Structure and magnetic properties of the maple leaf antiferromagnet Ho3ScO6

Ho3ScO6 harbors a frustrated maple leaf lattice MLL . It crystalizes in the Mg3TeO6 type structure and has a centrosymmetric trigonal space group R3 . This system contains stacked layers of magnetic rings along the c axis consisting of six magnetic Ho3 ions forming Ho hexagons, which are connected into a two dimensional network by equilateral and isosceles triangles to form a rare example of a MLL. Long range magnetic order is reached below TN 4.1 K with a 120 amp; 9702; spin arrangement on the equilateral triangles, resulting in a positive vector chirality ground state configuratio

Stimuli Responsive Electronic Reconfiguration in Benzo ghi perylene TCNQ Donor Acceptor Crystalline Networks

Template assisted crystal engineering provides a powerful strategy for constructing ordered networks tailored to organic electronic applications. We introduce a solution based strategy to fabricate crystalline needle like arrays of charge transfer complexes CTCs between electron donating benzo ghi perylene BP and electron accepting TCNQ. Well defined square crystals of BP polymorphs were employed as templates for the spatially controlled anisotropic growth of CTC needle like arrays. By tuning concentration and deposition rates, we modulated BP crystal dimensions and hence controlled the growth of needle networks mimicking the template spatial scale. In solution, these free standing flexible meshes were detached from the BPs and redeposited onto variable substrates, while the BP templates remain undissolved, enabling repeated fabrication cycles. CTC formation induces an electronic redistribution with thermally reversible modulation of characteristic electronic states. Such transformation modifies the BP luminescence character while bare BP exhibits a strong green emission, it is quenched in the presence of TCNQ and replaced by a weaker blueish CTC emission, establishing a charge transfer mediated photonic response. Our study provides a combination of crystal engineering with microspectroscopic insights offering a highly sensitive handle for elucidating charge redistribution and modulation of electronic states in CTC upon external stimul

Surface Deposition of Dome Shaped Metal Organic Complexes A New Approach to the Generation of Single Site Catalysts

A novel approach combining the advantages of heterogeneous with those of homogeneous catalysis is the deposition of metal organic complexes on a metallic surface to create well defined single site catalysts. Dome shaped organometallic complexes with weakly binding coligands are well suited for this purpose. With this in mind, a new dithia [2.1.1] 2,6 pyridinophane ligand has been synthesized. The corresponding molybdenum 0 tricarbonyl complex is structurally and spectroscopically characterized in the bulk and in homogeneous solution. Monolayers of this complex are deposited on Au 111 and investigated with the help of surface spectroscopy infrared reflection absorption spectroscopy, X ray photoelectron spectroscopy, and near edge X ray absorption fine structure . These methods indicate a slightly tilted orientation of the complex on the gold surface, which is confirmed by density functional theory DFT calculations. The reactivity of the complex toward dioxygen is evaluated and compared to analogous complexes supported by aza and thiacalix[3] 2,6 pyridine ligand

In situ UV Vis absorption spectroscopy study of the water electrooxidation on cobalt oxide catalysts

Despite the current prominence of cobalt oxides as electrocatalysts for the alkaline oxygen evolution reaction OER , there is a lack of unambiguous demonstration for the presence and the role of Co4 prior to during the OER. Here, we combine electrochemistry with in situ UV Vis absorption spectroscopy to investigate and discuss the previously unaddressed effect of different OH amp; 8722; concentrations in the range from 1 M to 0.016 M on the population of Co4 in thin films of CoOx and its concomitant impact on their OER performance. Evidence for Co4 is provided by in situ X ray absorption spectroscopy. Our UV Vis absorption spectroscopic findings indicate that, not only can the overall redox conversion of Co be qualitatively monitored as a function of potential and OH amp; 8722; concentration, but also the formation of oxidized Co i.e.,Co3 and Co4 assigned to a peak at 800 nm can be more quantitatively tracked in situ via stepped potential spectroelectrochemistry; with their optical signals becoming stronger at higher OH amp; 8722; concentrations above 1.2 V vs. RHE, which is consistent with voltammetric redox couples, indicating an enhancement in Co oxidation state and the consequent predominance of Co4 under conditions of elevated OH amp; 8722; concentrations. Furthermore, the evolved oxygen due to OER does not depend on Co4 or OH amp; 8722; activity at 1.54 V vs. RHE, while a correlation with both Co4 and OH amp; 8722; is identified at 1.59 V vs. RHE. This study not only provides spectral insight into the redox chemistry of Co at OER relevant potentials but also highlights the importance of Co4 in facilitating the alkaline OER at high OH amp; 8722; concentrations and current densitie

