Recent Submissions

  • Synthesis and characterization of second-generation phosphorus-nitrogen PN 3 P-rhodium (I) pincer complexes via ligand post-modification

    Zhou, Chunhui; Hu, Jinsong; Chakraborty, Priyanka; Huang, Kuo-Wei (Zeitschrift für anorganische und allgemeine Chemie, Wiley, 2021-05-07) [Article]
    A pseudo-dearomatized PN3P*Rh−CO complex reacts with various alkyl/benzyl halides to furnish a series of second-generation PN3P-pincer carbonyl complexes via the ligand post-modification strategy. These synthesized complexes were fully characterized by NMR, FTIR, HRMS, and single-crystal X-ray crystallography. A plausible mechanism for the formation of 2nd-generation PN3P complexes was proposed based on the isolation of the minor dialkylated products.
  • D936Y and Other Mutations in the Fusion Core of the SARS-CoV-2 Spike Protein Heptad Repeat 1: Frequency, Geographical Distribution, and Structural Effect.

    Oliva, Romina; Shaikh, Abdul Rajjak; Petta, Andrea; Vangone, Anna; Cavallo, Luigi (Molecules (Basel, Switzerland), MDPI AG, 2021-05-05) [Article]
    The crown of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is constituted by its spike (S) glycoprotein. S protein mediates the SARS-CoV-2 entry into the host cells. The "fusion core" of the heptad repeat 1 (HR1) on S plays a crucial role in the virus infectivity, as it is part of a key membrane fusion architecture. While SARS-CoV-2 was becoming a global threat, scientists have been accumulating data on the virus at an impressive pace, both in terms of genomic sequences and of three-dimensional structures. On 15 February 2021, from the SARS-CoV-2 genomic sequences in the GISAID resource, we collected 415,673 complete S protein sequences and identified all the mutations occurring in the HR1 fusion core. This is a 21-residue segment, which, in the post-fusion conformation of the protein, gives many strong interactions with the heptad repeat 2, bringing viral and cellular membranes in proximity for fusion. We investigated the frequency and structural effect of novel mutations accumulated over time in such a crucial region for the virus infectivity. Three mutations were quite frequent, occurring in over 0.1% of the total sequences. These were S929T, D936Y, and S949F, all in the N-terminal half of the HR1 fusion core segment and particularly spread in Europe and USA. The most frequent of them, D936Y, was present in 17% of sequences from Finland and 12% of sequences from Sweden. In the post-fusion conformation of the unmutated S protein, D936 is involved in an inter-monomer salt bridge with R1185. We investigated the effect of the D936Y mutation on the pre-fusion and post-fusion state of the protein by using molecular dynamics, showing how it especially affects the latter one.
  • Luminescent Copper(I) Halides for Optoelectronic Applications

    Yin, Jun; Lei, Qiong; Han, Yu; Bakr, Osman; Mohammed, Omar F. (Physica Status Solidi - Rapid Research Letters, Wiley, 2021-05-02) [Article]
    Lead-free copper(I) halides have been demonstrated to exhibit high photoluminescence quantum yields with high air and light stability, making them one of the most promising semiconductors for next-generation light-emitting diode devices. The low-dimensional structures and soft lattices of Cu(I) halides induce the formation of self-trapped excitons (STEs) to achieve broadband emissions with high quantum yields. Herein, the recent studies on the electronic and optical properties of Cu(I) halides (i.e., Cs3Cu2X5, CsCu2X3, and A2CuX3, where A = K+ or Rb+, X = Cl−, Br−, or I−) are reviewed and particular emphasis is placed on the role of the dimensionality and the halide in governing the electronic and optical properties (e.g., emission color and photoluminescence efficiency) via STEs. Several optoelectronic applications of Cu(I) halides are also discussed. In the last section, perspectives and challenges for the future development of Cu(I) halides in both optoelectronic and photocatalytic applications are outlined.
  • 18.4% Organic Solar Cells Using a High Ionization Energy Self-Assembled Monolayer as Hole Extraction Interlayer

