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Since the 1960s, poly(benzobisimidazobenzophenathrolinedione) (BBL) has been the only n-type ladder-type conjugated polymer (LCP) that is utilized in thin film electronic devices. Its high electrochemical and thermal stabilities make it a promising candidate for organic electrochemical transistors (OECTs) and thermoelectrics (OTEs) applications. Here we report the synthesis and characterization of a new π-extended poly(benzimidazoanthradiisoquinolinedione) (BAL). The tetrachlorinated BAL (Cl4-BAL) is fully soluble in methanesulfonic acid (MSA) and can be spin-coated into good quality thin films, enabling the fabrication and characterization of OTEs. Doping of Cl4-BAL films using our in-house benzyl viologen radical cation (BV

Conjugated polymers are promising materials for thermoelectrics as they offer good performances at near ambient temperatures. The current focus on polymer thermoelectric research mainly targets a higher power factor (PF; a product of the conductivity and square of the Seebeck coefficient) through improving the charge mobility. This is usually accomplished

The first working lithium-ion battery containing polymer electrolytes derived from waste poly(ethylene terephthalate) beverage bottles is demonstrated.

Doping high electrical conductivity Nb5Ge3 precipitates into GeTe results in nanoprecipitates phonon scattering, while retaining electrical mobility. As a result, thermoelectric zT of GeTe is drastically enhanced to 2.0 at 723 K.

Here we report the synthesis of a new solubilizing group-free, solution-processable

GeTe is among the best medium-temperature thermoelectrics. Its high performance originates from band convergence at the phase transition and low lattice thermal conductivity due to Peierls distortion. In most studies, the peak performance (zT) in GeTe is achieved by designing and optimizing its electronic and thermal transport properties near its phase transition temperature (700 K). However, for efficient power harvesting, a high average zT (zT(ave)) across a wide temperature range is desirable. This calls for a holistic performance evaluation and enhancement not only near 700 K, but also at room temperature. In this work, we leveraged on the confluence of performance enhancement strategies via Cu2Te alloying and In resonant doping to achieve a record-high room temperature power factor of 2800 mu W mK-2, and an average power factor of 3700 mu W mK-2 between 323 and 773 K. The magnitude of the room temperature power factor is comparable to that of the state-of-the-art Bi2Te3 based compounds. In the optimized sample with Bi doping, a room temperature zT of 0.5 is achieved, highest for lead-free GeTe. Ultimately, a high peak zT of 2.1 at 723 K and single leg power conversion efficiency of 11.8% were achieved between 323 and 745 K, which are among the highest reported for lead-free GeTe. Agency for Science, Technology and Research (A*STAR) Ministry of Education (MOE) The authors acknowledge support from the A*STAR's Science and Engineering Research Council Sustainable Hybrid Lighting System for Controlled Environment Agriculture programme: A19D9a0096. Q. Yan acknowledges Singapore MOE AcRF Tier 2 under Grant No. 2018-T2-1-010, Singapore A*STAR project A19D9a0096. A. S. acknowledges funding from the A*STAR's Career Development Award number C210112022.

Nanostructuring is an effective way to concurrently improve thermal and electrical parameters in some thermoelectric material systems. Herein, we have established that thermoelectric properties of ...

