Biopolymers, especially cellulose, are vital to transitioning to a circular economy and reducing our reliance on fossil fuels. However, for many applications a high degree of cellulose hydroxyl modification is necessary. The challenge is that the chemical features of the hydroxyls of cellulose and water are similar. Therefore, chemical modification of cellulose is often explored under non-aqueous conditions with systems that result in high hydroxyl accessibility and reduce cellulose aggregation. Unfortunately, these systems depend on hazardous and complex solvents from fossil resources, which diverge from the initial sustainability objectives. To address this, we developed three new betaine-based ionic liquids that are fully bio-based, scalable, and green. We found that a specific ionic liquid had the perfect chemical features for the chemical activation of cellulose without disturbing its crystalline ordering. The high activation in heterogeneous conditions was exemplified by reacting cellulose with succinic anhydride, resulting in more than 30 % conversion of all hydroxyls on cellulose. Overall, this work opens new perspectives for the derivatization of cellulosic materials while simultaneously "keeping it green".

Highly selective degradation of polylactide (PLA) waste can be achieved through the use of supported-metal catalysts and molecular oxygen in water, process, known as “catalyst-controlled tandem hydrolysis-oxidation”, that offers a high flexibility and pathway-specific control. It is also scalable and operationally efficient, enabling complete conversion of PLA waste into valuable feedstocks such as pyruvic acid, acetic acid, or a mixture of acetic acid and formaldehyde through carbon upcycling.

Abstract

As plastic waste pollution continues to pose significant challenges to our environment, it is crucial to develop eco-friendly processes that can transform plastic waste into valuable chemical products in line with the principles of green chemistry. One major challenge is breaking down plastic waste into economically valuable carbon resources. This however presents an opportunity for sustainable circular economies. In this regard, a flexible approach is presented that involves the use of supported-metal catalysts to selectively degrade polylactide waste using molecular oxygen. This protocol has several advantages, including its operation under organic solvent-free and mild conditions, simplicity of implementation, and high atom efficiency, resulting in minimal waste. This approach enables the chemical upcycling of polylactide waste into valuable chemicals such as pyruvic acid, acetic acid, or a mixture containing equimolar amounts of acetic acid and formaldehyde, providing a viable alternative for accessing key value-added feedstocks from waste and spent plastics.

Interface, especially the electrochemically formed solid electrolyte interphase (SEI), is significantly important for cycling stability, reaction kinetics and safety of rechargeable batteries. In order to construct ideal SEI, the fundamental understanding of the SEI and EDL at the molecular level and interfacial chemistry is required. However, as far as we know, there is no review to demonstrate the theme specially. Herein, the recent substantial progress for EDL and its impact on the formation of SEI in rechargeable batteries are reviewed and discussed.

Abstract

Interphases, especially the electrochemically formed solid electrolyte interphase (SEI), are significantly important for cycling stability, reaction kinetics and safety of rechargeable batteries. The structure and composition of the electric double layer (EDL) greatly affect the formation of the SEI and the performance of electrodes. However, as far as we know, there is no review discussing the theme specifically. Herein, the recent substantial progress for EDL and its impact on the formation of SEI in rechargeable batteries are reviewed and discussed. Firstly, the specific adsorption of electrolyte components on electrodes’ surface and the ionic solvation structure are introduced. Furthermore, various methods for controlling EDL in different electrode systems are described. Finally, the potential future advancements of the SEI through the manipulation of EDL are discussed, aiming to enhance the electrochemical performance of rechargeable batteries.

The nanowire arrays composed of RuNi alloy nanoparticles and MoC are fabricated. The fabricated nanowire arrays exhibit an overpotential of 366 mV at a current density of 500 mA cm⁻² with robust stability over 1000 h in the seawater, among the best OER catalysts reported to date.