    Lin, Yuanbao; Magomedov, Artiom; Firdaus, Yuliar; Kaltsas, Dimitris; El Labban, Abdulrahman; Faber, Hendrik; Naphade, Dipti R; Yengel, Emre; Zheng, Xiaopeng; Yarali, Emre; Chaturvedi, Neha; Loganathan, Kalaivanan; Gkeka, Despoina; Alshammari, Sanaa Hayel Nazil; Bakr, Osman; Laquai, Frédéric; Tsetseris, Leonidas; Getautis, Vytautas; Anthopoulos, Thomas D. (ChemSusChem, Wiley, 2021-04-29) [Article]
    Self-assembled monolayers (SAMs) based on Br-2PACz and MeO-2PACz molecules are investigated as hole-extracting interlayers in organic photovoltaics (OPVs). The highest occupied molecular orbital (HOMO) energies of these SAMs were measured at -6.01 and -5.30 eV for Br-2PACz and MeO-2PACz, respectively, and found to induce significant changes in the work function (WF) of indium-tin-oxide (ITO) electrodes upon chemical functionalization. OPV cells based on PM6:BTP-eC9:PC 71 BM using ITO/Br-2PACz anodes exhibit a maximum power conversion efficiency (PCE) of 18.4%, outperforming devices with ITO/MeO-2PACz (14.5%) and ITO/PEDOT:PSS (17.5%). The higher PCE is found to originate from the much higher WF of ITO/Br-2PACz (-5.81 eV) compared to ITO/MeO-2PACz (4.58 eV) and ITO/PEDOT:PSS (4.9 eV), resulting in lower interface resistance, improved hole transport/extraction, lower trap-assisted recombination, and longer carrier lifetimes. Importantly, the ITO/Br-2PACz electrode is chemically stable and after removal of the SAM it can be recycled and reused to construct fresh OPVs with equally impressive performance.
  • Chemically Induced Mismatch of Rings and Stations in [3]Rotaxanes

    Curcio, Massimiliano; Nicoli, Federico; Paltrinieri, Erica; Fois, Ettore; Tabacchi, Gloria; Cavallo, Luigi; Silvi, Serena; Baroncini, Massimo; Credi, Alberto (Journal of the American Chemical Society, American Chemical Society (ACS), 2021-04-29) [Article]
    The mechanical interlocking of molecular components can lead to the appearance of novel and unconventional properties and processes, with potential relevance for applications in nanoscience, sensing, catalysis, and materials science. We describe a [3]rotaxane in which the number of recognition sites available on the axle component can be changed by acid-base inputs, encompassing cases in which this number is larger, equal to, or smaller than the number of interlocked macrocycles. These species exhibit very different properties and give rise to a unique network of acid-base reactions that leads to a fine p<i>K</i><sub>a</sub> tuning of chemically equivalent acidic sites. The rotaxane where only one station is available for two rings exhibits a rich coconformational dynamics, unveiled by an integrated experimental and computational approach. In this compound, the two crown ethers compete for the sole recognition site, but can also come together to share it, driven by the need to minimize free energy without evident inter-ring interactions.
  • Low-Temperature Direct Electrochemical Methanol Reforming Enabled by CO-Immune Mo-based Hydrogen Evolution Catalysts

    Bau, Jeremy; Rueping, Magnus (Chemistry – A European Journal, Wiley, 2021-04-29) [Article]
    Hydrogen storage in the form of intermediate artificial fuels such as methanol is important for future chemical and energy applications, and the electrochemical regeneration of hydrogen from methanol is thermodynamically favorable compared to direct water splitting. However, CO produced from methanol oxidation can adsorb to H 2 evolution catalysts and drastically reduce catalyst activity. In this study, we report and explore the origins of CO immunity in Mo-containing H 2 evolution catalysts. Unlike conventional catalysts such as Pt or Ni, Mo-based catalysts display remarkable immunity to CO poisoning. The origin of this behavior in NiMo appears to arise from the apparent inability of CO to bind Mo in electrocatalytic conditions, with mechanistic consequences for the HER in these systems. This specific property of Mo-based HER catalysts makes them ideal in environments where poisons may be present.
  • Conversion of Pd(I) off-cycle species into highly efficient cross-coupling catalysts.

