Electrolyte Regulation of Bio-Inspired Zincophilic Additive toward High-Performance Dendrite-Free Aqueous Zinc-Ion Batteries.

Aqueous zinc-ion batteries hold attractive potential for large-scale energy storage devices owing to their prominent electrochemical performance and high security. Nevertheless, the applications of aqueous electrolytes have generated various challenges, including uncontrolled dendrite growth and parasitic reactions, thereby deteriorating the Zn anode's stability. Herein, inspired by the superior affinity between Zn2+ and amino acid chains in the zinc finger protein, a cost-effective and green glycine additive is incorporated into aqueous electrolytes to stabilize the Zn anode. As confirmed by experimental characterizations and theoretical calculations, the glycine additives can not only reorganize the solvation sheaths of hydrated Zn2+ via partial substitution of coordinated H2 O but also preferentially adsorb onto the Zn anode, thereby significantly restraining dendrite growth and interfacial side reactions. Accordingly, the Zn anode could realize a long lifespan of over 2000 h and enhanced reversibility (98.8%) in the glycine-containing electrolyte. Furthermore, the assembled Zn||α-MnO2 full cells with glycine-modified electrolyte also delivers substantial capacity retention (82.3% after 1000 cycles at 2 A g-1 ), showing promising application prospects. This innovative bio-inspired design concept would inject new vitality into the development of aqueous electrolytes.

Construction of Bio-inspired Film with Engineered Hydrophobicity to Boost Interfacial Reaction Kinetics of Aqueous Zinc-Ion Batteries.

Aqueous zinc-ion batteries typically suffer from sluggish interfacial reaction kinetics and drastic cathode dissolution owing to the desolvation process of hydrated Zn2+ and continual adsorption/desorption behavior of water molecules, respectively. To address these obstacles, a bio-inspired approach, which exploits the moderate metabolic energy of cell systems and the amphiphilic nature of plasma membranes, is employed to construct a bio-inspired hydrophobic conductive poly(3,4-ethylenedioxythiophene) film decorating α-MnO2 cathode. Like plasma membranes, the bio-inspired film can "selectively" boost Zn2+ migration with a lower energy barrier and maintain the integrity of the entire cathode. Electrochemical reaction kinetics analysis and theoretical calculations reveal that the bio-inspired film can significantly improve the electrical conductivity of the electrode, endow the cathode-electrolyte interface with engineered hydrophobicity, and enhance the desolvation behavior of hydrated Zn2+ . This results in an enhanced ion diffusion rate and minimized cathode dissolution, thereby boosting the overall interfacial reaction kinetics and cathode stability. Owing to these intriguing merits, the composite cathode can demonstrate remarkable cycling stability and rate performance in comparison with the pristine MnO2 cathode. Based on the bio-inspired design philosophy, this work can provide a novel insight for future research on promoting the interfacial reaction kinetics and electrode stability for various battery systems.

High-Efficiency Non-Fullerene Acceptors Developed by Machine Learning and Quantum Chemistry.

Y6 and its derivatives have greatly improved the power conversion efficiency (PCE) of organic photovoltaics (OPVs). Further developing high-performance Y6 derivative acceptor materials through the relationship between the chemical structures and properties of these materials will help accelerate the development of OPV. Here, machine learning and quantum chemistry are used to understand the structure-property relationships and develop new OPV acceptor materials. By encoding the molecules with an improved one-hot code, the trained machine learning model shows good predictive performance, and 22 new acceptors with predicted PCE values greater than 17% within the virtual chemical space are screened out. Trends associated with the discovered high-performing molecules suggest that Y6 derivatives with medium-length side chains have higher performance. Further quantum chemistry calculations reveal that the end acceptor units mainly affect the frontier molecular orbital energy levels and the electrostatic potential on molecular surface, which in turn influence the performance of OPV devices. A series of promising Y6 derivative candidates is screened out and a rational design guide for developing high-performance OPV acceptors is provided. The approach in this work can be extended to other material systems for rapid materials discovery and can provide a framework for designing novel and promising OPV materials.

Controlling the quantity of γ-Fe inside multiwall carbon nano-onions: the key role of sulfur.

