Two-dimensional Molecular Phase Transition of Alkylated-TDPB on Au(111) and Cu(111) Surfaces

The derivatives of aromatic cores bearing alkyl chains with different lengths are of potential interest in on-surface chemistry, and thus have been widely investigated both at liquid-solid interfaces and in vacuum. Here, we report on the structural evaluation of self-assembled 1,3,5-tri(4-dodecylphenyl)benzene(TDPB) molecules with increased molecular coverages on both Au(111) and Cu(111) surfaces. As observed on Au(111), rhombic and herringbone structures emerge successively depending on surface coverage. In the case of Cu(111), the same process of phase conversion is also observed, but with two distinct structures. In comparison, the self-assembled structures on Au(111) surface are packed more densely than that on Cu(111) surface under the same preparation conditions. This may fundamentally result from the higher adsorption energy of TDPB molecules on Cu(111), restricting their adjustment to optimize a thermodynamically favorable molecular packing.     

Additive manufacturing for energy storage: Methods,designs and material selection for customizable 3D printed batteries and supercapacitors

Additive manufacturing and 3D printing in particular have the potential to revolutionize existing fabrication processes, where objects with complex structures and shapes can be built with multifunctional material systems. For electrochemical energy storage devices such as batteries and supercapacitors, 3D printing methods allows alternative form factors to be conceived based on the end use application need in mind at the design stage. Additively manufactured energy storage devices require active materials and composites that are printable, and this is influenced by performance requirements and the basic electrochemistry. The interplay between electrochemical response, stability, material type, object complexity and end use application are key to realising 3D printing for electrochemical energy storage. Here, we summarise recent advances and highlight the important role of methods, designs and material selection for energy storage devices made by 3D printing, which is general to the majority of methods in use currently.     

Demystifying terms for understanding bioelectrochemical systems towards sustainable wastewater treatment

Bioelectrochemical systems (BESs) have been intensively studied in the past decade, but precise understanding of BESs performance is hindered by unclear definition of several key parameters. Herein, we analyze and discuss three sets of terms about conversion efficiency, energy performance, and pilot scale. It is suggested that ‘Coulombic recovery’ can avoid the misleading results because of different organic removals, compared with ‘Coulombic efficiency.’ Power density is not a suitable term to describe energy performance of BESs, and energy production/consumption should be reported in the energy unit such as kWh. Pilot-scale BESs should meet several criteria, including hydraulic capacity, use of actual wastewater, non-laboratory condition, and long-term operation. Proper use of those terms is strongly encouraged and will be critically important to BESs research and development.     

Reducing Detrimental Defects for High‐Performance Metal Halide Perovskite Solar Cells

In several photovoltaic (PV) technologies, the presence of electronic defects within the semiconductor band gap limit the efficiency, reproducibility, as well as lifetime. Metal halide perovskites (MHPs) have drawn great attention because of their excellent photovoltaic properties that can be achieved even without a very strict film‐growth control processing. Much has been done theoretically in describing the different point defects in MHPs. Herein, we discuss the experimental challenges in thoroughly characterizing the defects in MHPs such as, experimental assignment of the type of defects, defects densities, and the energy positions within the band gap induced by these defects. The second topic of this Review is passivation strategies. Based on a literature survey, the different types of defects that are important to consider and need to be minimized are examined. A complete fundamental understanding of defect nature in MHPs is needed to further improve their optoelectronic functionalities.     

Supramolecular Photothermal Effects: A Promising Mechanism for Efficient Thermal Conversion

Supramolecular assemblies have been very successful in regulating the photothermal conversion efficiency of organic photothermal materials in a simple and flexible way, compared with conventional molecular synthesis. In these assemblies, it is the inherent physiochemical mechanism that determines the photothermal conversion, rather than the assembly strategy. This Minireview summarizes supramolecular photothermal effects, which refer to the unique features of supramolecular chemistry for regulating the photothermal conversion efficiency. Emphasis is placed on the mechanisms of how self‐assembly affects the photothermal performance. The supramolecular photothermal effects on various types of light‐harvesting species are discussed in detail. The timely interpretation of supramolecular photothermal effects is promising for the future design of the photothermal materials with high efficiency, precision, and multiple functionalities for a wide array of applications.     

Preferential Formation of Mono‐Metallofullerenes Governed by the Encapsulation Energy of the Metal Elements: A Case Study on Eu@C2n (2n=74–84) Revealing a General Rule

Encapsulating one to three metal atoms or a metallic cluster inside fullerene cages affords endohedral metallofullerenes (EMFs) classified as mono‐, di‐, tri‐, and cluster‐EMFs, respectively. Although the coexistence of various EMF species in soot is common for rare‐earth metals, we herein report that europium tends to prefer the formation of mono‐EMFs. Mass spectroscopy reveals that mono‐EMFs (Eu@C_2n) prevail in the Eu‐containing soot. Theoretical calculations demonstrate that the encapsulation energy of the endohedral metal accounts for the selective formation of mono‐EMFs and rationalize similar observations for EMFs containing other metals like Ca, Sr, Ba, or Yb. Consistently, all isolated Eu‐EMFs are mono‐EMFs, including Eu@D_3h(1)‐C₇₄, Eu@C_2v(19138)‐C₇₆, Eu@C_2v(3)‐C₇₈, Eu@C_2v(3)‐C₈₀, and Eu@D_3d(19)‐C₈₄, which are identified by crystallography. Remarkably, Eu@C_2v(19138)‐C₇₆ represents the first Eu‐containing EMF with a cage that violates the isolated‐pentagon‐rule, and Eu@C_2v(3)‐C₇₈ is the first C₇₈‐based EMF stabilized by merely one metal atom.     