    Liu, Yaxu; Voloshkin, Vladislav A; Scattolin, Thomas; Cavallo, Luigi; Dereli, Busra; Cazin, Catherine S. J.; Nolan, Steven P. (Dalton transactions (Cambridge, England : 2003), Royal Society of Chemistry (RSC), 2021-04-28) [Article]
    We report on the facile conversion of [Pd2(μ-Cl)(μ-η3-R-allyl)(NHC)2] complexes, which are commonly considered undesirable off-cycle species in cross-coupling reactions, into active [PdCl(μ-Cl)(NHC)]2 pre-catalysts. All reactions proceed under mild conditions (40 °C, 1-2 hours in acetone) using inexpensive HCl as both an oxidant and chloride source. DFT calculations were performed to explore the possible mechanism of this transformation, which appears to involve a combination of two different pathways. Moreover this study provides insights into factors favoring and hindering Pd(i) dimer formation undesirable in catalysis.
  • Highly Active Heterogeneous Catalyst for Ethylene Dimerization Prepared by Selectively Doping Ni on the Surface of a Zeolitic Imidazolate Framework

    Chen, Cailing; Alalouni, Mohammed R.; Dong, Xinglong; Cao, Zhen; Cheng, Qingpeng; Zheng, Lirong; Meng, Lingkun; Guan, Chao; Liu, L. M.; Abou-Hamad, Edy; Wang, Jianjian; Shi, Zhan; Huang, Kuo-Wei; Cavallo, Luigi; Han, Yu (Journal of the American Chemical Society, American Chemical Society (ACS), 2021-04-28) [Article]
    The production of 1-butene by ethylene dimerization is an important chemical industrial process currently implemented using homogeneous catalysts. Here, we describe a highly active heterogeneous catalyst (Ni-ZIF-8) for ethylene dimerization, which consists of isolating Ni-active sites selectively located on the crystal surface of a zeolitic imidazolate framework. Ni-ZIF-8 can be easily prepared by a simple one-pot synthesis method in which site-specific anchoring of Ni is achieved spontaneously because of the incompatibility between the d<sup>8</sup> electronic configuration of Ni<sup>2+</sup> and the three-dimensional framework of ZIF-8. The full exposure and square-planar coordination of the Ni sites accounts for the high catalytic activity of Ni-ZIF-8. It exhibits an average ethylene turnover frequency greater than 1 000 000 h<sup>-1</sup> (1-butene selectivity >85%) at 35 °C and 50 bar, far exceeding the activities of previously reported heterogeneous catalysts and many homogeneous catalysts under similar conditions. Moreover, compared to molecular Ni complexes used as homogeneous catalysts for ethylene dimerization, Ni-ZIF-8 has significantly higher stability and shows constant activity during 4 h of continuous reaction. Isotopic labeling experiments indicate that ethylene dimerization over Ni-ZIF-8 follows the Cossee-Arlman mechanism, and detailed characterizations combined with density functional theory calculations rationalize this observed high activity.
  • Unlocking mixed oxides with unprecedented stoichiometries from heterometallic metal-organic frameworks for the catalytic hydrogenation of CO2

    Castells-Gil, Javier; Ould-Chikh, Samy; Ramírez, Adrian; Ahmad, Rafia; Prieto, Gonzalo; Gómez, Alberto Rodríguez; Garzon Tovar, Luis Carlos; Telalovic, Selvedin; Liu, Lingmei; Genovese, Alessandro; Padial, Natalia M.; Aguilar-Tapia, Antonio; Bordet, Pierre; Cavallo, Luigi; Martí-Gastaldo, Carlos; Gascon, Jorge (Chem Catalysis, Elsevier BV, 2021-04-26) [Article]
    Their complex surface chemistry and high oxygen lattice mobilities place mixed-metal oxides among the most important families of materials. Modulation of stoichiometry in mixed-metal oxides has been shown to be a very powerful tool for tuning optical and catalytic properties. However, accessing different stoichiometries is not always synthetically possible. Here, we show that the thermal decomposition of the recently reported metal-organic framework MUV-101(Fe, Ti) results in the formation of carbon-supported titanomaghemite nanoparticles with an unprecedented Fe/Ti ratio close to 2, not achievable by soft-chemistry routes. The resulting titanomaghemite phase displays outstanding catalytic activity for the production of CO from CO2 via the reverse water-gas shift (RWGS) reaction with CO selectivity values of ca. 100% and no signs of deactivation after several days on stream. Theoretical calculations suggest that the reaction proceeds through the formation of COOH* species, favoring in this way CO over other byproducts.
  • Enhancing power generation in microbial fuel cell using tungsten carbide on reduced graphene oxide as an efficient anode catalyst material

