A Hybrid Redox-Mediated Zinc-Air Fuel Cell for Scalable and Sustained Power Generation.

Zinc-air batteries (ZABs) have attracted considerable attention for their high energy density, safety, low noise, and eco-friendliness. However, the capacity of mechanically rechargeable ZABs was limited by the cumbersome procedure for replacing the zinc anode, while electrically rechargeable ZABs suffer from issues including low depth of discharge, zinc dendrite and dead zinc formation, and sluggish oxygen evolution reaction, etc. To address these issues, we report a hybrid redox-mediated zinc-air fuel cell (HRM-ZAFC) utilizing 7,8-dihydroxyphenazine-2-sulfonic acid (DHPS) as the anolyte redox mediator, which shifts the zinc oxidation reaction from the electrode surface to a separate fuel tank. This approach decouples fuel feeding and electricity generation, providing greater operation flexibility and scalability for large-scale power generation applications. The DHPS-mediated ZAFC exhibited a superior peak power density of 0.51 W/cm2 and a continuous discharge capacity of 48.82 Ah with ZnO as the discharge product in the tank, highlighting its potential for power generation.

High-Power Near-Neutral Aqueous All Organic Redox Flow Battery Enabled with a Pair of Anionic Redox Species.

Aqueous organic redox flow batteries (AORFBs) are regarded as a promising alternative for low-cost and durable grid-scale energy storage. However, the narrow potential gap, chemical lability and membrane fouling in most AORFBs constitute formidable roadblocks for practical applications. Herein, a pair of anionic organic molecules, namely (PPBPy)Br2 and PSS-TEMPO, are proposed. The (PPBPy)Br2 in anolyte reveals remarkable electrochemical stability without degradation after 1000 cycles, while PSS-TEMPO in catholyte presents a capacity decay rate as low as 0.012 %/cycle. At near-neutral conditions, the (PPBPy)Br2 /PSS-TEMPO flow cell exhibits a high voltage of 1.61 V, extremely low permeability across cation-exchange membrane and thus excellent cycling stability. Notably, a highest peak power density of 509 mW cm-2 has been achieved among reported all-organic aqueous RFBs. The molecular engineering strategies demonstrated here could provide a credible example of high-performance AORFBs.

Molecular engineering of dihydroxyanthraquinone-based electrolytes for high-capacity aqueous organic redox flow batteries.

Aqueous organic redox flow batteries (AORFBs) are a promising technology for large-scale electricity energy storage to realize efficient utilization of intermittent renewable energy. In particular, organic molecules are a class of metal-free compounds that consist of earth-abundant elements with good synthetic tunability, electrochemical reversibility and reaction rates. However, the short cycle lifetime and low capacity of AORFBs act as stumbling blocks for their practical deployment. To circumvent these issues, here, we report molecular engineered dihydroxyanthraquinone (DHAQ)-based alkaline electrolytes. Via computational studies and operando measurements, we initially demonstrate the presence of a hydrogen bond-mediated degradation mechanism of DHAQ molecules during electrochemical reactions. Afterwards, we apply a molecular engineering strategy based on redox-active polymers to develop capacity-boosting composite electrolytes. Indeed, by coupling a 1,5-DHAQ/poly(anthraquinonyl sulfide)/carbon black anolyte and a [Fe(CN)6]3-/4- alkaline catholyte, we report an AORFB capable of delivering a stable cell discharge capacity of about 573 mAh at 20 mA/cm2 after 1100 h of cycling and an average cell discharge voltage of about 0.89 V at the same current density.

Redox-Mediated Ambient Electrolytic Nitrogen Reduction for Hydrazine and Ammonia Generation.

This work presents a redox-mediated electrolytic nitrogen reduction reaction (RM-eNRR) using polyoxometalate (POM) as the electron and proton carrier which frees the TiO2 -based catalyst from the electrode and shifts the reduction of nitrogen to a reactor tank. The RM-eNRR process has achieved an ammonium production yield of 25.1 µg h-1 or 5.0 µg h-1 cm-2 at an ammonium concentration of 6.7 ppm. With high catalyst loading, 61.0 ppm ammonium was accumulated in the electrolyte upon continuous operation, which is the highest concentration detected for ambient eNRR so far. The mechanism underlying the RM-eNRR was scrutinized both experimentally and computationally to delineate the POM-mediated charge transfer and hydrogenation process of nitrogen molecule on the catalyst. RM-eNRR is expected to provide an implementable solution to overcome the limitations in the conventional eNRR process.

Decoupled Redox Catalytic Hydrogen Production with a Robust Electrolyte-Borne Electron and Proton Carrier.

Electrolytic water splitting is an effective approach for H2 mass production. A conventional water electrolyzer concurrently generates H2 and O2 in neighboring electrode compartments separated by a membrane, which brings about compromised purity, energy efficiency, and system durability. On the basis of distinct redox electrochemistry, here, we report a system that enables the decoupling of both the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) from the electrodes to two spatially separated catalyst bed reactors in alkaline solutions. Through a pair of close-loop electrochemical-chemical cycles, the system operates upon 7,8-dihydroxy-2-phenazinesulfonic acid (DHPS) and ferricyanide-mediated HER and OER, respectively, on Pt/Ni(OH)2 and NiFe(OH)2 catalysts. Near unity faradaic efficiency and sustained production of hydrogen has been demonstrated at a current density up to 100 mA/cm2. The superior reaction kinetics, particularly the HER reaction mechanism of DHPS as a robust electrolyte-borne electron and proton carriers, were scrutinized both computationally and experimentally. We anticipate the system demonstrated here would provide an intriguing alternative to the conventional water electrolytic hydrogen production.