Printing of tin perovskite solar cells via controlled crystallization

The urgent need for sustainable electricity has driven progress in solar technologies, with perovskite photovoltaics standing out as a top contender. However, the presence of toxic lead in current perovskite devices necessitates the exploration of alternative materials. This study addresses the challenges associated with tin perovskite fabrication and the industrial scale up of this lead free technology. It introduces a new approach to regulate the key process of crystallization, involving a combination of new additives and a gas pulse to trigger and subsequently control nucleation and crystal growth. In situ optical spectroscopy probed the crystallization and enabled the optimization of the printing conditions. Solar cells were fabricated with a power conversion efficiency of 5.38 for 0.1 cm2, 4.02 for 1 cm2 and 2.31 for 5 cm2 devices. They were tested under indoor lighting conditions and functioned at similar efficiency levels, thereby demonstrating the potential of this technology for commercial applications. Our new crystallization control method for printing Sn perovskites enabled the fabrication of the first Sn based solar cell via slot die coating, which is ideally suited for roll to roll manufacturing. This innovation opens new avenues for the development of fully printed lead free perovskite photovoltaics, contributing significantly to the advancement of sustainable energy technologie

Controlled Formation of Skyrmion Bags

Topologically non trivial magnetic solitons are complex spin textures with a distinct single particle nature. Although magnetic skyrmions, especially those with unity topological charge, have attracted substantial interest due to their potential applications, more complex topological textures remain largely theoretical. In this work, the stabilization of isolated higher order skyrmion bags beyond the prototypical amp; 960; skyrmion in ferromagnetic thin films is experimentally demonstrate, which has posed considerable challenges to date. Specifically, controlled generation of skyrmionium 2 amp; 960; skyrmion , target skyrmion 3 amp; 960; skyrmion , and skyrmion bags with variable topological charge are achieved through the introduction of artificially engineered anisotropy defects via local ion irradiation. They act as preferential sites for the field or laser induced nucleation of skyrmion bags. Remarkably, ultrafast laser pulses achieve a substantially higher conversion rate transforming skyrmions into higher order skyrmion bags compared to their formation driven by magnetic fields. High resolution x ray imaging enables direct observation of the resulting skyrmion bags. Complementary micromagnetic simulations reveal the pivotal role of defect geometry particularly diameter in stabilizing closed loop domain textures. The findings not only broaden the experimental horizon for skyrmion research, but also suggest strategies for exploiting complex topological spin textures within a unified material platform for practical application

Size and Surface Effects in the Ultrafast Dynamics of Strongly Cooperative Spin Crossover Nanoparticles

Cooperative photoinduced switching of molecular materials at the nanoscale is still in its infancy. Strongly cooperative spin crossover nanomaterials are arguably the best prototypes of photomagnetic and volume changing materials that can be manipulated by short pulses of light. Open questions remain regarding their non equilibrium dynamics upon light excitation and the role of cooperative elastic interactions in nanoscale systems that are characterized by large surface volume ratios. Femtosecond resolved broadband spectroscopy is performed on nanorods of the strongly cooperative Fe triazole, which undergoes a reversible low spin to high spin HS phase transition amp; 8776;360 K. Supported by density functional theory and mechano elastic Monte Carlo simulations, a marked difference is observed in the photoswitching dynamics at the surface of the nanoparticles compared with the core. Surprisingly, under low excitation lt;2 conditions, there occurs a transient increase in the HS population at the surface on the picosecond time scale, while the HS population in the core decays concomitantly. These results shed light onto the importance of surface properties and dynamical size limits of nanoscale photoresponsive nanomaterials that can be used in a broad range of application