Two decades after the rapid expansion of photovoltaics, the number of solar panels reaching end-of-life is increasing. While precious metals such as silver and copper are usually recycled, silicon, which makes up the bulk of a solar cells, goes to landfills. This is due to the defect- and impurity-sensitive nature in most silicon-based technologies, rendering it uneconomical to purify waste silicon. Thermoelectrics represents a rare class of material in which defects and impurities can be engineered to enhance the performance. This is because of the majority-carrier nature, making it defect- and impurity-tolerant. Here, the upcycling of silicon from photovoltaic (PV) waste into thermoelectrics is enabled. This is done by doping 1% Ge and 4% P, which results in a figure of merit (zT) of 0.45 at 873 K, the highest among silicon-based thermoelectrics. The work represents an important piece of the puzzle in realizing a circular economy for photovoltaics and electronic waste. Agency for Science, Technology and Research (A*STAR) Ministry of National Development (MND) National Environmental Agency (NEA) A.S. acknowledges funding from A*STAR (Agency of Science, Technology and Research) Career Development Fund (CDF) no. C210112022. J.X acknowledges A*STAR “Sustainable Hybrid Lighting System for Controlled Environment Agriculture programme”: A19D9a0096. Z.L. would also like to express gratitude to the financial support from the A∗STAR’s Science and Engineering Research Council (SERC) Central Research Fund (Use-inspired Basic Research) for this work. N.M. and Q.Y. acknowledge grant award from NEA (National Environmental Agency, Singapore) and Ministry of National Development (MND, Singapore) titled “Singapore–CEA Alliance for Research in Circular Economy (SCARCE, award number USS-IF-2018-4),” which is a joint lab set up between Nanyang Technological University (NTU, Singapore) and the French Alternative Energies and Atomic Energy Commission (CEA, France).

Robust electronic transport properties is a crucial in designing high performance thermoelectrics. A key similarity between superconductor and thermoelectric lies in their generally high electrical conductivity, even at above its superconducting temperature. In this work, we design a nanocomposite between Nb

Here, we report the use of two high-spin pro-quinoid benzo[1,2-c;4,5-c′]bisthiadiazole (BBT) polymers for high-performance solution-processable polymer thermoelectrics. Sequential solution-phase do...

GeTe as one of the most promising medium temperature thermoelectrics has progressed leaps and bounds in recent years, largely thanks to a combination of its unique electronic, thermal and structural properties. Despite its various advantages, a major factor standing in the way of wide commercial adoptions lies in its unreliable mechanical properties. This work reports Re doping as a strategy to drastically enhance the mechanical properties of GeTe, resulting in Vickers microhardness as high as 342.6 Hv in Ge0.88Sb0.10Re0.02Te, which is more than double that of pristine GeTe (145 Hv). Ge0.88Sb0.10Re0.02Te also exhibited a Young's modulus of 64.1 GPa, substantially higher than many other binary chalcogenide thermoelectrics. The significant enhancement of GeTe in mechanical properties is mainly related to the mechanism of precipitation hardening. In addition, we found that while the electronic properties were slightly compromised with Re doping, the lattice thermal conductivity was reduced due to point defects scattering brought about by Re atoms. Therefore, a high zT value (>1.6) at 600–800 K is achieved in Ge0.88Sb0.10Re0.02Te. Furthermore, above 10% device efficiency can be expected for the operating temperature between 300–800 K. Such a solution to strengthen the mechanical properties of GeTe using Re doping is expected to play a major part in the push for full-scale GeTe-based thermoelectric devices.

Gel polymer electrolytes are an important advancement in energy storage technology due to their enhanced safety and practical ionic conductivities at ambient temperatures. Herein, a simple one-step facile synthesis of chemically crosslinked polyurethanes containing polyethylene oxide (PEO) and polypropylene oxide (PPO) macromolecular segments was developed, using ubiquitous non-toxic tetrabutylammonium or potassium chloride and bromide salts as catalysts. These salts were shown to catalyze the gelation of diol-diisocyanate polyaddition reactions within minutes. When impregnated with a liquid electrolyte, the resulting gel electrolyte exhibited a practical ionic conductivity of 1.1×10-4 S cm-1 at 40 °C and low segmental chain motion activation energy (11 kJ mol-1 ). These findings further promote PEO-PPO polyurethanes as a biocompatible class of materials suitable for further exploration as gel polymer electrolytes for supercapacitors.