    Mohamed, Hend Omar; Talas, Sawsan Abo; Sayed, Enas T.; Park, Sung-Gwan; Eisa, Tasnim; Abdelkareem, Mohammad Ali; Fadali, Olfat A.; Chae, Kyu-Jung; Castaño, Pedro (Energy, Elsevier BV, 2021-04-26) [Article]
    Tungsten carbide (WC) and tungsten carbide on reduced graphene oxide (WC+rGO) nanolayers show outstanding performance as anode catalysts in microbial fuel cells for the simultaneous generation of power and treatment of wastewater. In this work, we synthesized these catalysts using simple and cost-effective urea glass route and reduction-carburization techniques. The pristine carbon felt (CF), WC/CF, and WC+rGO/CF anodes were characterized using several techniques and tested in a practical microbial fuel cell using industrial wastewater. We found that the unique features of WC/CF and WC+rGO/CF anodes, i.e., the surface area, biocompatibility, structure morphology, and catalytic activity, resulted in significant performance improvements. In particular, WC+rGO/CF exhibited a 4.4-, 7.6-, and 2.1-fold power density, current density, and coulombic efficiency, respectively, relative to the benchmark CF anode. This study confirms the potential use of WC+rGO/CF as a viable anode catalyst in microbial fuel cells on a larger scale.
  • Conducting Polyaniline for Antifouling Ultrafiltration Membranes: Solutions and Challenges.

    Lin, Cheng-Wei; Xue, Shuangmei; Ji, Chenhao; Huang, Shu-Chuan; Tung, Vincent; Kaner, Richard B (Nano letters, 2021-04-22) [Article]
    Conjugated polyaniline can impact the field of water filtration membranes due to its hydrophilic and antibacterial nature, facile and inexpensive synthesis procedure, heat and acid tolerance, and unique doping/dedoping chemistry. However, the gelation effect, its rigid backbone, and the limited hydrophilicity of polyaniline severely restrict the adaptability to membranes and their antifouling performance. This Mini Review summarizes important works of polyaniline-related ultrafiltration membranes, highlighting solutions to conquer engineering obstacles in processing and challenges in enhancing surface hydrophilicity with an emphasis on chemistry. As a pH-responsive polymer convertible to a conductive salt, this classic material should continue to bring unconventional advances into the realm of water filtration membranes.
  • A single-molecule van der Waals compass

    Shen, Boyuan; Chen, Xiao; Wang, Huiqiu; Xiong, Hao; Bosch, Eric G. T.; Lazić, Ivan; Cai, Dali; Qian, Weizhong; Jin, Shifeng; Liu, Xin; Han, Yu; Wei, Fei (Nature, Springer Science and Business Media LLC, 2021-04-21) [Article]
    Single-molecule imaging is challenging but highly beneficial for investigating intermolecular interactions at the molecular level<sup>1-6</sup>. Van der Waals interactions at the sub-nanometre scale strongly influence various molecular behaviours under confinement conditions<sup>7-11</sup>. Inspired by the traditional compass<sup>12</sup>, here we use a para-xylene molecule as a rotating pointer to detect the host-guest van der Waals interactions in the straight channel of the MFI-type zeolite framework. We use integrated differential phase contrast scanning transmission electron microscopy<sup>13-15</sup> to achieve real-space imaging of a single para-xylene molecule in each channel. A good correlation between the orientation of the single-molecule pointer and the atomic structure of the channel is established by combining the results of calculations and imaging studies. The orientations of para-xylene help us to identify changes in the van der Waals interactions, which are related to the channel geometry in both spatial and temporal dimensions. This work not only provides a visible and sensitive means to investigate host-guest van der Waals interactions in porous materials at the molecular level, but also encourages the further study of other single-molecule behaviours using electron microscopy techniques.
  • A multi-parametric catalyst screening for CO2 hydrogenation to ethanol