Abstract

In alkaline seawater electrolysis, the oxygen evolution reaction (OER) is greatly suppressed by the occurrence of electrode corrosion due to the formation of hypochlorite. Herein, a catalyst consisting of MoC nanowires modified with NiFe alloy nanoparticles (NiFe/MoC) on nickel foam (NF) is prepared. The optimized catalyst can deliver a large current density of 500 mA cm⁻² at a very low overpotential of 366 mV in alkaline seawater, respectively, outperforming commercial IrO₂. Remarkably, an electrolyzer assembled with NiFe/MoC/NF as the anode and NiMoN/NF as the cathode only requires 1.77 V to drive a current density of 500 mA cm⁻² for alkaline seawater electrolysis, as well as excellent stability. Theory calculation indicates that the initial activity of NiFe/MoC is attributed to increased electrical conductivity and decreased energy barrier for OER due to the introduction of Fe. We find that the change of the catalyst in the composition occurred after the stability test; however, the reconstructed catalyst has an energy barrier close to that of the pristine one, which is responsible for its excellent long-term stability. Our findings provide an efficient way to construct high-performance OER catalysts for alkaline seawater splitting.

We report an unprecedented result of self-aggregation of [Pt(L1)Cl] (HL1 = 1,3-di(5-carboxy-2-pyridyl)benzene) triggered by CO2 in basic aqueous solution. The color of basic aqueous solution containing [Pt(L1)Cl] changes from yellow to blue-green during the aggregation resulted from a reaction with CO2 in air. Upon CO2 gas bubbling, strong and broad absorption bands of aggregate assigned to the metal-metal-to-ligand charge transfer transition appeared at 701 and 1152 nm. Recrystallization of [Pt(L1)Cl] from Na2CO3 aqueous solution afforded polymorphic crystals of red and blue-green forms. A single X-ray crystallography revealed that the red form of crystal consists of a Pt–Pt stacked dimer bridged by CO32– ion and one of the carboxy groups of L1 is deprotonated. An elemental analysis provided evidence that the blue-green crystal is constructed by linear array consisting of the [Pt(L2)(CO3)]3– (HL2 = 1,3-di(5-carboxylate-2-pyridyl)benzene) units. The formation process of blue-green aggregate in aqueous solution was monitored through a transient absorption spectrum, and the absorption of aggregates involved in the spectral change were examined by a global analysis. A singular value decomposition and kinetic analysis provide that there are four species resulted from the self-assembling reaction in the solution and the maximal degree of aggregation is at least 32-mer.

Poly(2,6-dimethyl-1,4-phenylene oxide) (PPO) is one of the most important engineering plastics commonly utilized in various fields. Herein, chemical recycling of PPO was performed via oxidative depolymerization to form 2,6-diemthyl-p-benzoquionone (26DMBQ) as a sole aromatic product in 66% yield using nitronium ions (NO2+) as a mild oxidant. Mechanistic studies revealed that PPO is oxidized by NO2+ generated from the combination of a silicotungstic acid and nitrate salts, and then subsequently attacked by H2O to achieve C–O bond cleavage, resulting in the formation of 26DMBQ, which was sublimed at the headspace of the reaction vessel in pure form. 26DMBQ was applied to polymerization with dianilines to form polyimides. Thus, an upgrade recycling process of PPO was demonstrated.

The solid-state electrolytes are keys to achieve high energy, safety and stability for lithium ion batteries. In this review, core indicators of solid polymer electrolytes are discussed in detail including ionic conductivity, interface compatibility, mechanical integrity and cycling stability. Besides, we have also summarized how above properties can be improved by the design strategy of functional monomers, groups and assembly of batteries. Structures and properties of polymers are investigated here to provide a basis for all-solid-state electrolyte design strategies of multi-component polymers. Meanwhile, adjustment strategies of quasi-solid-state polymer electrolytes such as adding functional additives and carrying out structural design have also been investigated, aiming at solving problems caused by simply adding liquids or small molecular plasticizer. We hope that fresh and established researchers can achieve a general perspective of solid polymer electrolytes via this review, and spur more extensive interests for exploration of high-performance lithium ion batteries.

