The photoluminescence (PL) spectra of the undoped ZnO films deposited on Si substrates by dc reactive sputtering have been studied. There are two emission peaks, centered at 3.18 eV (UV) and 2.38 eV (green). The variation of these peak intensities and that of the I–V properties of the ZnO/Si heterojunctions were investigated at different annealing temperatures and atmospheres. The defect levels in ZnO films were also calculated using the method of full-potential linear muffin-tin orbital. It is concluded that the green emission corresponds to the local level composed by oxide antisite defect OZn rather than oxygen vacancy VO, zinc vacancy VZn, interstitial zinc Zni, and interstitial oxygen Oi.

The utility of electronically conductive metal-organic frameworks (EC-MOFs) in high-performance devices has been limited to date by a lack of high-quality thin film. The controllable thin-film fabrication of an EC-MOF, Cu (HHTP) , (HHTP=2,3,6,7,10,11-hexahydroxytriphenylene), by a spray layer-by-layer liquid-phase epitaxial method is reported. The Cu (HHTP) thin film can not only be precisely prepared with thickness increment of about 2 nm per growing cycle, but also shows a smooth surface, good crystallinity, and high orientation. The chemiresistor gas sensor based on this high-quality thin film is one of the best room-temperature sensors for NH among all reported sensors based on various materials.

The massive depletion of fossil fuels has led to severe energy and environmental crisis, which urgently needs an in-depth research on the exploration of sustainable energy. Among various energy sources, hydrogen (H 2) is considered to be one of the most potential alternatives to traditional fossil fuels owing to its high energy density and environmental friendliness. [1] Electrochemical hydrogen evolution reaction (HER) is an attracting and scalable technology to split water into H 2 , which can use the renewable electricity as power to realize a hydrogen-based economy. [2] Metals with good conductivity and proton activation are promising electrocatalysts for HER. The past years have witnessed the great progress on metal-based catalysts for HER, where the noble metals, such as platinum (Pt) with near-zero overpotential and a very low Tafel slope for HER, are well known to meet the requirements in terms of commercial application. [3] However, the cherish scarcity and poor stability The electrochemical hydrogen evolution reaction (HER) is an attractive technology for the mass production of hydrogen. Ru-based materials are promising electrocatalysts owing to the similar bonding strength with hydrogen but much lower cost than Pt catalysts. Herein, an ordered macroporous superstructure of N-doped nanoporous carbon anchored with the ultrafine Ru nanoclusters as electrocatalytic micro/nanoreactors is developed via the thermal pyrolysis of ordered macroporous single crystals of ZIF-8 accommodating Ru(III) ions. Benefiting from the highly interconnected reticular macro-nanospaces, this superstrucure affords unparalleled performance for pH-universal HER, with order of magnitude higher mass activity compared to the benchmark Pt/C. Notably, an exceptionally low overpotential of only 13 mV@10 mA cm −2 is required for HER in alkaline solution, with a low Tafel slope of 40.41 mV dec −1 and an ultrahigh turnover frequency value of 1.6 H 2 s −1 at 25 mV, greatly outperforming Pt/C. Furthermore, the hydrogen generation rates are almost twice those of Pt/C during practical overall alkaline water splitting. A solar-to-hydrogen system is also demonstrated to further promote the application. This research may open a new avenue for the development of advanced electrocatalytic micro/nanoreactors with controlled morphology and excellent performance for future energy applications.

Recent experimental studies show that carbon nanotubes impact the aggregation process of proteins associated with neurodegenerative diseases. However, the details of molecular interactions between proteins and carbon nanotubes are still not well understood. In this study, we investigate the initial adsorption features and dynamics of the Alzheimer's amyloid-beta peptide spanning residues 25-35 (Abeta25-35) on a single-walled carbon nanotube (SWNT) surface using fully atomic molecular dynamics simulations (MD) in explicit solvent. The initial configurations of the Abeta25-35 peptides consist of two preformed bilayer beta-sheets, each with four or five beta-strands in parallel or mixed antiparallel-parallel orientations. Our simulations show, for what we believe is the first time, that two disjointed Abeta25-35 beta-sheets with mixed antiparallel-parallel strands can assemble into beta-barrels wrapping the SWNT. In contrast, both simulations of Abeta25-35 without SWNT, and simulations of SWNT-Abeta25-35 with purely parallel beta-strands, lead to disordered aggregates. We find that Abeta25-35 beta-barrel formation involves at least two steps: i), curving of the Abeta25-35 beta-sheets as a result of strong hydrophobic interactions with carbon nanotube concomitantly with dehydration of the SWNT-peptide interface; and ii), intersheet backbone hydrogen bond formation with fluctuating intrasheet hydrogen bonds. Detailed analysis of the conversion shows that beta-barrel formation on SWNT surface results from the interplay of dehydration and peptide-SWNT/peptide-peptide interactions. Implications of our results on amyloid fibril inhibition are discussed.

Photoconductivity is ac haracteristic property of semi-conductors.H erein, we present ap hoto-conducting crystalline metal-organic framework (MOF) thin film with an on-off photocurrent ratio of two orders of magnitude.These oriented, surface-mounted MOF thin films (SURMOFs), contain porphyrin in the framework backbone and C 60 guests,l oaded in the pores using al ayer-by-layer process.B y comparison with results obtained for reference MOF structures and based on DFT calculations,w ec onclude that donoracceptor interactions between the porphyrin of the host MOF and the C 60 guests give rise to ar apid charge separation. Subsequently,h oles and electrons are transported through separate channels formed by porphyrin and by C 60 ,r espectively.The ability to tune the properties and energy levels of the porphyrin and fullerene,a long with the controlled organization of donor-acceptor pairs in this regular framework offers potential to increase the photoconduction on-off ratio.

Lithium–sulfur (Li–S) batteries are appealing candidates for next‐generation high‐energy rechargeable batteries, but practical applications are still limited by poor cyclic life, which is caused by severe polysulfide shuttling in high‐sulfur‐loading batteries. Herein, a facile route is presented to fabricate high‐performance Li–S batteries using a crystalline microporous membrane, which is prepared using a conductive metal–organic framework (MOF) material. With ordered microporous structure, large specific surface area, good sulphiphilicity, and excellent conductivity, the MOF membrane is grown in situ on the commercial separator and is an ideal light‐weight barrier (0.066 mg cm−2) for suppressing the polysulfide shuttling, which can significantly promote the capacities, rate capabilities, and cycling stabilities of Li–S batteries. Taking the advantage of this functional separator, the high‐sulfur‐loading Li–S battery (8.0 mg cm−2 and 70 wt% of sulfur in cathode) delivers a high area capacity of 7.24 mAh cm−2 after 200 cycles, thus providing a promising path toward advanced Li–S batteries.

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