    Goryachev, Andrey; Pustovarenko, Alexey; Shterk, Genrikh; Alhajri, Nawal S.; Jamal, Aqil; Albuali, Mohammed; van Koppen, Luke; Khan, Il Son; Russkikh, Artem; Ramirez, Adrian; Shoinkhorova, Tuiana; Hensen, Emiel J. M.; Gascon, Jorge (ChemCatChem, Wiley, 2021-04-21) [Article]
    The direct hydrogenation of CO 2 to higher alcohols has the potential to turn the main contributor of global warming into a valuable feedstock. However, for this technology to become attractive, more efficient and, especially, selective catalysts are required. Here we present a high throughput study on the influence of different promoters on the CO 2 hydrogenation performance of Rh-SiO 2 catalysts. Fe and K promoters were found to improve ethanol selectivity at the expense of undesired CH 4 . The best-performing catalyst, with a composition 2 wt.% K, 20 wt.% Fe, and 5 wt.% Rh, displays an EtOH selectivity of 16% at CO 2 conversion level of 18.4% and CH 4 selectivity of 46%. The combination of different characterization techniques and catalyst screening allowed us to unravel the role of each catalyst component in this complex reaction mechanism.
  • Covalent Assembly of Two-Dimensional COF-on-MXene Heterostructures Enables Fast Charging Lithium Hosts

    Guo, Dong; Ming, Fangwang; Shinde, Digambar; Cao, Li; Huang, Gang; Li, Chunyang; Li, Zhen; Yuan, Youyou; Hedhili, Mohamed N.; Alshareef, Husam N.; Lai, Zhiping (Advanced Functional Materials, Wiley, 2021-04-16) [Article]
    2D heterostructured materials combining ultrathin nanosheet morphology, defined pore configuration, and stable hybrid compositions, have attracted increasing attention for fast mass transport and charge transfer, which are highly desirable features for efficient energy storage. Here, the chemical space of 2D–2D heterostructures is extended by covalently assembling covalent organic frameworks (COFs) on MXene nanosheets. Unlike most COFs, which are generally produced as solid powders, ultrathin 2D COF-LZU1 grows in situ on aminated Ti3C2Tx nanosheets with covalent bonding, producing a robust MXene@COF heterostructure with high crystallinity, hierarchical porosity, and conductive frameworks. When used as lithium hosts in Li metal batteries, lithium storage and charge transport are significantly improved. Both spectroelectrochemical and theoretical analyses demonstrate that lithiated COF channels are important as fast Li+ transport layers, by which Li ions can be precisely nucleated. This affords dendrite-free and fast-charging anodes, which would be difficult to achieve using individual components.
  • Need for Rationally Designed SnWO4 Photo(electro)catalysts to Overcome the Performance Limitations for O2 and H2 Evolution Reactions

    Azofra Mesa, Luis; Cavallo, Luigi; Basset, Jean-Marie; Harb, Moussab (The Journal of Physical Chemistry C, American Chemical Society (ACS), 2021-04-16) [Article]
    Although the α-SnWO4 material has recently been considered as a new good candidate for visible-light-driven photo(electro)chemical water splitting, the performance is still low and requires further improvement. Here, we present a deep fundamental work on the influence of the various possible facets exposed on this material for oxygen and hydrogen evolution reactions using hybrid density functional theory. The energetic, electronic, water redox, and charge carrier transport features of the four possible (100), (010), (001), and (110) facets (low-Miller index surfaces) are investigated, and significant anisotropic nature is revealed. The relevant properties of each facet to the water oxidation/reduction reactions are correlated with the surface W coordination number. Taking into account the stability and combining optoelectronic and water redox features together of each surface, our work demonstrates that the (110) facet is photocatalytically the best candidate for the OER, while the (100) facet is the best candidate for the HER. Their transport characteristics are found to be much better than those obtained for the three major (121), (210), and (111) facets of synthesized α-SnWO4 samples. Substitutional Ge at the Sn site and Mo at the W site on the two (110) and (100) facets are expected to increase the rates of the water oxidation/reduction reactions. An analysis of the reaction mechanism for the OER in (110)-oriented α-SnWO4 reveals a promising performance of this facet for electrocatalytic water oxidation. These outcomes will greatly motivate experimentalists for carefully designing (110)- and (100)-oriented α-SnWO4 samples to enhance the photo(electro)catalytic OER and photocatalytic HER performances.
  • Intriguing Ultrafast Charge Carrier Dynamics in Two-Dimensional Ruddlesden–Popper Hybrid Perovskites