Dawn of Calcium Batteries

Calcium batteries are a potentially sustainable, high‐energy‐density battery technology beyond Li ion batteries. Now the development of Ca batteries has become possible with a newly invented Ca electrolyte capable of reversible Ca deposition/stripping at room temperature.     

Energy‐dependent normal and unusually large inverse chlorine kinetic isotope effects of simple chlorohydrocarbons in collision‐induced dissociation by gas chromatography‐electron ionization‐tandem mass spectrometry

Kinetic isotope effects (KIEs) occurring in mass spectrometry (MS) can provide in‐depth insights into the fragmentation behaviors of compounds of interest in MS. Yet, the fundamentals of KIEs in collision‐induced dissociation (CID) in tandem mass spectrometry (MS/MS) are unclear, and information about chlorine KIEs (Cl‐KIEs) of organochlorines in MS is particularly scarce. This study investigated the Cl‐KIEs of dichloromethane, trichloroethylene, and tetrachloroethylene during CID using gas chromatography‐electron ionization triple‐quadrupole MS/MS. Cl‐KIEs were evaluated with MS signal intensities. All the organochlorines presented large inverse Cl‐KIEs (<1, the departures of Cl‐KIEs from 1 denote the magnitudes of Cl‐KIEs), showing the largest magnitudes of 0.797, 0.910, and 0.892 at the highest collision energy (60 eV) for dichloromethane, trichloroethylene, and tetrachloroethylene, respectively. For dichloromethane, both intra‐ion and inter‐ion Cl‐KIEs were studied, within the ranges of 0.820–1.020 and 0.797–1.016, respectively, showing both normal and inverse Cl‐KIEs depending on collision energies. The observed Cl‐KIEs generally declined from large normal to extremely large inverse values with increasing collision energies from 0 to 60 eV but were inferred to be independent of MS signal intensities. The Cl‐KIEs are dominated by critical energies at low internal energies of precursor ions, resulting in normal Cl‐KIEs; while at high internal energies, the Cl‐KIEs are controlled by rotational barriers (or looseness/tightness of transition states), which lead to isotope‐competitive reactions in dechlorination and thereby inverse Cl‐KIEs. It is concluded that the Cl‐KIEs may depend on critical energies, bond strengths, available internal energies, and transition state looseness/tightness. The findings of this study yield new insights into the fundamentals of Cl‐KIEs of organochlorines during CID and may be conducive to elucidating the underlying mechanisms of KIEs in collision‐induced and photo‐induced reactions in the actual world.     

Searching Hit Potential Antimicrobials in Natural Compounds Space against Biofilm Formation

Biofilms are communities of microorganisms that can colonize biotic and abiotic surfaces and thus play a significant role in the persistence of bacterial infection and resistance to antimicrobial. About 65% and 80% of microbial and chronic infections are associated with biofilm formation, respectively. The increase in infections by multi-resistant bacteria instigates the need for the discovery of novel natural-based drugs that act as inhibitory molecules. The inhibition of diguanylate cyclases (DGCs), the enzyme implicated in the synthesis of the second messenger, cyclic diguanylate (c-di-GMP), involved in the biofilm formation, represents a potential approach for preventing the biofilm development. It has been extensively studied using PleD protein as a model of DGC for in silico studies as virtual screening and as a model for in vitro studies in biofilms formation. This study aimed to search for natural products capable of inhibiting the Caulobacter crescentus enzyme PleD. For this purpose, 224,205 molecules from the natural products ZINC15 database, have been evaluated through molecular docking and molecular dynamic simulation. Our results suggest trans-Aconitic acid (TAA) as a possible starting point for hit-to-lead methodologies to obtain new inhibitors of the PleD protein and hence blocking the biofilm formation.     

Compromising Science by Ignorant Instrument Calibration—Need to Revisit Half a Century of Published XPS Data

X‐ray photoelectron spectroscopy (XPS) is an indispensable technique in modern materials science for the determination of chemical bonding as evidenced by more than 10 000 XPS papers published annually. A literature survey reveals that in the vast majority of cases an incorrect referencing of the binding energy scale is used, neglecting warnings that have been formulated from the early days of the technique. Consequences for the data reliability are disastrous and decades of XPS work require revisiting. The purpose of this Viewpoint is to highlight the existing problems, review the criticism and suggest ways forward.