GeTe is highly sought-after due to its versatility as high-performance thermoelectrics, phase change materials, as well as ferroelectric Rashba semiconductor. Compared to most thermoelectric materials, it has an additional degree of freedom of rhombohedral-cubic phase transition at 673 K. At this temperature, the lattice thermal conductivity approaches theoretical minimum due to ferroelectric instability while the high-energy Σ and low-energy L bands converge to give outstanding electronic properties. Therefore, modulation of the phase transition temperature allows simultaneous and synergistic tuning of electronic and thermal transport properties to achieve high zT. In this work, Sn alloying together with Bi, Sb doping is used to suppress the phase transition to achieve a pure cubic structure with lattice thermal conductivity of around 0.4 W/mK and peak zT of 1.7 at 723 K with average zT of 1.23 between 400 and 800 K. Furthermore, Vickers hardness of 270, and Young’s modulus of 63.5 GPa in Ge0.4Sn0.4Bi0.02Sb0.12Te is by far the highest amongst binary chalcogenides. More importantly, the high quality factor achieved in this work enables ample room for further zT improvements. The fundamental insights drawn from this work provide a pathway towards engineering GeTe-based alloys to achieve high zT at any temperature of interest. Agency for Science, Technology and Research (A*STAR) Ministry of Education (MOE) Accepted version

We clarify the reactions in a lithium–sulfur cell by in situ monitoring the change in viscosity of its electrolyte. The results have revealed that Li2S2 is a soluble substance in the electrolyte. This contradicts what was suggested in the literature that it is a solid precipitate on the electrode.

We report Ni/NiOx nanoparticle-decorated carbon nanofibers, produced via electrospinning with subsequent heat treatments, as efficient oxygen evolution reaction catalysts for rechargeable Zn–air batteries with superior performances.

With new chemistry and advantageous configuration, the lithium-oxygen (Li-O2) battery promises a much higher specific energy than traditional lithium-ion batteries. The limited understanding on the complicated battery reactions therein, however, has become a major bottleneck of its development for applications requiring a high energy efficiency and long cycle-life. Herein, in a confined potential window with negligible electrolyte degradation, we studied the rechargeability of Li-O2 cathodes with pre-filled well-defined discharge products of Li2O2, Li2CO3, LiOH, or their combinations. Our results suggest Li2CO3 as the most difficult species to be electrochemically decomposed among the three lithium compounds, whereas the presence of LiOH notably increases the initial charge potential. The clearly visible difference in the charge behavior and cycling stability of these artificially "discharged" electrodes provides a guideline for the development of future high-performance Li-O2 batteries.

We report for the first time a novel method to synthesize sulfur–carbon yolk–shell particles with sulfur fully confined inside the conductive carbon shells, and the filling content of sulfur can be well-controlled and fine-tuned. In the yolk–shell structure the sulfur spheres partially occupy the internal void space of highly conductive carbon, allowing for comfortable accommodation of the volume expansion of sulfur upon lithiation during the battery discharge process. 3D interconnected nanostructures based on such sulfur–carbon yolk–shell particles exhibit a high initial capacity of 560 mA h g−1 (per gram electrode) with good cycling performance, promising high potential in rechargeable lithium–sulfur batteries for a wide range of applications.

We report cobalt sulfide nanoparticles decorated nitrogen and sulfur co-doped graphene nanosheets as an effective bifunctional oxygen catalyst. Its oxygen evolution reaction (OER) catalytic activity outperforms Pt/C, giving a current density of 38.19 mA cm−2 at 1.0 V. Zn–air batteries using this material on air-cathode show high stability and good rechargeability.

In this paper, we discuss some key parameters in design of lithium sulfur batteries with high energy density, in particular carbon/sulfur ratio, sulfur loading density, electrolyte volume and electrode deformability, which directly impact the battery performance in terms of capacity, cycleability, and processibilities, etc. We find that a carbon to sulfur ratio of 1:2 (w/w) in the electrode is good for high specific capacity, giving a capacity of 538 mA h g −1 which is 3 times as high as that of LiCoO 2 cathode. The issue of fragileness for electrode at high sulfur loading density is mitigated by replacing carbon black with fine graphite powders. With these optimizations the carbon–sulfur electrode gives an energy density of 5.88 mW h cm −2 which corresponds to 60% of that of the commercial LiCoO 2 electrode.

