Ruddlesden-Popper Phase in Two-Dimensional Inorganic Halide Perovskites: A Plausible Model and the Supporting Observations.

A Ruddlesden-Popper (RP) type structure is well-known in oxide perovskites and is related to many interesting properties such as superconductivity and ferroelectricity. However, the RP phase has not yet been discovered in inorganic halide perovskites. Here, we report the direct observation of unusual structure in two-dimensional CsPbBr3 nanosheets which could be interpreted as the RP phase based on model simulations. Structural details of the plausible RP domains and domain boundaries between the RP and conventional perovskite phases have been revealed on the atomic level using aberration-corrected scanning transmission electron microscopy. The finding marks a major advance toward future inorganic halide RP phase synthesis and theoretical modeling, as well as unraveling their structure-property relationship

Solar-driven carbon dioxide fixation using photosynthetic semiconductor bio-hybrids.

Solar-driven conversion of carbon dioxide to value-added carbon products is an ambitious objective of ongoing research efforts. However, high overpotential, low selectivity and poor CO2 mass transfer plague purely inorganic electrocatalysts. In this instance, we can consider a class of biological organisms that have evolved to achieve CO2 fixation. We can harness and combine the streamlined CO2 fixation pathways of these whole organisms with the exceptional ability of semiconducting nanomaterials to harvest solar energy. A novel nanomaterial-biological interface has been pioneered in which light-capturing cadmium sulfide nanoparticles reside within individual organisms essentially powering biological CO2 fixation by solar energy. In order to further develop the photosensitized organism platform, more biocompatible photosensitizers and cytoprotective strategies are required as well as elucidation of charge transfer mechanisms. Here, we discuss the ability of gold nanoclusters to photosensitize a model acetogen effectively and biocompatibly. Additionally, we present innovative materials including two-dimensional metal organic framework sheets and alginate hydrogels to shield photosensitized cells. Finally, we delve into original work using transient absorption spectroscopy to inform on charge transfer mechanisms

Influence mechanism between information management technologies and green innovation: the role of sustainable firms practices in China

Despite the proposition of sustainable development goals by the United Nations, the progress shown by the organizations is not satisfactory. It also raised the attention of the policymakers to overcome those challenges by identifying potential solutions. Hence, the current study aims to assess the role of the information and knowledge management process in attaining green innovation in sustainable practices. For this purpose, the data is collected from the 395 organizations operating in China that are ISO 14001 certified. The application of PLS-SEM shows that information and knowledge management significantly and positively enhance all three sustainable practices, which eventually play an encouraging role in green innovation. Additionally, all three types of sustainable practices also reported mediating the relationships between the information and knowledge management process and green innovation. Based on the findings, organizations are recommended to integrate and align sustainable practices, information management, and green innovation with the mission, vision, and routine activities and objectives

Environmental investigation of bio-modification of steel slag through microbially induced carbonate precipitation

Steel slag (SS) is one of byproduct of steel manufacture industry. The environmental concerns of SS may limit their re-use in different applications. The goal of this study was to investigate the leaching behavior of metals from SS before and after treated by microbially induced carbonate precipitation (MICP). Toxicity characteristic leaching procedure, synthetic precipitation leaching procedure and water leaching tests were performed to evaluate the leaching behavior of major elements (Fe, Mg and Ca) and trace elements (Ba, Cu and Mn) in three scenarios. The concentrations of leaching metals increased with the content of SS. After it reached the peak concentration, the leaching concentration decreased with the content of SS. The leachability of all elements concerned in this study was below 0.5%. The carbonate generated from the MICP process contributed to the low leachability of metals. After bio-modified by MICP process, the leaching concentrations of Ba from TCLP, SPLP and WLT tests were below 2.0 mg/L, which was the limit in drinking water regulated by U.S. EPA. The concentrations of Cu leached out from MICP-treated SS-sand samples were below 1.3 mg/L which is the limit regulated by national secondary drinking water. Compared with the regulations of U.S.EPA and Mississippi Department of Environment Quality (MDEQ), MICP-treated samples were classified as non-hazardous materials with respects to the leaching of metals. Meanwhile, maximum contaminant limits regulated by U.S.EPA states that MICP-treated SS are eco-friendly materials that can be reused as construction materials

Bacteria photosensitized by intracellular gold nanoclusters for solar fuel production.

