Electrical conductivity measurements show that the {100} faces of a perfect SrTiO3 cube are insulating, but the {110} faces of a SrTiO3 truncated rhombic dodecahedron are considerably more conductive. Interestingly, compared to electrodes touching the proximal {110} faces, adjacent {110} face contacts give notably higher current. Unexpectedly, while the {110} faces of a truncated rhombic dodecahedron remain much more conductive than its {100} faces, the adjacent conductive {110} facets may cause the poorly conductive {100} facets to become more conductive through slight current leakage to the adjacent conductive faces. Consistent with previous insulating behavior observed for a {110}-bound Cu2O rhombic dodecahedron, the {110} faces of a Cu2O rhombicuboctahedral microcrystal remain insulating. Thus, the influence of adjacent conductive facet may be avoided using sharper electrodes. Still, the adjacent facet effect may always be present even with the use of sharp electrodes. Current-rectifying asymmetric I–V curves were recorded with electrodes contacting the {100} and {110} faces of a SrTiO3 truncated rhombic dodecahedron. The electrical facet effects can be understood with different degrees of band bending at these crystal surfaces and thus different barrier heights to charge carrier transport across these surfaces. Finally, high-resolution transmission electron microscopy (HR-TEM) images over the surfaces of SrTiO3 truncated rhombic dodecahedra and cubes were taken, showing notable shifts in atomic positions within the few layers of surface lattice planes relative to the atomic positions of the interior lattice, suggesting that the lattice deviations within the thin surface layer as predicted by density functional theory (DFT) calculations may be visually observable.

As a source of clean and sustainable energy, reliable hydrogen production requires highly efficient and stable electrocatalysts. In recent years, molybdenum disulfide (MoS 2 ) has been demonstrated as a promising electrocatalyst for hydrogen evolution reactions (HERs). Here, we demonstrate that a three-dimensional (3D) MoS 2 quantum dot (MoS 2 QD) aerogel is an efficient cathode electrocatalyst that can be used to enhance the HER in acid, neutral, and alkaline (e.g., real seawater) environments. In studying the effects of the exfoliated MoS 2 dimension for the HER, we found that the biofunctionalized exfoliated MoS 2 QD shows much higher cathodic density, a more lower energy input, and a lower Tafel slope for the HER than the larger size of the chlorophyll-assisted exfoliated MoS 2 , highlighting the importance of the size of the MoS 2 aerogel support for accelerating the HER performance. Moreover, the electrocatalytic activity of MoS 2 QD-aerogel is superior to that of Pt in neutral conditions. In real seawater, the MoS 2 QD-aerogel sample exhibits stable HER performance after consecutive scanning for 150 cycles, while the HER activity of the Pt dramatically decreases after 50 cycles. These results showed for the first time how the 3D MoS 2 configuration in MoS 2 aerogel can be used to effectively produce hydrogen for clean energy applications.

CeO2 octahedral particles with average opposite corner lengths of 52, 67, 75, 85, 100, and 110 nm have been synthesized by heating a water–ethanol mixture of Ce­(NO3)3 solution at 150 °C for 1 h. Simply varying the volume of Ce­(NO3)3 solution used tunes the particle size. Experimental observations support direct formation of CeO2 from Ce3+ ions. Both light absorption and band-gap-related photoluminescence bands of these CeO2 octahedra red-shift continuously with increasing particle size. Optical band gap varies from 3.42 eV for 52 nm octahedra to 2.94 eV for 110 nm octahedra, so band gap tunability is possible over a very large size range. Mott–Schottky plots were obtained from electrochemical measurements to yield a band diagram of 52, 85, and 110 nm CeO2 octahedra with different valence band and conduction band energies, showing that particle size of semiconductor nanocrystals can significantly tune their band positions. The notable change in valence band positions for the 52 and 110 nm CeO2 octahedra may contribute to their potential difference in electrochemical oxygen evolution reaction activity.

By preparing an aqueous solution of cadmium acetate, thioacetamide (TAA), and nitric acid at 23 to 29 ºC, then heating the solution to 110 ºC for 40 min, unprecedented {110}-bound...

Due to the population explosion of the 21st century, nearly one billion people are over 64 years of age and bone fracture is one of the most frequent problems facing both sexes because of osteoporosis. However, difficulty in enhancing bone regeneration to repair bone fracture poses challenges and thus, a two-dimensional monolayer material (i.e. tungsten disulfide (WS2)) could be one of the candidates offering a possible solution to the problem. Here, we prepare high-quality monolayer WS2 thin sheets in a large quantity with the assistance of extracted chlorophyll molecules, the natural pigment used in photosynthesis, via a liquid-phase exfoliation method. Then, the exfoliated WS2 sheets were mixed with polycaprolactone (PCL)/calcium silicate (CS) to form a biocompatible WS2-based composite. The in vivo experiments show that the bone regeneration of the WS2-based composite was 120% superior to commercially available mineral trioxide aggregate (MTA) bone cement. Moreover, the mechanical properties of the WS2-based composite exhibited ~300% enhancement over PCL/CS, which is one of the most commonly used bone regeneration materials. Our findings highlight the prospects for the composite of WS2 towards the improvement of bone regeneration applications.