Articles you may be interested inAbsorption cross section and signal enhancement in Er-doped Si nanocluster rib-loaded waveguides Appl. Phys. Lett. 86, 261103 (2005); 10.1063/1.1957112 Deposition and 1.54 μm Er 3+ luminescent properties of erbium-doped hydrogenated amorphous silicon thin films by electron cyclotron resonance plasma enhanced chemical vapor deposition of SiH 4 with concurrent sputtering of erbium J. Vac. Sci. Technol. A 17, 3230 (1999); 10.1116/1.582047 1.54 μ m Er 3+ photoluminescent properties of erbium-doped Si/SiO 2 superlattices Appl. Phys. Lett. 74, 1573 (1999); 10.1063/1.123620Effect of hydrogenation on room-temperature 1.54 μm Er 3+ photoluminescent properties of erbium-doped silicon-rich silicon oxide

Despite highly promising characteristics of three-dimensionally (3D) nanostructured catalysts for the oxygen evolution reaction (OER) in polymer electrolyte membrane water electrolyzers (PEMWEs), universal design rules for maximizing their performance have not been explored. Here we show that woodpile (WP)-structured Ir, consisting of 3D-printed, highly-ordered Ir nanowire building blocks, improve OER mass activity markedly. The WP structure secures the electrochemically active surface area (ECSA) through enhanced utilization efficiency of the extended surface area of 3D WP catalysts. Moreover, systematic control of the 3D geometry combined with theoretical calculations and various electrochemical analyses reveals that facile transport of evolved O2 gas bubbles is an important contributor to the improved ECSA-specific activity. The 3D nanostructuring-based improvement of ECSA and ECSA-specific activity enables our well-controlled geometry to afford a 30-fold higher mass activity of the OER catalyst when used in a single-cell PEMWE than conventional nanoparticle-based catalysts.

A hydrogen (H ) gas sensor based on a silicon (Si) nanomesh structure decorated with palladium (Pd) nanoparticles is fabricated via polystyrene nanosphere lithography and top-down fabrication processes. The gas sensor shows dramatically improved H gas sensitivity compared with an Si thin film sensor without nanopatterns. Furthermore, a buffered oxide etchant treatment of the Si nanomesh structure results in an additional performance improvement. The final sensor device shows fast H response and high selectivity to H gas among other gases. The sensing performance is stable and shows repeatable responses in both dry and high humidity ambient environments. The sensor also shows high stability without noticeable performance degradation after one month. This approach allows the facile fabrication of high performance H sensors via a cost-effective, complementary metal-oxide-semiconductor (CMOS) compatible, and scalable nanopatterning method.

Gain-determining coefficients in Er-doped, nanocrystal-Si (nc-Si) sensitized silica waveguide amplifiers are investigated. Single-mode, Er-doped silica waveguides with nc-Si embedded in them were prepared by electron cyclotron resonance plasma-enhanced chemical vapor deposition of Er-doped a-Si:Ox (x<2) followed by a high-temperature anneal to precipitate nc-Si. Exciting the Er ions via nc-Si by pumping the waveguide from the top with the 477 nm line of an Ar laser resulted in an enhancement of the transmitted 1535 nm signal of up to 14 dB/cm, indicating a possible net gain of up to 7 dB/cm. From the dependence of the signal enhancement upon the pump power, an emission cross section of 2×10−19 cm2 at 1535 nm and an effective excitation cross section of ⩾10−17 cm2 at 477 nm is obtained.

Chemical exfoliation approaches such as Li-intercalation for the production of two-dimensional MoS 2 are highly attractive due to their high yield of monolayer forms, cost-effectiveness, and mass-scalability. However, the loss of the semiconducting property and poor dispersion stability in solvent have limited the extent of their potential applications. Here, we report simultaneous phase recovery and surface functionalization for the preparation of a highly stable 2H-MoS 2 dispersion in water. This study shows that high-yield restoration of the semiconducting 2H phase from a chemically exfoliated MoS 2 (ce-MoS 2 ) can be induced by a mild-temperature (180 °C) solvent thermal treatment in N -methyl-2-pyrrolidone (NMP). In addition to a phase transition, this solvent thermal treatment in NMP realizes concurrent surface functionalization of the 2H-MoS 2 surface, which provides an outstanding dispersion stability to 2H-MoS 2 in water for more than 10 months. Finally, we report the humidity sensor based on the functionalized 2H-MoS 2 , which shows a substantial response enhancement compared with a nonfunctionalized 2H-MoS 2 or ce-MoS 2 .