Structural Modulation of Nanographenes Enabled by Defects, Size and Doping for Oxygen Reduction Reaction

Nanographenes are among the fastest growing materials used for the oxygen reduction reaction ORR thanks to their low cost, environmental friendliness, excellent electrical conductivity, and scalable synthesis. The perspective of replacing precious metal based electrocatalysts with functionalized graphene is highly desirable for reducing costs in energy conversion and storage systems. Generally, the enhanced ORR activity of the nanographenes is typically deemed to originate from the heteroatom doping effect, size effect, defects effect, and or their synergistic effect. All these factors can efficiently modify the charge distribution on the sp2 conjugated carbon framework, bringing about optimized intermediate adsorption and accelerated electron transfer steps during ORR. In this review, the fundamental chemical and physical properties of nanographenes are first discussed about ORR applications. Afterward, the role of doping, size, defects, and their combined influence in boosting nanographenes ORR performance is introduced. Finally, significant challenges and essential perspectives of nanographenes as advanced ORR electrocatalysts are highlighte

High Temperature Growth of CeOx on Au 111 and Behavior under Reducing and Oxidizing Condition

Inverse oxide metal model catalysts can show superior activity and selectivity compared with the traditional supported metal oxide architecture, commonly attributed to the synergistic overlayer support interaction. We have investigated the growth and redox properties of ceria nanoislands grown on Au 111 between 700 and 890 C, which yields the CeO2 Au 111 model catalyst system. We have observed a distinct correlation between deposition temperature, structural order, and oxide composition through low energy electron microscopy, low energy electron diffraction, intensity voltage curves, and X ray absorption spectroscopy. Improved structural order and thermal stability of the oxide have been achieved by increasing the oxygen chemical potential at the substrate surface using reactive oxygen O O2 instead of molecular O2 during growth. In situ characterization under reducing H2 and oxidizing atmospheres O2, CO2 indicates an irreversible loss of structural order and redox activity at high reduction temperatures, while moderate temperatures result in partial decomposition of the ceria nanoislands Ce3 Ce4 to metallic cerium Ce0 . The weak interaction between Au 111 and CeOx would facilitate its reduction to the Ce0 metallic state, especially considering the comparatively strong interaction between Ce0 and Au0. Besides, the higher reactivity of atomic oxygen promotes a stronger interaction between the gold and oxide islands during the nucleation process, explaining the improved stability. Thus, we propose that by driving the nucleation and growth of the ceria Au system in a highly oxidizing regime, novel chemical properties can be obtaine

Spatial distribution and stability of Gd0.6Eu0.4VO4 nanoparticles injected in mouse ear pinnae

X Ray Fluorescence XRF mapping is employed for the study of the spatial distribution of GdVO4 Eu nanoparticles NPs after their injection into mouse ear pinnae. The injected NP colloids were detectable in a concentration range from 5 to 30 mM in vanadate ions 90 530 nM in NP concentrations . The distribution maps were recorded separately for Gd, Eu, and V and reveal that the three elements are collocalized, indicating the NP stability after the injection. The distribution pattern of the NPs is not homogeneous; they follow bifurcated paths of easy flow demonstrating the complexity of the tissue colloid interactions. The V K, Gd L3 and Eu L3 edge X ray Absorption Fine Structure XAFS spectra of the NPs recorded prior to and after their injection confirm that the integrity of the nanoparticles is preserved after injection. This combined XRF XAFS analysis paves the way for studies on the long term fate of injected Gd containing NPs in tissue