Search

The effective conversion of carbon dioxide (CO2) into valuable chemical fuels relies significantly on the donation of multiple electrons. Its efficiency is closely linked to both the density and lifetime of excited charge carriers. In this study, a hybrid catalyst system comprising covalently bonded InP/ZnS quantum dots (QDs) and Re‐complexes is showcased. The electronic band alignment between the QDs and the Re‐complexes is revealed to dominate the multi‐electron transfer process for photocatalytic conversion to methane (CH4). Notably, the size of the QDs is found to be a determining parameter. Among the three QD sizes investigated, transient absorption spectroscopy studies unveil that rapid multi‐electron transfer from the QDs to the Re‐catalyst occurs in smaller QDs (2.3 nm) due to the substantial driving force. Consequently, the photocatalytic conversion of CO2 to CH4 is significantly enhanced with a turnover number of 6, corresponding to the overall apparent quantum yield of ≈1%. This research underscores the possibilities of engineering multi‐electron transfer by manipulating the electronic band alignment within a catalytic system. This can serve as a guide for optimizing photocatalytic CO2 reduction. [ABSTRACT FROM AUTHOR]

Adult body mass is largely related to nutrition levels, which can be affected by external stressors, such as diet, environment, and disease. High‐status and low‐status groups likely had very different nutrition and stress experiences, which might result in differences in population's body mass. Since inequality between social statuses prevailed in Europe in the post‐Medieval period, did these differences result in body mass variations between high‐status and low‐status populations in the Netherlands? In order to answer this question, this research compared body size of two post‐Medieval urban skeletal collections with different social statuses from the Eusebius cemetery of two cemeteries of the 17th–19th centuries: the Arnhem and the Broerenkerk church of Zwolle, the Netherlands. Social statuses of the two collections are estimated based on the burial locations, grave goods, and historical records. Body mass was estimated using both femoral head diameter method and stature/bi‐iliac breadth method. Results have shown no statistically significant differences in body mass between the two samples. Therefore, this research suggests that inequality in post‐Medieval Dutch society did not result in observable population body mass differences in the skeletal collections of different social status groups. It cannot, however, prove that social inequality in populations did not impact body size or health more broadly. [ABSTRACT FROM AUTHOR]

The weak dielectric screening in 2D semiconducting transition metal dichalcogenides give rise to strongly bound quasiparticles, which provides a platform to investigate the diverse excitonic phenomena and correlated physics. However, how to effectively control these quasiparticles is still a challenge for their applications in optoelectronic and valleytronic devices. Herein, by means of fabricating monolayer WSe2 and transition metal oxide (TMO) heterostructures, polaronic trion, that is a trion dressed with soft rotational optical (RO) phonons, is realized due to the strong interfacial coupling. This Fröhlich bound state of trion dramatically increases the trion binding energy (BE) from room temperature to 65 meV at 80 K in WSe2/LaAlO3 (LAO). However, the increase of the trion BE for WSe2/SrTiO3 (STO) occurs below the phase transition temperature. This work expands the possibilities of the TMDs/TMOs heterostructures and promotes the development of 2D van der Waals materials for quasiparticle‐based devices. [ABSTRACT FROM AUTHOR]

Recently, research on the edge states of 2D lead halide perovskites (LHPs) has been attracting much attention. The lower‐energy edge state (LES) is believed to provide an efficient pathway for the dissociation of photoexcited excitons. However, the mechanism of the LES formation remains controversial, and studies that establish precisely the local electronic properties are lacking. Herein, the first study of spatially resolved electronic structures in 2D LHP single‐crystal flakes by X‐ray photoemission electron microscopy is presented, specifically identifying the contribution from the edge area. The results show that blueshifts occur in the Pb 5d core‐level peaks at the edge area compared to the interior area with much less difference in I 4d core‐level peaks. The shift becomes more pronounced as n varies from 1 to 3 (≈0.2–1.0 eV). This phenomenon is attributed to the surface restructuring of the edge area induced by the release of mechanical strain through lattice expansion. This work provides an important reference on the origin of the LES of 2D LHPs and is beneficial for future optoelectronic device applications. [ABSTRACT FROM AUTHOR]

Using heterogeneous photocatalysts for harvesting sunlight and converting it for water remediation and splitting are promising to mitigate the possible crisis of environment and energy. Among various composites, the MoS2‐based heterostructures and Ni‐based systems exhibit unique electronic, optical properties and redox capabilities, enabling their roles as photocatalysts. Herein, the impacts of chemical environments on the Ni electronic structures within the MoS2‐Ag‐Ni ternary systems are studied via X‐ray photoemission electron spectroscopy (X‐PEEM). Ni nanoparticles with two different sizes of 70 and 200 nm were loaded to MoS2 flakes with silver buffers as bridges. Heterostructures with a nominal mol percentage of (MoS2)77Ag3.7Ni19.3 were synthesized through an ultrasound‐assisted wet method. The oxidation states and various interfacial interactions of Ni with MoS2 in MoS2‐Ag‐Ni ternary composite are spectromicroscopically determined, combining the X‐ray absorption spectroscopy near Ni L‐edges and the imaging capability of the X‐PEEM. Results showed that Ni mainly retrains its chemical states of metal and native oxidizations without observable electronic features subjected to bonding with the sulfur from the MoS2 flakes. The charge migration channel set up by the Ag buffer thus contributes to electron–hole migrations that facilitate the photocatalytic performance of the ternary system eventually. [ABSTRACT FROM AUTHOR]

Structured Silicon Carbide was proposed to be an ideal template for the production of arrays of edge specific graphene nanoribbons (GNRs), which could be used as a base material for graphene transistors. We prepared periodic arrays of nanoscaled stripe-mesas on SiC surfaces using electron beam lithography and reactive ion etching. Subsequent epitaxial graphene growth by annealing is differentiated between the basal-plane mesas and the faceting stripe walls as monitored by means of atomic force microscopy (AFM). Microscopic low energy electron diffraction (μ-LEED) revealed that the graphene ribbons on the facetted mesa side walls grow in epitaxial relation to the basal-plane graphene with an armchair orientation at the facet edges. The π-band system of the ribbons exhibits linear bands with a Dirac like shape corresponding to monolayer graphene as identified by angle-resolved photoemission spectroscopy (ARPES). [ABSTRACT FROM AUTHOR]