One of the most interesting structural features of multiwall carbon onions (MWCNOs) and nanotubes (MWCNTs) is the excellent chemical stability, which allows in situ encapsulation of chosen magnetic materials of interest and multifunctional applications. In this letter, we present an innovative chemical vapour synthesis (CVS) approach, in which the inclusion of small quantities of sulfur during the pyrolysis of ferrocene/dichlorobenzene mixtures allows for an important control in the relative abundance of FCC γ-Fe, up to a maximum value of ∼86.5% (structural- and phase-control). The variation in the relative percentage of the encapsulated Fe-based phases was estimated by employing X-ray diffraction (XRD) and Rietveld refinement analyses. The magnetic characterization was achieved by employing superconducting quantum interference device (SQUID) magnetometry, with zero field cooled (ZFC) and field cooled (FC) curves acquired at applied fields of 300 Oe and ∼50 000 Oe.

Tuning the carrier type and density of monolayer tin selenide via organic molecular doping.

Utilizing first-principles calculations, charge transfer doping process of single layer tin selenide (SL-SnSe) via the surface adsorption of various organic molecules was investigated. Effective p-type SnSe, with carrier concentration exceeding 3.59 × 1013 cm-2, was obtained upon adsorption of tetracyanoquinodimethane or 2,3,5,6-tetrafluoro-7,7,8,8-tetracyano-quinodimethane on SL-SnSe due to their lowest unoccupied molecular orbitals acting as shallow acceptor states. While we could not obtain effective n-type SnSe through adsorption of tetrathiafulvalene (TTF) or 1,4,5,8-tetrathianaphthalene on pristine SnSe due to their highest occupied molecular orbitals (HOMO) being far from the conduction band edge of SnSe, this disadvantageous situation can be amended by the introduction of an external electric field perpendicular to the monolayer surface. It is found that Snvacwill facilitate charge transfer from TTF to SnSe through introducing an unoccupied gap state just above the HOMO of TTF, thereby partially compensating for the p-type doping effect of Snvac. Our results show that both effective p-type and n-type SnSe can be obtained and tuned by charge transfer doping, which is necessary to promote its applications in nanoelectronics, thermoelectrics and optoelectronics.

Artificial Intelligence Designer for Highly-Efficient Organic Photovoltaic Materials.

Designing efficient organic photovoltaic (OPV) materials purposefully is still challenging and time-consuming. It is of paramount importance in material development to identify basic functional units that play the key roles in material performance and subsequently establish the substructure-property relationship. Herein, we describe an automatic design framework based on an in-house designed La FREMD Fingerprint and machine learning (ML) algorithms for highly efficient OPV donor molecules. The key building blocks are identified, and a library consisting of 18 960 new molecules is generated within this framework. Through investigating the chemical structures of materials with different performance, a guidance on designing efficient OPV materials is proposed. Furthermore, the most promising candidates exhibit a predicted power conversion efficiency (PCE) value of over 15% when combined with acceptor Y6. Density functional theory (DFT) studies show these candidate materials possess exceptional potential for efficient charge carrier transport. The proposed framework demonstrates the ability to design new materials based on the substructure-property relationship built by ML, which provides an alternative methodology for applying ML in new material discovery.

Vacancy-induced interfacial ferromagnetic features in SmFeO3-filled graphitic carbon foam.

We report a novel structural and magnetic investigation of carbon foam (CFM) materials filled with SmFeO3 crystals produced by (1) high temperature fusion between Sm2O3- and Fe3C-filled carbon onions and (2) annealing of iron filled CFM with nanosized Sm2O3. Presence of a defect-rich monolayer-like CFM arrangement characterized by sharp interfaces with a SmFeO3 single-crystal phase is demonstrated through TEM and HRTEM. Further, the presence of intense sp3-rich features with variable carbonate content is evidenced by XPS and Raman spectroscopy. Complementary VSM, SQUID and ESR show also presence of intrinsic magnetization features which appeared to be attributable to the interfacial vacancy-rich regions of the graphitic CFM layers, as confirmed by Raman spectroscopy. Together with these signals, possible ferromagnetic contributions from the SmFeO3 phase and α-Fe impurities are reported. These observations highlight therefore the presence of switchable interfacial magnetization features at the carbon/SmFeO3 interface due to the variable concentrations of vacancies at the CFM interface, opening new directions towards applications in magnetic and interfacial-driven ferroelectric devices.