The increasing global energy consumption has led to the rapid development of renewable energy storage technologies. Lithium-ion batteries (LIBs) have been extensively studied and utilized for reliable, efficient, and sustainable energy storage. Nevertheless, designing new materials for LIB applications with high capacity and long-term stability is highly desired but remains a challenging task. Recently, covalent organic frameworks (COFs) have emerged as superior candidates for LIB applications due to their high porosity, well-defined pores, highly customizable structure, and tunable functionalities. These merits enable the preparation of tailored COFs with predesigned redox-active moieties and suitable porous channels that can improve the lithium-ion storage and transportation. This review summarizes the recent progress in the development of COFs and their composites for a variety of LIB applications, including (quasi) solid-state electrolytes, electrode materials, and separators. Finally, the challenges and potential future directions of employing COFs for LIBs are also discussed, further promoting the foundation of this class of exciting materials for future advances in energy-related applications.

P-type metal oxides, and in particular NiO, are typically used as hole accepting layers in dye-sensitized photocathodes. Delafossites (CuMO2) with M=B, Al, Cr or Ga have recently been proposed as attractive substitutes for NiO, with theoretically a higher hole mobility than NiO, and therefore allowing a higher efficiency when the photocathode is applied in solar to fuel devices. We have experimentally validated the photoelectrochemical performance of photocathodes consisting of nanoporous CuBO2 (CBO) on Fluorine-doped Tin Oxide substrates, photosensitized with a light absorbing P1 dye. Femtosecond transient absorption and time-resolved photoluminescence studies show that light-induced hole injection occurs from the P1 dye into the CBO in a few ps, comparable to the time constant observed for NiO-based photocathodes. Importantly, the CBO-based photocathode shows significantly slower charge recombination than the NiO-based analogue. These results illustrate the promise of CBO as a p-type semiconductor in solar energy conversion devices.

Climate change and the demand for clean energy have challenged scientists worldwide to produce/store more energy to reduce carbon emissions. This work proposes a conductive gel biopolymer electrolyte to support the sustainable development of high-power aqueous supercapacitors. The gel uses saline water and seaweed as sustainable resources. Herein, a biopolymer agar‒agar, extracted from red algae, is modified to increase gel viscosity up to 17-fold. This occurs due to alkaline treatment and an increase in the concentration of the agar‒agar biopolymer, resulting in a strengthened gel with cohesive superfibres. The thermal degradation and agar modification mechanisms are explored. The electrolyte is applied to manufacture sustainable and flexible supercapacitors with satisfactory energy density (0.764 W h kg-1) and power density (230 W kg-1). As an electrolyte, the aqueous gel promotes a long device cycle life (3500 cycles) for 1 Ag-1, showing good transport properties and low cost of acquisition and enabling the supercapacitor to be manufactured outside a glove box. These features decrease the cost of production and favor scale-up. To this end, this work provides eco-friendly electrolytes for the next generation of flexible energy storage devices.

Abio/bio hybrids, which incorporate biocatalysts that promote efficient and selective material conversions under mild conditions into existing catalytic reactions, have attracted considerable attention for developing new catalytic systems. This study constructed a H2-forming biocathode based on a carbon material combined with whole-cell biocatalysis of genetically-engineered‒hydrogenase-overproducing Escherichia coli for the photoelectrochemical water splitting for clean H2 production. Low-cost and abundant carbon materials are generally not suitable for H2-forming cathode due to their high overpotential for proton reduction; however, the combination of the reduction of an organic electron mediator on the carbon electrode and the H2 formation with the reduced mediator by the redox enzyme hydrogenase provides a H2-forming cathodic reaction comparable to that of the noble metal electrode. The present study demonstrates that the recombinant E. coli whole cell can be employed as a part of the H2-forming biocathode system, and the biocathode system wired with TiO2 photoanode can be a photoelectrochemical water-splitting system without external voltage assistance under natural pH. The findings of this study expand the feasibility of applications of whole-cell biocatalysis and contribute to obtaining solar-to-chemical conversions by abio/bio hybrid systems, especially for low-cost, noble-metal-free, and clean H2 production.

