DJL

Reconstructing canonical binary compounds by inserting a third agent can significantly modify their electronic and phonon structures. Therefore, it has inspired the semiconductor communities in various fields. Introducing this paradigm will potentially revolutionize thermoelectrics as well. Using a solution synthesis, Bi₂S₃ was rebuilt by adding disordered Bi and weakly bonded I. These new structural motifs and the altered crystal symmetry induce prominent changes in electrical and thermal transport, resulting in a great enhancement of the figure of merit. The as-obtained nanostructured Bi₁₃S₁₈I₂ is the first non-toxic, cost-efficient, and solution-processable n-type material with z T=1.0.

Bi₂S₃ was rebuilt by adding disordered Bi and weakly bonded I in a solution synthesis. The new structural motifs and the altered crystal symmetry induce prominent changes in electrical and thermal transport. The as-obtained nanostructured Bi₁₃S₁₈I₂ is a non-toxic, cost-efficient, and solution-processable n-type thermoelectric material with z T=1.0.

Controlling the selectivity in electrochemical CO₂ reduction is an unsolved challenge. While tin (Sn) has emerged as a promising non-precious catalyst for CO₂ electroreduction, most Sn-based catalysts produce formate as the major product, which is less desirable than CO in terms of separation and further use. Tin monoxide (SnO) nanoparticles supported on carbon black were synthesized and assembled and their application in CO₂ reduction was studied. Remarkably high selectivity and partial current densities for CO formation were obtained using these SnO nanoparticles compared to other Sn catalysts. The high activity is attributed to the ultra-small size of the nanoparticles (2.6 nm), while the high selectivity is attributed to a local pH effect arising from the dense packing of nanoparticles in the conductive carbon black matrix.

SnO NPs (tin monoxide nanoparticles) supported on carbon black were synthesized and their use in CO₂ reduction was studied. High partial current densities for CO formation were obtained using these NPs compared to other Sn catalysts. The high activity is attributed to the ultra-small size of the nanoparticles (2.6 nm). The high selectivity is attributed to a pH effect arising from dense packing of NPs in the conductive carbon black matrix.

Using curiosity as the starting point for careful observation of nature and society is a nontrivial skill, and a starting point for new intellectual endeavors and adventures. It is one essential contributor to creativity in science, and a start in forcing new ideas into inflexible professional orthodoxies.

Glass distillation equipment from an early modern alchemical laboratory was analyzed for its technology of manufacture and potential origin. Chemical data show that the assemblage can be divided into sodium-rich, colorless distillation vessels made with glass from Venice or its European imitation, and potassium-rich dark-brown non-specialized forms produced within the technological tradition of forest glass typical for central and north-western Europe. These results complete our understanding of the supply of technical apparatus at one of the best-preserved alchemical laboratories and highlight an early awareness of the need for high-quality instruments to guarantee the successful outcome of specialized chemical operations. This study demonstrates the potential of archaeological science to inform historical research around the practice of early chemistry and the development of modern science.

What sort of operations did alchemists carry out in their laboratories? What tools did they use? Can answering similar questions help us better understand the development of science and technology in the Renaissance? It is shown that the information gained through archaeometric analysis of artefacts from laboratories can be a powerful tool in exploring how alchemy was practiced in early modern Europe.

All-inorganic perovskite solar cells with high efficiency and improved stability are promising for commercialization. A multistep solution-processing method was developed to fabricate high-purity inorganic CsPbBr₃ perovskite films for use in efficient solar cells. By tuning the number of deposition cycles (n) of a CsBr solution, the phase conversion from CsPb₂Br₅ (n ≤3), to CsPbBr₃ (n=4), and Cs₄PbBr₆ (n≥5) was optimized to achieve vertical- and monolayer-aligned grains. Upon interfacial modification with graphene quantum dots, the all-inorganic perovskite solar cell (without a hole-transporting layer) achieved a power conversion efficiency (PCE) as high as 9.72 % under standard solar illumination conditions. Under challenging conditions, such as 90 % relative humidity (RH) at 25 °C or 80 °C at zero humidity, the optimized device retained 87 % PCE over 130 days or 95 % over 40 days, compared to the initial efficiency.

All-inorganic perovskite films were fabricated by a multistep solution-processed deposition strategy, in which a phase conversion from CsPb₂Br₅ to CsPbBr₃ and then to Cs₄PbBr₆ was achieved upon increasing deposition cycles of a cesium bromide solution. A power conversion efficiency up to 9.72 % was obtained from the CsPbBr₃ solar cells, which are free of hole-transporting layers.

