Octahedral MOF@COF core–shell hetero-framework photocatalysts were designed which achieved superior photocatalytic H2-evolution activity.

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Photocatalytic ammonia synthesis from N2 is a carbon-neutral strategy, although its efficiency is impeded by the activation of inert NN triple bonds. In N2 activation, the electron acceptance process is often strongly coupled with the electron donation process, leading to a high potential activation energy barrier and low photocatalytic activity. Herein, we proposed a strategy to decouple these two processes by bimetallic organic frameworks (BMOFs) for boosting N2 activation. The rationally designed BMOFs are composed of two functional metal nodes, in which the hard acid metal node with a high ionization potential (I n) accepts the electron from N2 and the soft acid metal node with a low I n donates the electron to N2. Owing to the bimetal synergistic effect, the potential activation energy barrier of N2 is reduced, as confirmed by the in situ Fourier transform infrared (FTIR) spectra and density functional theory (DFT) calculations. Via testing six kinds of bimetal combinations, it is found that, as the ionization potential difference (ΔI n) between the two metals is ≥6 eV and the proportion of high I n metal reaches ∼20%, the bimetal synergistic effect becomes dominant. In all the as-prepared BMOFs, the optimal BMOF­(Sr)–0.2Fe photocatalyst exhibits an NH3 evolution rate up to 780 μmol g–1 h–1. This work may unveil a corner of the hidden mechanism for the chemical bond activation in a broad range of catalytic processes.

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The evolution of temperature and thermal stresses during friction stir welding of Al6061-T6 was investigated by means of in situ, time resolved neutron diffraction technique. A method was developed to deconvolute the temperature and stress from the lattice spacing changes measured by neutron diffraction. The deep penetration capability of neutrons made it possible for the first time to obtain the temperature and thermal stresses inside a friction stir weld.

Carbonization of nature-inspired polydopamine can yield thin films with high electrical conductivity. Understanding of the structure of carbonized PDA (cPDA) is therefore highly desired. In this study, neutron diffraction, Raman spectroscopy, and other techniques indicate that cPDA samples are mainly amorphous with some short-range ordering and graphite-like structure that emerges with increasing heat treatment temperature. The electrical conductivity and the Seebeck coefficient show different trends with heat treatment temperature, while the thermal conductivity remains insensitive. The largest room-temperature ZT of 2 × 10 was obtained on samples heat-treated at 800 °C, which is higher than that of reduced graphene oxide.

Rational manipulation of the photogenerated charge transfer inside the photocatalyst is key to enhancing the photocatalytic performance. Herein, inspired by the charge transport chain in natural photosynthesis, a novel multi-stepwise...

On Friday June 26, 2009, the neutron beam shutter for the VULCAN diffractometer at the SNS was opened for the first time. Initial measurements to characterize the instrument performance are reported. It is shown that the measurement results are by and large in agreement with design calculations. New research opportunities with VULCAN are discussed.