Cost effective hydrogen evolution reaction (HER) catalyst without using precious metallic elements is a crucial demand for environment-benign energy production. Molybdenum sulfide is one of the promising candidates for such purpose, particularly in acidic condition, but its catalytic performance is inherently limited by the sparse catalytic edge sites and poor electrical conductivity. We report synthesis and HER catalysis of hybrid catalysts composed of amorphous molybdenum sulfide (MoSx) layer directly bound at vertical N-doped carbon nanotube (NCNT) forest surface. Owing to the high wettability of N-doped graphitic surface and electrostatic attraction between thiomolybdate precursor anion and N-doped sites, ∼2 nm scale thick amorphous MoSx layers are specifically deposited at NCNT surface under low-temperature wet chemical process. The synergistic effect from the dense catalytic sites at amorphous MoSx surface and fluent charge transport along NCNT forest attains the excellent HER catalysis with onset overpotential as low as ∼75 mV and small potential of 110 mV for 10 mA/cm(2) current density, which is the highest HER activity of molybdenum sulfide-based catalyst ever reported thus far.

Novel 3D self-assembled nanopatterning is presented via tailored crumpling of chemically modified graphene. Block-copolymer self-assembly formed on a layer of chemically modified graphene provides highly dense and uniform 2D nanopatterns, and the controlled crumpling of the chemically modified graphene by mechanical instabilities realizes the controlled 3D transformation of the self-assembled nanopatterns.

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A scalable and controllable nanoscale perforation method for graphene is developed on the basis of the two-step thermal activation of a graphene aerogel. Different resistance to the thermal oxidation between graphitic and defective domains in the weakly reduced graphene oxide is exploited for the self-limiting nanoscale perforation in the graphene basal plane via selective thermal degradation of the defective domains. The resultant nanoporous graphene with a narrow pore-size distribution addresses the long-standing challenge for the high-level doping of graphene with lattice-mismatched large-size heteroatoms (S and P). Noticeably, this novel heteroatom doping strategy is demonstrated to be highly effective for oxygen reduction reaction (ORR) catalysis. Not only the higher level of heteroatom doping but also favorable spin and charge redistribution around the pore edges leads to a strong ORR activity as supported by density functional theory calculations.

nonprecious catalysts toward the hydrogen evolution reaction (HER) for a widespread of sustainable energy storage and conversion. [6] To date, a variety of nonprecious-metalbased catalysts, especially, the family of earth-abundant transition metal compounds of nitrides, [7,8] carbides, [9,10] chalcogenides, [11][12][13][14] and phosphides, [15][16][17][18][19] have been explored for HER catalysts. It has been reported that novel material designs relying on chemical synthesis or crystalline engineering (facets, polymorph, interface, defect, doping, surface modification) can enhance HER activity. Nonetheless, in order to avoid the undesired charge transfer loss and gas bubble trap, a welldesigned, atomically and electronically coupled interface between fully tailored catalyst morphology and high surface area of conductive support turned out to be essential. [20] In this regard, unlike widely used oxygen functionalized carbon supports with severely damaged electrical properties, electron-rich N-doped carbon nanotubes (CNTs) and graphene not only provide additional electrons to graphitic carbons to maintain high electroconductivity but also afford novel synthesis platform for the synergistic hybrid structures of ultimate practical utilization. [12] We present a unique nanostructured core-shell hybrid catalysts composed of transition metal phosphosulfide (CoP@PS, MoP@PS, CoMoP@PS) decorated at N-doped carbon nanotubes (NCNTs). Nanoscale thick amorphous MS x (M = Co, Mo, CoMo) layers were directly deposited on the large area NCNT surfaces by low-temperature wet chemical process and subsequent phosphidation. Quasi-amorphous phosphosulfide (PS) nanoshells are formed around the crystalline core particles, whose S-doping effect greatly enhances the HER activity of nanoparticles to attain the noticeable HER activity of ≈ −80 mV @ −10 mA cm −2 with excellent durability. It is noteworthy that this is the first report for core-shell transition metal phosphosulfide nanostructure formation with a clear evolution of amorphous PS surface. The underlying catalytic mechanisms were investigated by density functional theory (DFT), which revealed the principal role of hybrid interfaces for the catalytic activity. Taken together, this hybrid offers one of the highest active nonnoble metal electrocatalysts ever reported thus far.A cost effective hydrogen evolution reaction (HER) catalyst that does not use precious metallic elements is a crucial demand for environment-benign energy production. The family of earth-abundant transition metal compounds of nitrides, carbides, chalcogenides, and phosphides is one of the promising candidates for such a purpose, particularly in acidic conditions. However, its catalytic performance is still needed to be enhanced through novel material designs and crystalline engineering. Herein, a chemically and electronically coupled transition metal phosphosulfide/N-doped carbon nanotubes (NCNT) hybrid electrocatalyst is fabricated via a two-step synthesis. The uniquely designed synthesis leads to the materia...

N‐doped sites at carbon nanotubes and graphene trigger the spontaneous decoration of bimetal (Pt and Pd) particles by the facile electroless redox reaction. The created hybrid catalyst yields remarkable current density (≈2.44 mA cm−2), lower onset potential (≈0.13 V), higher electron transfer number ≈4), and long‐term stability for oxidation–reduction reactions.

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We fabricated polymer piezoelectric energy harvesters (PEHs) that can generate electric power at wind speed of less than 4.7 m/s due to their high sensitivity to wind. In order to optimize their operating conditions, we evaluated three distinct PEH operation modes under the boundary conditions of single-side clamping. We found that a PEH connected to an external load of 120 kΩ shows the largest output power of 0.98 μW at 3.9 m/s, with wind incident on its side (mode I). We attribute this result to large bending and torsion involved in this operation mode.