have been developed to prepare MSCs, such as photolithography, laser direct writing, printing methods. This review presents a summary of the recent developments in MSC technology, including electrode materials, fabrication methods, and patterning. Finally, future developments, perspectives, and challenges in the MSC industry are also discussed.

Due to their synergistic and tunable effects, bimetallic alloy systems have recently attracted considerable attention as superior catalysts. Herein, Pd-Co bimetallic alloy nanoparticles were uniformly deposited onto CuO nanosheet supports. This nanostructured catalyst was first shown to be an effective catalyst to convert N2 to NH3 in 0.1 M KOH with a yield of 10.04 μg h-1 mg-1cat. and a faradaic efficiency of 2.16%. The catalyst also performed well in the Suzuki-Miyaura coupling reaction at room temperature without an inert atmosphere and any toxic solvents. Thus, the catalyst is consistent with the principles of green chemistry. Due to the synergistic effects, this bimetallic Pd-Co catalyst shows higher catalytic activity than its monometallic counterparts. Moreover, the Pd/Co ratio was tuned to achieve the best catalytic performance. Finally, the Pd-Co/CuO catalyst presented good stability and recyclability. The superior catalytic activity of the bimetallic alloy catalyst make it an alternative material for catalytic applications in the future.

Few-layered polyelectrolyte functionalized MoS2 nanosheets were obtained for the first time through in situ polymerization of MoS2 nanosheets with poly(acrylic acid) and poly(acrylamide), both of which demonstrated excellent dispersibility and stability in water. After designing and optimizing the components of this series of polyelectrolyte functionalized MoS2 nanosheets, by exploiting the electrostatic interactions present in the modified MoS2 nanosheets, we further created a series of layer-by-layer (LBL) self-assembling MoS2-based films. To this end, uniform MoS2 nanosheet-based LBL films were precisely deposited on substrates such as quartz, silicon, and ITO. The polyelectrolyte functionalized MoS2 nanosheet assembled LBL film-modified electrodes demonstrated enhanced electrocatalytic activity for H2O2. As such, they are conducive to efficient sensors and advanced biosensing systems.

Two-dimensional (2D) metal chalcogenides (MC) such as MoS2 have been recognized as promising materials for near future applications. However, general strategies to functionalize them are still scarce, while the nature of functionalization still remains unclear. Herein, we demonstrate a simple and universal functionalization route through complexation reaction between the amino-containing organic agents and MCs. Degrees of functionalization are tunable by adjusting the organic group types and ratios. No further defects are introduced and the functionalized 2D MCs are dispersible in corresponding typical solvents. Both experimental results and geometry optimization calculations indicate that the grafting of functional groups through the coordination effect truly exist, while the surface properties and resulting photoelectric properties of 2D MCs are greatly altered. More intriguingly, our proposed functionalization process is demonstrated to be universal and can be applied to different MCs, thus opening new avenues for the application of 2D MCs.

Transition metal dichalcogenides, MX2 (M = Fe, Co, Ni, X = S, Se, Te), have been proven to be promising substitutes for noble metals in hydrogen evolution reactions (HERs). However, forthright comparisons of metal sulfides, metal selenides, and metal tellurides are rarely conducted, let alone the mechanism of the important role of their non-metal ligands. In this paper, we report the pilot study of a controllable method for the preparation of a series of NiX2 (X = S, Se, Te) nanosheets via a facile anion-exchange reaction. Consequently, the HER activities and stabilities of NiS2, NiSe2, and NiTe2 nanosheets were tested in both acid and alkaline solutions. The required overpotentials to reach 10 mA cm−2 in 0.5 M H2SO4 for NiS2, NiSe2, and NiTe2 were 213, 156, and 276 mV, respectively. The best performance of NiSe2 was also confirmed in 1 M KOH. Besides NiS2 and NiTe2 nanosheets, the HER properties of NiSe2 nanosheets are superior to most of the available nickel catalysts. Interestingly, the results from electrochemical measurements were found to be fully consistent with the data based on density function theory calculation. Among various factors that might influence the HER activities of nickel dichalcogenides, the free energies of hydrogen adsorption and conductivities have played important roles.