The demand for renewable and sustainable fuel has prompted the rapid development of advanced nanotechnologies to effectively harness solar power. The construction of photosynthetic biohybrid systems (PBSs) aims to link preassembled biosynthetic pathways with inorganic light absorbers. This strategy inherits both the high light-harvesting efficiency of solid-state semiconductors and the superior catalytic performance of whole-cell microorganisms. Here, we introduce an intracellular, biocompatible light absorber, in the form of gold nanoclusters (AuNCs), to circumvent the sluggish kinetics of electron transfer for existing PBSs. Translocation of these AuNCs into non-photosynthetic bacteria enables photosynthesis of acetic acid from CO2. The AuNCs also serve as inhibitors of reactive oxygen species (ROS) to maintain high bacterium viability. With the dual advantages of light absorption and biocompatibility, this new generation of PBS can efficiently harvest sunlight and transfer photogenerated electrons to cellular metabolism, realizing CO2 fixation continuously over several days

Cytoprotective metal-organic frameworks for anaerobic bacteria.

We report a strategy to uniformly wrap Morella thermoacetica bacteria with a metal-organic framework (MOF) monolayer of nanometer thickness for cytoprotection in artificial photosynthesis. The catalytic activity of the MOF enclosure toward decomposition of reactive oxygen species (ROS) reduces the death of strictly anaerobic bacteria by fivefold in the presence of 21% O2, and enables the cytoprotected bacteria to continuously produce acetate from CO2 fixation under oxidative stress. The high definition of the MOF-bacteria interface involving direct bonding between phosphate units on the cell surface and zirconium clusters on MOF monolayer, provides for enhancement of life throughout reproduction. The dynamic nature of the MOF wrapping allows for cell elongation and separation, including spontaneous covering of the newly grown cell surface. The open-metal sites on the zirconium clusters lead to 600 times more efficient ROS decomposition compared with zirconia nanoparticles

Evolution of Interlayer Coupling in Twisted MoS2 Bilayers

Van der Waals (vdW) coupling is emerging as a powerful method to engineer and tailor physical properties of atomically thin two-dimensional (2D) materials. In graphene/graphene and graphene/boron-nitride structures it leads to interesting physical phenomena ranging from new van Hove singularities1-4 and Fermi velocity renormalization5, 6 to unconventional quantum Hall effects7 and Hofstadter's butterfly pattern8-12. 2D transition metal dichalcogenides (TMDCs), another system of predominantly vdW-coupled atomically thin layers13, 14, can also exhibit interesting but different coupling phenomena because TMDCs can be direct or indirect bandgap semiconductors15, 16. Here, we present the first study on the evolution of interlayer coupling with twist angles in as-grown MoS2 bilayers. We find that an indirect bandgap emerges in bilayers with any stacking configuration, but the bandgap size varies appreciably with the twist angle: it shows the largest redshift for AA- and AB-stacked bilayers, and a significantly smaller but constant redshift for all other twist angles. The vibration frequency of the out-of-plane phonon in MoS2 shows similar twist angle dependence. Our observations, together with ab initio calculations, reveal that this evolution of interlayer coupling originates from the repulsive steric effects, which leads to different interlayer separations between the two MoS2 layers in different stacking configurations

Life Cycle Analysis on Fossil Energy Ratio of Algal Biodiesel: Effects of Nitrogen Deficiency and Oil Extraction Technology

Life cycle assessment (LCA) has been widely used to analyze various pathways of biofuel preparation from “cradle to grave.” Effects of nitrogen supply for algae cultivation and technology of algal oil extraction on life cycle fossil energy ratio of biodiesel are assessed in this study. Life cycle fossil energy ratio of Chlorella vulgaris based biodiesel is improved by growing algae under nitrogen-limited conditions, while the life cycle fossil energy ratio of biodiesel production from Phaeodactylum tricornutum grown with nitrogen deprivation decreases. Compared to extraction of oil from dried algae, extraction of lipid from wet algae with subcritical cosolvents achieves a 43.83% improvement in fossil energy ratio of algal biodiesel when oilcake drying is not considered. The outcome for sensitivity analysis indicates that the algal oil conversion rate and energy content of algae are found to have the greatest effects on the LCA results of algal biodiesel production, followed by utilization ratio of algal residue, energy demand for algae drying, capacity of water mixing, and productivity of algae

Giant Light-Emission Enhancement in Lead Halide Perovskites by Surface Oxygen Passivation.

Surface condition plays an important role in the optical performance of semiconductor materials. As new types of semiconductors, the emerging metal-halide perovskites are promising for next-generation optoelectronic devices. We discover significantly improved light-emission efficiencies in lead halide perovskites due to surface oxygen passivation. The enhancement manifests close to 3 orders of magnitude as the perovskite dimensions decrease to the nanoscale, improving external quantum efficiencies from <0.02% to over 12%. Along with about a 4-fold increase in spontaneous carrier recombination lifetimes, we show that oxygen exposure enhances light emission by reducing the nonradiative recombination channel. Supported by X-ray surface characterization and theoretical modeling, we propose that excess lead atoms on the perovskite surface create deep-level trap states that can be passivated by oxygen adsorption