    Yin, Jun; Bakr, Osman; Mohammed, Omar F. (The Journal of Physical Chemistry C, American Chemical Society (ACS), 2021-04-16) [Article]
    Two-dimensional (2D) Ruddlesden–Popper (RP) hybrid perovskites are among the most promising semiconductor candidates for next-generation highly efficient optoelectronic devices due to their impressive optical and transport properties. More importantly, 2D hybrid perovskites exhibit much higher structural and chemical stability against moisture and light radiation levels than their 3D counterparts, indicating a wide range of potential applications and commercialization. The highly ordered multiple-quantum-well structures of 2D RP perovskites give rise to several optoelectronic properties that can be effectively tuned by compositional engineering of organic spacers and inorganic layer thicknesses. In this Perspective, we review recent studies of charge carrier dynamics in 2D RP perovskites. More specifically, we focus on understanding how organic cations and the number of inorganic layers govern the ultrafast charge carrier dynamics in 2D RP perovskites. We also highlight our recent work on hot-carrier cooling dynamics, Rashba band splitting, and narrowband and broadband emissions in various 2D RP hybrid perovskites. We also provide a perspective on the future studies of 2D RP perovskites, including structure–property relationships, and remaining questions on the charge carrier dynamics, including hot-carrier extractions.
  • Outstanding performance of direct urea/hydrogen peroxide fuel cell based on precious metal-free catalyst electrodes

    Eisa, Tasnim; Park, Sung Gwan; Mohamed, Hend Omar; Abdelkareem, Mohammad Ali; Lee, Jieun; Yang, Euntae; Castaño, Pedro; Chae, Kyu Jung (Energy, Elsevier BV, 2021-04-08) [Article]
    Direct urea/hydrogen peroxide fuel cells (DUHP-FCs) can produce electrical energy by recycling urea-rich wastewater. This study expands the commerciality of DUHP-FC by removing precious metals from their design. Nickel nanorod/nickel foam (NNR/NF) was fabricated using hydrothermal treatment to be used as the anode, and Prussian blue coating was deposited by potentiostatic electrodeposition onto hydrophilic carbon felt at the cathode (PB/CF). The anode exhibited a 7-folds higher current density than bare NF at 0–2 M urea, and lower charge transfer resistance. The cathode reported a high H2O2 reduction current. In addition, fuel cell tests indicated current density dependency on H2O2 concentration and cell voltage dependency on KCl concentration. A competitive maximum power density of 10.6 mW cm−2 was achieved at 0.98 open circuit voltage and 45 mA cm−2 maximum current density, in 0.33 M urea vs 2 M KCl and 2 M H2O2, exclusively via diffusive mass transfer. These findings indicate the practical application of DUHP-FC on a large scale.
  • Synthesis of gold(I)-trifluoromethyl complexes and their role in generating spectroscopic evidence for a gold(I)-difluorocarbene species.

    Nolan, Steven Patrick; Vanden Broeck, Sofie M P; Nelson, David J; Collado, Alba; Falivene, Laura; Cavallo, Luigi; Cordes, David B; Slawin, Alexandra M Z; Van Hecke, Kristof; Nahra, Fady; Cazin, Catherine S J (Chemistry (Weinheim an der Bergstrasse, Germany), Wiley, 2021-04-06) [Article]
    Readily-prepared and bench-stable [Au(CF 3 )(NHC)] compounds were synthesized using new methodologies, starting from [Au(OH)(NHC)], [Au(Cl)(NHC)] or [Au(L)(NHC)]HF 2 precursors (NHC = N-heterocyclic carbene). The mechanism of formation of these species was investigated. Consequently, a new and straightforward strategy for the mild and selective cleavage of a single carbon-fluorine bond from [Au(CF 3 )(NHC)] complexes was attempted and found to be reversible in the presence of an additional nucleophilic fluoride source. This straightforward technique has led to the unprecedented spectroscopic observation of a gold(I)-NHC difluorocarbene species.
  • Lithium-Ion Desolvation Induced by Nitrate Additives Reveals New Insights into High Performance Lithium Batteries