Single-Molecule Redox-Targeting Reactions for a pH-Neutral Aqueous Organic Redox Flow Battery.

Aqueous organic redox flow batteries (AORFBs) have received considerable attention for large-scale energy storage. Quinone derivatives, such as 9,10-anthraquinone-2,7-disulphonic acid (2,7-AQDS), have been explored intensively owing to potentially low cost and swift reaction kinetics. However, the low solubility in pH-neutral electrolytes restricts their application to corrosive acidic or caustic systems. Herein, the single molecule redox-targeting reactions of 2,7-AQDS anolyte are presented to circumvent its solubility limit in pH-neutral electrolytes. Polyimide was employed as a low-cost high-capacity solid material to boost the capacity of 2,7-AQDS electrolyte to 97 Ah L-1 . Through in situ FTIR spectroscopy, a hydrogen-bonding mediated reaction mechanism was disclosed. In conjunction with NaI as catholyte and nickel hexacyanoferrate as the catholyte capacity booster, a single-molecule redox-targeting reaction-based full cell with energy density up to 39 Wh L-1 was demonstrated.

Synthesis of deuterium-labelled analogues of NLRP3 inflammasome inhibitor MCC950.

This study describes the syntheses of di, tetra and hexa deuterated analogues of the NOD-like receptor pyrin domain-containing protein 3 (NLRP3) inflammasome inhibitor MCC950. In di and tetra deuterated analogues, deuteriums were incorporated into the 1,2,3,5,6,7-hexahydro-s-indacene moiety, whereas in the hexa deuterated MCC950 deuteriums were incorporated into the 2-(furan-3-yl)propan-2-ol moiety. The di deuterated MCC950 analogue was synthesised from 4-amino-3,5,6,7-tetrahydro-s-indacen-1(2H)-one 5. Tetra deuterated analogues were synthesised in 10 chemical steps starting with 5-bromo-2,3-dihydro-1H-inden-1-one 9, whereas the hexa deuterated analogue was synthesised in four chemical steps starting with ethyl-3-furoate 24. All of the compounds exhibited similar activity to MCC950 (IC50 = 8 nM). These deuterated analogues are useful as internal standards in LC-MS analyses of biological samples from in vivo studies.

Hydroxyapatite-intertwined hybrid nanofibres for the mineralization of osteoblasts.

Advances in tissue engineering have enabled the development of bioactive composite materials to generate biomimetic nanofibrous scaffolds for bone replacement therapies. Polymeric biocomposite nanofibrous scaffolds architecturally mimic the native extracellular matrix (ECM), delivering tremendous regenerative potential for bone tissue engineering. In the present study, biocompatible poly(l-lactic acid)-co-poly(ε-caprolactone)-silk fibroin-hydroxyapatite-hyaluronic acid (PLACL-SF-HaP-HA) nanofibrous scaffolds were fabricated by electrospinning to mimic the native ECM. The developed nanofibrous scaffolds were characterized in terms of fibre morphology, functional group, hydrophilicity and mechanical strength, using SEM, FTIR, contact angle and tabletop tensile-tester, respectively. The nanofibrous scaffolds showed a higher level of pore size and increased porosity of up to 95% for the exchange of nutrients and metabolic wastes. The fibre diameters obtained were in the range of around 255 ± 13.4-789 ± 22.41 nm. Osteoblasts cultured on PLACL-SF-HaP-HA showed a significantly (p < 0.001) higher level of proliferation (53%) and increased osteogenic differentiation and mineralization (63%) for the inclusion of bioactive molecules SF-HA. Energy-dispersive X-ray analysis (EDX) data proved that the presence of calcium and phosphorous in PLACL-SF-HaP-HA nanofibrous scaffolds was greater than in the other nanofibrous scaffolds with cultured osteoblasts. The obtained results for functionalized PLACL-SF-HaP-HA nanofibrous scaffolds proved them to be a potential biocomposite for bone tissue engineering. Copyright © 2015 John Wiley & Sons, Ltd.

Identification, Synthesis, and Biological Evaluation of the Major Human Metabolite of NLRP3 Inflammasome Inhibitor MCC950.

MCC950 is an orally bioavailable small molecule inhibitor of the NOD-like receptor pyrin domain-containing protein 3 (NLRP3) inflammasome that exhibits remarkable activity in multiple models of inflammatory disease. Incubation of MCC950 with human liver microsomes, and subsequent analysis by HPLC-MS/MS, revealed a major metabolite, where hydroxylation of MCC950 had occurred on the 1,2,3,5,6,7-hexahydro-s-indacene moiety. Three possible regioisomers were synthesized, and coelution using HPLC-MS/MS confirmed the structure of the metabolite. Further synthesis of individual enantiomers and coelution studies using a chiral column in HPLC-MS/MS showed the metabolite was R-(+)- N-((1-hydroxy-1,2,3,5,6,7-hexahydro-s-indacen-4-yl)carbamoyl)-4-(2-hydroxypropan-2-yl)furan-2-sulfonamide (2a). Incubation of MCC950 with a panel of cytochrome P450 enzymes showed P450s 2A6, 2C9, 2C18, 2C19, 2J2, and 3A4 catalyze the formation of the major metabolite 2a, with a lower level of activity shown by P450s 1A2 and 2B6. All of the synthesized compounds were tested for inhibition of NLRP3-induced production of the pro-inflammatory cytokine IL-1ß from human monocyte derived macrophages. The identified metabolite 2a was 170-fold less potent than MCC950, while one regioisomer had nanomolar inhibitory activity. These findings also give first insight into the SAR of the hexahydroindacene moiety.