Porous carbon materials play key roles in rechargeable Li–O2 batteries as oxygen diffusion media and sites for reversible electrode reactions. Despite tremendous efforts in the synthesis of various porous carbon materials, the influence of carbon materials on cell capacity remains unclear. Based on our study of eight different carbon electrode materials with various pore sizes and pore volumes in Li–O2 batteries, we found that the initial discharge capacity was hardly affected by the surface area or pore volume. Instead, it was directly correlated with the pore sizes. To further verify this finding, meso- and macro-porous carbon materials with pore sizes in the range of 20 to 100 nm were prepared using spherical silica as a template. The results clearly showed that the cell capacity increases with the increase of pore size and eventually reached its maximum at 7169 mA h g−1 at a pore size of 80 nm. A physical model proposed to illustrate the influence of carbon pore size on cell capacity is the formation of a monolayer of Li2O2 with a thickness of 7.8 nm inside the carbon pores during the discharge process which limits the diffusion of incoming oxygen at smaller pore size (

Lithium nitrate (LiNO3) is known as an important electrolyte additive in lithium-sulfur (Li-S) batteries. The prevailing understanding is that LiNO3 reacts with metallic lithium anode to form a passivation layer which suppresses redox shuttles of lithium polysulfides, enabling good rechargeability of Li-S batteries. However, this view is seeing more challenges in the recent studies, and above all, the inability of inhibiting polysulfide reduction on Li anode. A closely related issue is the progressive reduction of LiNO3 on Li anode which elevates internal resistance of the cell and compromises its cycling stability. Herein, we systematically investigated the function of LiNO3 in redox-shuttle suppression, and propose the suppression as a result of catalyzed oxidation of polysulfides to sulfur by nitrate anions on or in the proximity of the electrode surface upon cell charging. This hypothesis is supported by both density functional theory calculations and the nitrate anions-suppressed self-discharge rate in Li-S cells. The catalytic mechanism is further validated by the use of ruthenium oxide (RuO2, a good oxygen evolution catalyst) on cathode, which equips the LiNO3-free cell with higher capacity and improved capacity retention over 400 cycles.

This review summarises some recent developments of the metal complexes of hetero-functional hybrid ligands of C-, N-, O-, P- and S-donors. It highlights the ligand designs, synthetic pathways, structural motifs and catalytic prowess of these complexes.

Lewis acid/base addition between Pd2(dppf)2(μ-S)2 and MXn [M = In(III), Ga(III), Tl(I), Pb(II), Sn(IV), Bi(III), Ag(I) and Au(I); X = halide or pseudohalide; dppf = 1,1′-bis(diphenylphosphino)ferrocene] gives rise to a range of neutral or cationic intermetallics aggregates with the {Pd2MS2} or {Pd2M2S2} core. Effectively Pd2(dppf)2(μ-S)2 functions as a chelating or bridging dithio metalloligand. Two representative crystal structures, viz. [InPd2Cl3(dppf)2(μ3-S)2] · 3CH2Cl2 and [Ag2Pd2(NO3)2(dppf)2(μ3-S)2] · 2CH2Cl2 are described and discussed. The former features an intermetallic {InPd2} triangle whereas the latter displays a heterometallic {Ag2Pd2} metal plane. Both of them are sustained and supported by capping sulfides without significant or direct metal–metal bonds.

The cyclometallated Pd compound PdCl[PPh2CH2CH2CHCH2CH2PPh2] 1, obtained from PdCl2(Ph2P(CH2)5PPh2) in refluxing DMF (N,N-dimethylformamide), was characterized by NMR and X-ray single-crystal diffraction analysis. The cyclometallation of MCl2(Ph2P(CH2)5PPh2) (M = Pd, Pt) to give 1 and its Pt(II) analogue was probed using electrospray ionisation mass spectrometry (ESMS). The reactivity of 1 towards neutral ligands such as phosphines and pyridines as well as basic metal complexes such as pyridine-thiolate compounds of Au(I), Hg(II) and Pt(II) in solution was also investigated. The results showed that the chloride trans to the Pd–C bond is susceptible to ligand replacement. A number of entry metalloligands was examined in an attempt to establish a route to cyclometallated aggregates and clusters.