    Wahyudi, Wandi; Ladelta, Viko; Tsetseris, Leonidas; Alsabban, Merfat; Guo, Xianrong; Yengel, Emre; Faber, Hendrik; Adilbekova, Begimai; Seitkhan, Akmaral; Emwas, Abdul-Hamid M.; Hedhili, Mohamed N.; Li, Lain-Jong; Tung, Vincent; Hadjichristidis, Nikos; Anthopoulos, Thomas D.; Ming, Jun (Advanced Functional Materials, Wiley, 2021-04-02) [Article]
    Electrolyte additives have been widely used to address critical issues in current metal (ion) battery technologies. While their functions as solid electrolyte interface forming agents are reasonably well-understood, their interactions in the liquid electrolyte environment remain rather elusive. This lack of knowledge represents a significant bottleneck that hinders the development of improved electrolyte systems. Here, the key role of additives in promoting cation (e.g., Li+) desolvation is unraveled. In particular, nitrate anions (NO3−) are found to incorporate into the solvation shells, change the local environment of cations (e.g., Li+) as well as their coordination in the electrolytes. The combination of these effects leads to effective Li+ desolvation and enhanced battery performance. Remarkably, the inexpensive NaNO3 can successfully substitute the widely used LiNO3 offering superior long-term stability of Li+ (de-)intercalation at the graphite anode and suppressed polysulfide shuttle effect at the sulfur cathode, while enhancing the performance of lithium–sulfur full batteries (initial capacity of 1153 mAh g−1 at 0.25C) with Coulombic efficiency of ≈100% over 300 cycles. This work provides important new insights into the unexplored effects of additives and paves the way to developing improved electrolytes for electrochemical energy storage applications.
  • Theory-Guided Synthesis of Highly Luminescent Colloidal Cesium Tin Halide Perovskite Nanocrystals

    Liu, Qi; Yin, Jun; Zhang, Bin-Bin; Chen, Jia-Kai; Zhou, Yang; Zhang, Lu-Min; Wang, Lu-Ming; Zhao, Qing; Hou, Jingshan; Shu, Jie; Song, Bo; Shirahata, Naoto; Bakr, Osman; Mohammed, Omar F.; Sun, Hong-Tao (Journal of the American Chemical Society, American Chemical Society (ACS), 2021-04-01) [Article]
    The synthesis of highly luminescent colloidal CsSnX<sub>3</sub> (X = halogen) perovskite nanocrystals (NCs) remains a long-standing challenge due to the lack of a fundamental understanding of how to rationally suppress the formation of structural defects that significantly influence the radiative carrier recombination processes. Here, we develop a theory-guided, general synthetic concept for highly luminescent CsSnX<sub>3</sub> NCs. Guided by density functional theory calculations and molecular dynamics simulations, we predict that, although there is an opposing trend in the chemical potential-dependent formation energies of various defects, highly luminescent CsSnI<sub>3</sub> NCs with narrow emission could be obtained through decreasing the density of tin vacancies. We then develop a colloidal synthesis strategy that allows for rational fine-tuning of the reactant ratio in a wide range but still leads to the formation of CsSnI<sub>3</sub> NCs. By judiciously adopting a tin-rich reaction condition, we obtain narrow-band-emissive CsSnI<sub>3</sub> NCs with a record emission quantum yield of 18.4%, which is over 50 times larger than those previously reported. Systematic surface-state characterizations reveal that these NCs possess a Cs/I-lean surface and are capped with a low density of organic ligands, making them an excellent candidate for optoelectronic devices without any postsynthesis ligand management. We showcase the generalizability of our concept by further demonstrating the synthesis of highly luminescent CsSnI<sub>2.5</sub>Br<sub>0.5</sub> and CsSnI<sub>2.25</sub>Br<sub>0.75</sub> NCs. Our findings not only highlight the value of computation in guiding the synthesis of high-quality colloidal perovskite NCs but also could stimulate intense efforts on tin-based perovskite NCs and accelerate their potential applications in a range of high-performance optoelectronic devices.

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