Development of excellent and cheap electrocatalysts for water electrolysis is of great significance for application of hydrogen energy. Here, we show a highly efficient and stable oxygen evolution reaction (OER) catalyst with multilayer-stacked hybrid structure, in which vertical graphene nanosheets (VGSs), MoS2 nanosheets, and layered FeCoNi hydroxides (FeCoNi(OH)x) are successively grown on carbon fibers (CF/VGSs/MoS2/FeCoNi(OH)x). The catalyst exhibits excellent OER performance with a low overpotential of 225 and 241 mV to attain 500 and 1000 mA cm−2 and small Tafel slope of 29.2 mV dec−1. Theoretical calculation indicates that compositing of FeCoNi(OH)x with MoS2 could generate favorable electronic structure and decrease the OER overpotential, promoting the electrocatalytic activity. An alkaline water electrolyzer is established using CF/VGSs/MoS2/FeCoNi(OH)x anode for overall water splitting, which generates a current density of 100 mA cm−2 at 1.59 V with excellent stability over 100 h. Our highly efficient catalysts have great prospect for water electrolysis.

3D assembly of graphene sheets (GSs) is important for preserving the merits of the single-atomic-layered structure. Simultaneously, vertical growth of GSs has long been a challenge for thermal chemical vapor deposition (CVD). Here, vertical growth of the GSs is achieved in a thermal CVD reactor and a novel 3D graphene structure, 3D graphene fibers (3DGFs), is developed. The 3DGFs are prepared by carbonizing electrospun polyacrylonitrile fibers in NH and subsequently in situ growing the radially oriented GSs using thermal CVD. The GSs on the 3DGFs are densely arranged and interconnected with the edges fully exposed on the surface, resulting in high performances in multiple aspects such as electrical conductivity (3.4 × 10 -1.2 × 10 S m ), electromagnetic shielding (60 932 dB cm g ), and superhydrophobicity and superoleophilicity, which are far superior to the existing 3D graphene materials. With the extraordinary properties along with the easy scalability of the simple thermal CVD, the novel 3DGFs are highly promising for many applications such as high-strength and conducting composites, flexible conductors, electromagnetic shielding, energy storage, catalysis, and separation and purification. Furthermore, this strategy can be widely used to grow the vertical GSs on many other substrates by thermal CVD.

Here, we report the synthesis of nanosheet-structured boron nitride spheres (NSBNSs) by a catalyzing thermal evaporation method from solid B powders. The NSBNSs consist of radially oriented ultrathin nanosheets with the sheet edges oriented on the surface. Formation of this unique structure occurs only at a certain reaction temperature. The diameter from 4 μm to 700 nm and the nanosheet thickness from 9.1 to 3.1 nm of the NSBNSs can be well-controlled by appropriately changing the mass ratio of boron powders and catalyst. The NSBNSs possess versatile adsorption capacity, exhibiting excellent adsorption performance for oil, dyes, and heavy metal ions from water. The oil uptake reaches 7.8 times its own weight. The adsorption capacities for malachite green and methylene blue are 324 and 233 mg/g, while those for Cu(2+), Pb(2+), and Cd(2+) are 678.7, 536.7, and 107.0 mg/g, respectively. The adsorption capacities of the NSBNSs for Cu(2+) and Pb(2+) are higher or much higher than those of the adsorbents reported previously. These results demonstrate the great potential of NSBNSs for water treatment and cleaning.

including natural source of solar, thermal, wind energies, and mechanical energy of human movements, and to compensate energy consumption in energy storage devices. [15][16][17][18][19] For example, the perovskite hybrid solar cells is integrated into graphene based supercapacitor. [20] The solid-state supercapacitors can be charged by perovskite hybrid solar cells and discharged from 0.75 V. The dye-sensitized solar cell also has been assembled with supercapacitor. [21] In addition, various devices were developed via integrating piezoelectric or triboelectric nanogenerators with electro chemical energy storage units. [22][23][24] They can harvest mechanical energy from our living environment such as human movements, [25] vehicle rotations, [26] water waves. [27] However, most current integrated systems are designed by crudely connecting different components through external circuit, such as nanogenerator (Figure 1a) and solar cell ( Figure 1b) based integration systems. The systems are usually rigid and cumbersome with vastly increased volume. [28] More importantly, the two components may be easily de-attached when being exposed to deformations, resulting in poor reliability and durability.Another even more important issue is that, while technologies to harvesting energy from environments are very sophisticated and these integrated systems were well demonstrated, another problem is that these energies possess a density highly dependent on the usage scenario. For example, the solar cells can work well under intense sunlight irradiation but most of the time the users have only indoor lighting available. Similarly, the nanogenerator can only collect ambient mechanical energy at sports mode while most people need to stay quietly to work. Therefore, an energy harvesting technology or system which possesses low dependency to environment and usage scenario is highly expected.Otherwise than other environmental elements, air is full of any corners of our space with almost constant concentration. An "air chargeable" system is expected to be highly reliable.Here, we propose a highly integrated system of "air charging" zinc-ion capacitor/battery. By scavenging energy from pervasive air, a zinc-ion capacitor/battery can be conveniently and easily charged without applying additional power source. The A rationally designed "air chargeable" energy storage device is demonstrated, which can be effectively charged by harvesting pervasive energy from the ambient environment. For an "air chargeable" zinc-ion capacitor system, the system simply consists of a flexible bifunctional "U" shaped electrode (with the functions of energy harvesting and storage), a zinc metal electrode in middle, and two different polyelectrolytes (polyacrylamide and sodium polyacrylate) sandwiched between the zinc metal and "U" shaped electrode. When the zinc-ion capacitor is exhausted, it can be quickly charged to 88% within 10 min by simply opening the sealing tape and allowing the air diffuse in. The capacitor exhausting-air charging processes are repeate...

A change in temperature can modify the ion density near the electrode surface, and create a potential difference across a supercapacitor.

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Three-dimensional ordering of two-dimensional nanomaterials has long been a challenge. Simultaneously, diamond nanomaterials are difficult to synthesize due to the harsh synthesizing conditions required. Here, we report substrate-crystal-orientation dependent growth of diamond nanosheets (DNSs) by chemical vapor deposition, which generates different DNS arrays on different substrates. The DNSs are grown by the in-plane epitaxy of the diamond {111} planes. So the arrays are highly ordered and solely determined by the spatial orientation of the {111} planes in the diamond FCC structure. The DNSs grown on the {110}, {111}, {001}, and {113} oriented substrates show inclination angles ranging from 90 to 29.5°. The DNSs with larger inclination angles grow preferentially, forming parallelogram arrays with inclination angles of 90° on the {110} substrates and parallel-line arrays with inclination angles of 80° on the {113} substrates. The density, thickness, size, and morphology of the DNSs have been well controlled. The present understanding and materials are highly promising for many applications such as sensors, catalysis, photonics, thermal management, and electronics.

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