Spontaneously solar-driven water splitting into H₂ and O₂, that is, the conversion of solar energy to chemical energy is intensively being investigated. In their Communication (DOI: 10.1002/anie.201711357), M. Fujitsuka, T. Majima et al. present a new 2D heterostructure of black phosphorus and bismuth vanadate for photocatalytic water splitting without any sacrificial agents under visible light irradiation. The Z-scheme architectural band structures contribute to an effective charge separation.

The size-tunable emission of luminescent quantum dots (QDs) makes them highly interesting for applications that range from bioimaging to optoelectronics. For the same applications, engineering their luminescence lifetime, in particular, making it longer, would be as important; however, no rational approach to reach this goal is available to date. We describe a strategy to prolong the emission lifetime of QDs through electronic energy shuttling to the triplet excited state of a surface-bound molecular chromophore. To implement this idea, we made CdSe QDs of different sizes and carried out self-assembly with a pyrene derivative. We observed that the conjugates exhibit delayed luminescence, with emission decays that are prolonged by more than 3 orders of magnitude (lifetimes up to 330 μs) compared to the parent CdSe QDs. The mechanism invokes unprecedented reversible quantum dot to organic chromophore electronic energy transfer.

Extended play: The first examples of delayed luminescence involving CdSe quantum dots are reported, with by emission decays that are prolonged by more than 3 orders of magnitude (lifetimes up to 330 μs) compared to analogous parent compounds. The mechanism involves unprecedented reversible quantum dot to organic chromophore electronic energy transfer.

Fluorescent probes in the second near-infrared window (NIR-II) allow high-resolution bioimaging with deep-tissue penetration. However, existing NIR-II materials often have poor signal-to-background ratios because of the lack of target specificity. Herein, an activatable NIR-II nanoprobe for visualizing colorectal cancers was devised. This designed probe displays H₂S-activated ratiometric fluorescence and light-up NIR-II emission at 900–1300 nm. By using this activatable and target specific probe for deep-tissue imaging of H₂S-rich colon cancer cells, accurate identification of colorectal tumors in animal models were performed. It is anticipated that the development of activatable NIR-II probes will find widespread applications in biological and clinical systems.

NIR-II emission: Activatable nanoprobes with second near-infrared emissions were constructed. The designed probes displayed H₂S-activated ratiometric fluorescence and light-up NIR-II emission and were applied to the specific imaging of H₂S-rich colon tumors and differentiation of cancer type.

Smart polymeric materials that autonomously indicate mechanically damaged areas are developed by N. R. Sottos and co-workers, as described on page 2189. Microcapsules containing the color-changing indicator are homogeneously dispersed in a polymer matrix. Mechanical damage (e.g., scratch, abrasion, or compression) causes the microcapsules to rupture and release the core materials. A dramatic color change is initiated immediately to highlight the damaged regions.

Large scale synthesis and delamination of 2D Mo₂CT _x (where T is a surface termination group) has been achieved by selectively etching gallium from the recently discovered nanolaminated, ternary transition metal carbide Mo₂Ga₂C. Different synthesis and delamination routes result in different flake morphologies. The resistivity of free-standing Mo₂CT _x films increases by an order of magnitude as the temperature is reduced from 300 to 10 K, suggesting semiconductor-like behavior of this MXene, in contrast to Ti₃C₂T _x which exhibits metallic behavior. At 10 K, the magnetoresistance is positive. Additionally, changes in electronic transport are observed upon annealing of the films. When 2 μm thick films are tested as electrodes in supercapacitors, capacitances as high as 700 F cm⁻³ in a 1 m sulfuric acid electrolyte and high capacity retention for at least 10,000 cycles at 10 A g⁻¹ are obtained. Free-standing Mo₂CT _x films, with ≈8 wt% carbon nanotubes, perform well when tested as an electrode material for Li-ions, especially at high rates. At 20 and 131 C cycling rates, stable reversible capacities of 250 and 76 mAh g⁻¹, respectively, are achieved for over 1000 cycles.

2D Mo₂C (MXene) is produced using different synthesis routes, which lead to different flake morphologies. Mo₂C exhibits a semiconductor-like increase in resistivity from 300 to 10 K. Mo₂C electrodes in a supercapacitor achieve 700 F cm⁻³ capacitance in 1 m H₂SO₄ for 10,000 cycles. Mo₂C–Carbon nano tube (CNT) electrodes possess 250 mAh g⁻¹ capacity for 1000 cycles, showing promise as anode for batteries and Li-ion capacitors.