Solar hydrogen production at a high efficiency holds the significant importance in the age of energy crisis, while the micro-environment manipulation of active sites on photocatalysts plays a profound role in enhancing the catalytic performance. In this work, a series of well-defined single-site Ni-grafted TiO2 photocatalysts with unique and specific coordination environments, 2,2'-bipyridine-Ni-O-TiO2 (T-Ni Bpy) and 2-Phenylpyridine-Ni-O-TiO2 (T-Ni Phpy), were constructed with the methods of surface organometallic chemistry combined with surface ligand exchange for visible-light-induced photocatalytic hydrogen evolution reaction (HER). A prominent rate of 33.82 μmol•g-1•h-1 and a turnover frequency of 0.451 h-1 for Ni are achieved over the optimal catalyst T-Ni Bpy for HER, 260-fold higher than those of Ni-O-TiO2. Fewer electrons trapped oxygen vacancies and a larger portion of long-lived photogenerated electrons (> 3 ns, ~ 52.9%), which were demonstrated by the electron paramagnetic resonance and femtosecond transient IR absorption, are corresponding to the photocatalytic HER activity over the T-Ni Bpy. The number of long-lived free electrons injected from the Ni photoabsorber to the conduction band of TiO2 is one of the determining factors for achieving the excellent HER activity.

Organic molecule bifunctionalized polymeric carbon nitride (MBCN) with edge-grafted and interchain-embedded benzene rings as the respective electron-donating group and charge-transfer channel exhibits significantly enhanced photocatalytic H₂O₂ production activity due to the promoted separation/transfer of photogenerated charge carriers and visible light absorbance. Based on density functional theory calculation and experimental results, we propose the transfer path of photogenerated electrons.

Abstract

Modifying the polymeric carbon nitride (CN) with organic molecules is a promising strategy to enhance the photocatalytic activity. However, most previously reported works show that interchain embedding and edge grafting of the organic molecule can hardly be achieved simultaneously. Herein, we successfully synthesized organic molecule bifunctionalized CN (MBCN) through copolymerization of melon and sulfanilamide at a purposely elevated temperature of 550 °C. In MBCN, the edge grafted and interchain embedded benzene rings act as the electron-donating group and charge-transfer channel, respectively, rendering efficient photocatalytic H₂O₂ production. The optimal MBCN exhibits a significantly improved non-sacrificial photocatalytic H₂O₂ generation rate (54.0 μmol g⁻¹ h⁻¹) from pure water, which is 10.4 times that of pristine CN. Experimental and density functional theory (DFT) calculation results reveal that the enhanced H₂O₂ production activity of MBCN is mainly attributed to the improved photogenerated charge separation/transfer and decreased formation energy barrier (▵G) from O²⁻ to the intermediate 1,4-endoperoxide (⋅OOH). This work suggests that simultaneous formation of electron donating group and charge transfer channel via organic molecule bifunctionalization is a feasible strategy for boosting the photocatalytic activity of CN.

An operando anion-exchange membrane fuel cell (AEMFC) was analyzed via artificial intelligence. Using impedance spectroscopy genetic programming (ISGP), we quantified the resistances of the various physical processes occurring in the system for the first time providing valuable information to the AEMFC community with wider applicability to other electrochemical process.

Abstract

The existing gap in the ability to quantify the impacts of resistive losses on the performance of anion-exchange membrane fuel cells (AEMFCs) during the lifetime of their operation is a serious concern for the technology. In this paper, we analyzed the ohmic region of an operating AEMFC fed with pure oxygen followed by CO₂-free air at various operating currents, using a combination of electrochemical impedance spectroscopy (EIS) and a novel technique called impedance spectroscopy genetic programming (ISGP). Presented here for the first time in this work, we isolated and quantified the individual effective resistance (R_eff) values occurring in the AEMFC and their influence on performance as operating conditions change. We believe that this first work is vital to help distinguish the influence of the individual catalytic and mass-transfer processes in this technology thereby providing valuable data to the AEMFC community, with potentially wider applicability to other electrochemical devices where individual physical processes occur simultaneously and need to be sequestered for deeper understanding.