A new class of basic aqueous sorbents for CO₂ based on zwitterions that present environmental and safety advantages that significantly reduce the risks of possible human and environmental contamination and they may be used in the nowadays employed amine scrubbing industrial plants with little or no modifications.

Abstract

The zwitterions resulting from the covalent attachment of 3- or 4-hydroxy benzene to the 1,3-dimethylimidazolium cation represent basic compounds (pKa of 8.68 and 8.99 in aqueous solutions, respectively) that chemisorb in aqueous solutions 0.58 mol/mol of carbon dioxide at 1.3 bar (absolute) and 40 °C. Equimolar amounts of chemisorbed CO₂ in these solutions are obtained at 10 bar and 40 °C. Chemisorption takes place through the formation of bicarbonate in the aqueous solution using imidazolium-containing phenolate. CO₂ is liberated by simple pressure relief and heating, regenerating the base. The enthalpy of absorption was estimated to be −38 kJ/mol, which is about 30 % lower than the enthalpy of industrially employed aqueous solutions of MDEA (estimated at −53 kJ/mol using the same experimental apparatus). The physisorption of CO₂ becomes relevant at higher pressures (>10 bar) in these aqueous solutions. Combined physio- and chemisorption of up to 1.3 mol/mol at 40 bar and 40 °C can be attained with these aqueous zwitterionic solutions that are thermally stable and can be recycled at least 20 times.

Li₃VO₄ for lithium ion batteries: Lithium polyacrylate (LiPAA) worked as a dual-functional source and in-situ polymerized on the surface of Li₃VO₄ precursors through a spray-drying method. The obtained porous spherical Li₃VO₄ exhibits high specific capacities, excellent long cycling stability and enhanced rate capability.

Abstract

Li₃VO₄ is a promising anode material for use in lithium-ion batteries, however, the conventional synthesis methods for Li₃VO₄ anodes involve the separate use of lithium and carbon sources, resulting in inefficient contact and low crystalline quality. Herein, lithium polyacrylate (LiPAA) was utilized as a dual-functional source and an in-situ polymerization followed by a spray-drying method was employed to synthesize Li₃VO₄. LiPAA serves a dual purpose, acting as both a lithium source to improve the crystal process and a carbon source to confine the particle size within a desired volume during high-temperature treatment. Additionally, the in-situ synthesis of a porous carbon decorating skeleton prevents the growth and agglomeration of Li₃VO₄ particles and provides abundant ion/electron diffusion channels and contact areas. Based on the synthesis route and the constructed primary-secondary structure, the Li₃VO₄ anodes obtained in this study exhibit an impressive capacity of 596.2 mAh g⁻¹. Moreover, they demonstrate enhanced rate performance over 600 cycles during 10 periods of rate testing, as well as a remarkably long lifespan of 5000 cycles at high currents. The utilization of LiPAA as a dual-functional source represents a broad approach that holds great potential for future research on high-performance electrodes requiring both lithium and carbon sources.

Single−atom catalysts (SACs) have attracted wide attentions to be acted as potential electrocatalysts for nitrogen reduction reaction (NRR). However, the coordination environment of the single transition metal (TM) atoms is essential to the catalytic activity for NRR. Herein, we proposed four types of 3-, 4-coordinated and π−d conjugated TMxB3N3S6 (x = 2, 3, TM = Ti, V, Cr, Mn, Fe, Zr, Nb, Mo, Tc, Ru, Hf, Ta, W, Re and Os) monolayers for SACs. Based on density functional theory (DFT) calculations, I-TM2B3N3S6 and III-TM3B3N3S6 are the reasonable 3-coordinated and 4-coordinated structures screening by structure stable optimizations, respectively. Next, the structural configurations, electronic properties and catalytic performances of 30 kinds of the 3-coordinated I-TM2B3N3S6 and 4-coordinated III-TM3B3N3S6 monolayers with different single transition metal atoms were systematically investigated. The results reveal that B3N3S6 ligand is an ideal support for TM atoms due to existence of strong TM−S bonds. The 3-coordinated I-V2B3N3S6 is the best SAC with the low limiting potential (UL) of −0.01 V, excellent stability (Ef = −0.32 eV, Udiss = 0.02 V) and remarkable selectivity characteristics. This work not only provides novel π−d conjugated SACs, but also gives theoretical insights into their catalytic activities and offers reference for experimental synthesis.