Redox condensation of PPN[Mn2(μ-PPh2)(CO)8] and PdCl2(η2-dppm) gives bimetallic PdMn(μ-PPh2)(μ-dppm)(CO)3(PPh3) (1) with an unexpected formation of PPh3. The latter can be displaced when 1 reacts with free diphosphines (dppm, dppe, dppf) giving PdMn(μ-PPh2)(μ-dppm)(CO)3(Ph2PXP(O)Ph2) (2, XCH2 (2a), C2H4 (2b), C5H4FeC5H4 (2c)) and [PdMn(CO)3(μ-PPh2)(μ-dppm)]2(μ-Ph2PXPPh2) (3a). Complexes 2 are “A-frame”-type bimetallic complexes with an syn-dppm bridging the MnPd bond. In contrast, complex 3a is a “double A-frame” anti-bridged by dppm. As a result, the latter is trans to the MnPd bonds. Both types of dppm bridges are substitutionally inert. Either bridging role is best served by dppm (and not dppe or dppf). The structures of the complexes were derived from NMR analyses of all complexes and X-ray single-crystal diffraction analyses of 1, 2a and 2b. The common and stable “A-frame”-type core in these bimetallics provides a thermodynamic driving force for the opposite transmetallation migration of phosphide and phosphine (dppm) when 1 is formed.

Although catalytically active palladium phosphine carboxylates are generally unstable, a series of such complexes are stabilized by dppf, viz. Pd(O2CR)2(dppf) [R=CF3 I, CF2CF3 II [1] , [43] CF2CF2CF3 III, CHCl2 IV, o-C6H4Cl VI, CH2CO2H VII, CHCHCO2H VIII]. They have been spectroscopically characterized and their structures determined by X-ray single-crystal crystallography. Two derivatives viz. Pd(O4C2-O,O′)(dppf) IX and PdCl(O2CPh)(dppf) X are included for comparison. They are invariably mononuclear with chelating phosphine and unidentate carboxylates. The more labile (and less basic) carboxylates tend to form complexes that are more resistive to reductive decomposition. Pd(O2CPh)2(dppf) V decomposes readily to PdCl2(dppf) in the presence of chlorinated solvents.

The bidentate ligand 1,1’-bis(diphenylphosphino)ferrocene (dppf) is a widely used component in catalytic systems and its role in this capacity has been expertly reviewed elsewhere. The focus of this Perspective is the increasing use of dppf in the synthesis and matrix of 21st century materials. The ferrocene core imparts fine control to catalytic C–C and C–X coupling reactions used to manufacture a range of functional macromolecules from tailored dyes and OLED components to precisely engineered conducting polymers and thermoplastics. This ligand's limited flexibility resembles a ball and socket joint with simultaneous rotation and constrained perpendicular freedom. This uniquely restricted range of movement stabilizes a diverse array of ground and transition states for these important transition metal catalysed coupling reactions. It may also contribute desirable mechanical or electronic functionality as a bridging or chelating component in a coordination array, metallocycle or larger supramolecular assembly. The ferrocene offers steric bulk and crystallinity to these materials aiding chemical stability and ease of handing. It's oxidizability assists characterization and may be tailored to provide or complement photo- or electroactivity. Dppf containing materials have been designed with diverse functions from cooperative luminescence to host–guest complexation. It is likely that this ubiquitous lab companion will increasingly find its way into the fabric or processing of future functional molecular materials.

Lithium-air batteries have become a focus of research on future battery technologies. Technical issues associated with lithium-air batteries, however, are rather complex. Apart from the sluggish oxygen reaction kinetics which demand efficient oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) catalysts, issues are also inherited from the nature of an open battery system and the use of reactive metal lithium as anode. Lithium-air batteries, which exchange oxygen directly with ambient air, face more challenges due to the additional oxidative agents of moisture, carbon dioxide, etc. which degrade the metal lithium anode, deteriorating the performance of the batteries. In order to improve the cycling performance one must hold a full picture of lithium-oxygen electrochemistry in the presence of carbon dioxide and/or moisture and fully understand the fundamentals of chemistry reactions therein. Recent advances in the exploration of the effect of moisture and CO2 contaminants on Li-O2 batteries are reviewed, and the mechanistic understanding of discharge/charge process in O2 at controlled level of moisture and/or CO2 are illustrated. Prospects for development opportunities of Li-air batteries, insight into future research directions, and guidelines for the further development of rechargeable Li-air batteries are also given.

