The π-conjugated polymer polydiphenylbutadiyne was prepared at the nanoscale confined inside the 1.2 nm 1-D pores of the aluminophosphate AlPO4-54. Molten 1,4-diphenyl-1,3-dibutadiyne (DPB) was inserted in the pores of AlPO4-54 at pressures below 0.3 GPa as confirmed by X-ray diffraction. Heating to 190 °C under a pressure of 0.4 GPa induced polymerization of DPB in the pores. Infrared microscopy indicates full polymerization in the pores and the presence of characteristic saturated C–H defects common to other nanostructured PDPB materials exhibiting important photocatalytic properties. This nanostructured PDPB confined in the hygroscopic AlPO4-54 host could be of interest for applications in gas sensing, photocatalysis and hydrogen generation.

Low-dimensional boron nitride (BN) chains were prepared in the one-dimensional pores of the siliceous zeolites theta-one (TON) and Mobil-twelve (MTW) by the infiltration, followed by the dehydrocoupling and pyrolysis of ammonia borane under high-pressure, high-temperature conditions. High-pressure X-ray diffraction in a diamond anvil cell and in a large-volume device was used to follow in situ these different steps in order to determine the optimal conditions for this process. Based on these results, millimeter-sized samples of BN/TON and BN/MTW were synthesized. Characteristic B–N stretching vibrations of low-dimensional BN were observed by infrared and Raman spectroscopies. The crystal structures were determined using a combination of X-ray diffraction and density functional theory with one and two one-dimensional zig-zag (BN)x chains per pore in BN/TON and BN/MTW, respectively. These 1-D BN chains potentially have interesting photoluminescence properties in the far ultraviolet region of the electromagnetic spectrum.

This paper presents low-temperature measurements of magnetoresistivity in heavily doped n-type GaN grown by basic GaN growth technologies: molecular beam epitaxy, metal-organic vapor phase epitaxy, halide vapor phase epitaxy and ammonothermal. Additionally, GaN crys-tallized by High Nitrogen Pressure Solution method was also examined. It was found that all the samples under study exhibit negative magnetoresistivity at low temperature (10 K < T < 50 K) and for some samples this effect is observed up to 100 K. This negative magnetoresistivity effect is analyzed in the frame of the weak localization phenomena in the case of three-dimensional electron gas in a highly doped semiconductor. This analysis allows to determine the phasing coherence time τφ for heavily doped n-type GaN. The obtained τφ value is proportional to T-1.34, indicating that the electron–electron interaction is the main dephasing mechanism for the free carriers.

Abstract Since the emergence of graphene, we have seen several proposals for the realization of Landau lasers tunable over the terahertz frequency range. The hope was that the non-equidistance of the Landau levels from Dirac fermions would suppress the harmful non-radiative Auger recombination. Unfortunately, even with this non-equidistance an unfavorable non-radiative process persists in Landau-quantized graphene, and so far no cyclotron emission from Dirac fermions has been reported. One way to eliminate this last non-radiative process is to sufficiently modify the dispersion of the Landau levels by opening a small gap in the linear band structure. A proven example of such gapped graphene-like materials are HgTe quantum wells close to the topological phase transition. In this work, we experimentally demonstrate Landau emission from Dirac fermions in such HgTe quantum wells, where the emission is tunable by both the magnetic field and the carrier concentration. Consequently, these results represent an advance in the realization of terahertz Landau lasers tunable by magnetic field and gate-voltage.

Electrochemical synthesis of NH3 is a carbon-free alternative to the traditional Haber-Bosch process. Obtaining NH3 from environmental pollutants, such as nitrates or nitrites, is a more practical route than from the nitrogen reduction reaction (NRR) due to the difficult cleavage of the inert triple bond of nitrogen gas. Here, we report a novel heterogeneous catalyst based on iron (Fe) single-atoms supported on two-dimensional MoS2 (Fe-MoS2) for the nitrate reduction reaction (NO3RR). Fe-MoS2 exhibits remarkable performance with a maximum Faradaic