A versatile post-synthetic modification strategy to functionalize a high surface area microporous network (MPN-OH) by bioorthogonal inverse electron-demand Diels-Alder (IEDDA) ligation is presented. While the polymer matrix is modified with a readily accessible norbornene isocyanate (Nb-NCO), a set of functional entities, presenting the robust asymmetric 1,2,4,5-tetrazine (Tz) allows easy functionalization of the MPN by chemoselective Nb/Tz ligation. A generic route is demonstrated, modulating the internal interfaces by introducing carboxylates, amides or amino acids as well as an oligopeptide d-Pro-Pro-Glu organocatalyst. The MPN-Peptide construct largely retains the catalytic activity and selectivity in an enantioselective enamine catalysis, proving remarkable availability in different solvents, offers heterogeneous organocatalysis in bulk and shows stability in recycling settings.

A series of cross-linked AEMs (c-DQPPO/PVA) are synthesized by using rigid polyphenylene oxide and flexible poly(vinyl alcohol) as the backbones. Dual cations are grafted on the PPO backbone to improve the ion exchange capacity (IEC), while glutaraldehyde is introduced to enhance compatibility and reduce swelling ratio of AEMs. In addition to the enhanced mechanical properties resulting from the rigid-flexible cross-linked network, c-DQPPO/PVA AEMs also exhibit impressive ionic conductivity, which can be attributed to their high IEC, good hydrophilicity of PVA, and well-defined micro-morphology. Additionally, due to confined dimension behavior and ordered micro-morphology, c-DQPPO/PVA AEMs demonstrate excellent chemical stability. Specifically, c-DQPPO/PVA-7.5 exhibits a wet-state tensile strength of 12.5 MPa and an elongation at break of 53.0% at 25 oC. Its OH− conductivity and swelling degree at 80 oC are measured to be 125.7 mS cm-1 and 8.2%, respectively, with an IEC of 3.05 mmol g-1. After 30 days in a 1 M NaOH solution at 80 oC, c-DQPPO/PVA-7.5 experiences degradation rates of 12.8% for tensile strength, 27.4% for elongation at break, 14.7% for IEC, and 19.2% for ion conductivity. With its excellent properties, c-DQPPO/PVA-7.5 exhibits a peak power density of 0.751 W cm-2 at 60 oC in an H2-O2 fuel cell.

The hydrogenation of biomass-derived furan compounds provides a sustainable pathway for the production of various valuable chemicals; product selectivity among multiple reaction pathways of furan compound hydrogenation is crucially dependent on catalytic sites; however controlling reaction pathways remains great challenging due to the lack of identification and understanding of active sites. In this work we reveal the role of base sites in furfural selective hydrogenation through deliberately designed and synthesized reversed catalysts, basic metal oxides and hydroxide on Cu. It is demonstrated that base species greatly enhanced the selectivity of 1, 2-pentanediol (1, 2-PeD) from furfural, presenting a nearly fourfold increase of 1, 2-PeD: methyl furan ratio over the Cu based reverse catalysts. A combination of infrared spectroscopy and DFT calculations demonstrates the strong interaction between the C-O-C bond in furan ring and the catalyst surface in preferentially parallel adsorption mode in the presence of base species on Cu, thus facilitating the activation of C-O-C bond to produce 1, 2-PeD. This work provides a strategy of designing reversed catalyst to study the effect of promoters and reveals the role of base sites in the hydrogenation of biomass-derived furan compounds to diols.