This Review describes an important subclass of N-heterocyclic carbene complexes with thiazol-2-ylidenes ligands with only one exocyclic substituent on the thiazole ring. It highlights the synthetic, structural, and catalytic properties of these rapidly emerging complexes.

The cyclometallated Pd compound [upper bond 1 start]PdCl[PPh(2)CH(2)CH(2)C[upper bond 1 end]HCH(2)CH(2)PPh(2)], obtained from PdCl(2)(Ph(2)P(CH(2))(5)PPh(2)) in refluxing DMF (N,N-dimethylformamide), was characterized by NMR and X-ray single-crystal diffraction analysis. The cyclometallation of MCl(2)(Ph(2)P(CH(2))(5)PPh(2))(M = Pd, Pt) to give and its Pt(ii) analogue was probed using electrospray ionisation mass spectrometry (ESMS). The reactivity of towards neutral ligands such as phosphines and pyridines as well as basic metal complexes such as pyridine-thiolate compounds of Au(i), Hg(ii) and Pt(ii) in solution was also investigated. The results showed that the chloride trans to the Pd-C bond is susceptible to ligand replacement. A number of entry metalloligands was examined in an attempt to establish a route to cyclometallated aggregates and clusters.

Dr. N. Ding, Dr. D.-S. Geng, S.-W. Chien, Dr. T. An, Prof. T. S. A. Hor, Dr. Z.-L. Liu, Dr. Y. Zong Institute of Materials Research and Engineering (IMRE) A*STAR (Agency for Science, Technology and Research) 3 Research Link , Singapore 117602 , Republic of Singapore E-mail: zl-liu@imre.a-star.edu.sg; y-zong@imre.a-star.edu.sg Dr. S.-F. Chen, Prof. S.-H. Yu Division of Nanomaterials and Chemistry Hefei National Laboratory for Physical Sciences at Microscale Collaborative Innovation Center of Suzhou Nano Science and Technology, Department of Chemistry National Synchrotron Radiation Laboratory University of Science and Technology of China Hefei 230026 , P. R. China E-mail: shyu@ustc.edu.cn Prof. T. S. A. Hor Department of Chemistry National University of Singapore 3 Science Drive 3 , Singapore 117543 , Republic of Singapore

The bidentate ligand 1,1'-bis(diphenylphosphino)ferrocene (dppf) is a widely used component in catalytic systems and its role in this capacity has been expertly reviewed elsewhere. The focus of this Perspective is the increasing use of dppf in the synthesis and matrix of 21st century materials. The ferrocene core imparts fine control to catalytic C-C and C-X coupling reactions used to manufacture a range of functional macromolecules from tailored dyes and OLED components to precisely engineered conducting polymers and thermoplastics. This ligand's limited flexibility resembles a ball and socket joint with simultaneous rotation and constrained perpendicular freedom. This uniquely restricted range of movement stabilizes a diverse array of ground and transition states for these important transition metal catalysed coupling reactions. It may also contribute desirable mechanical or electronic functionality as a bridging or chelating component in a coordination array, metallocycle or larger supramolecular assembly. The ferrocene offers steric bulk and crystallinity to these materials aiding chemical stability and ease of handing. It's oxidizability assists characterization and may be tailored to provide or complement photo- or electroactivity. Dppf containing materials have been designed with diverse functions from cooperative luminescence to host-guest complexation. It is likely that this ubiquitous lab companion will increasingly find its way into the fabric or processing of future functional molecular materials.

This Review describes an important subclass of N-heterocyclic carbene complexes with thiazol-2-ylidenes ligands with only one exocyclic substituent on the thiazole ring. It highlights the synthetic, structural, and catalytic properties of these rapidly emerging complexes.