ChemSusChem最新文献

Electroreduction of carbon dioxide into value-added fine chemicals is a promising technique to realize the carbon cycle. Recently, metal-free heteroatom doped carbons are proposed as promising cost-effective electrocatalysts for CO2 reduction reaction (CO2RR). However, the lack of understanding of the active site prevents the realization of a high-performance electrocatalyst for the CO2RR. Herein, we synthesized metal-free N, P co-doped carbons (NPCs) for producing syngas, which is composed of H2 and CO, by CO2 electrolysis using inexpensive bio-based raw materials via simple pyrolysis. The syngas ratio (H2/CO) can be controlled within the high demand range (0.3-4) at low potentials using NPCs by tuning the N and P contents. In comparison with only N doping or P doping, N and P co-doping has a positive impact on improving CO2RR activity. Experimental analysis and density functional theoretical (DFT) calculations revealed that negatively charged C atoms adjacent to N and P atoms are the most favorable active sites for CO2-to-CO conversion compared to pyridinic N on N, P co-doped carbon. Introducing N atoms generates the preferable CO2 adsorption site, and P atoms contribute to decreasing the Gibbs free energy barrier for key *COOH intermediates adsorbed on the negatively charged C atoms.

The spread of point-of-care (PoC) diagnostic tests using electrochemical sensors poses a significant environmental challenge, especially in limited-resource settings due to the lack of waste management infrastructure. This issue is expected to intensify with the emergence of the Internet of Medical Things (IoMT), necessitating eco-friendly solutions for disposable devices. This review discusses efforts to develop green and sustainable PoC diagnostic devices, clarifying terms like biodegradability and transient electronics. It explores potential transient and biodegradable materials and fabrication technologies, emphasizing sustainable electronics with low-energy consumption and low-carbon footprint techniques, particularly favoring printing methods. The review highlights examples of necessary electronic components containing biodegradable materials for electrochemical PoC devices and discusses their role in device sustainability. Finally, it examines the feasibility of integrating these components and technologies into comprehensive biodegradable PoC devices, addressing the imminent need for eco-friendly solutions in diagnostic testing. This comprehensive discussion serves as a guide for researchers and developers striving to mitigate the environmental impact of PoC testing in the era of IoMT and personalized medicine.

Solid-state batteries (SSBs) present a potential pathway for advancing next-generation lithium batteries, characterized by exceptional energy density and enhanced safety performance. Solid-state electrolytes have been extensively researched, yet an affordable option with outstanding electrochemical performance is still lacking. In this work, Li4-xNaxTi5O12 (LNTO)-based composite solid electrolytes (CSEs) were developed to enhance the interface stability and electronic insulation. The CSE is composed of Li3.88Na0.12Ti5O12 (LNTO3) and poly (vinylidene fluoride) (PVDF) with a proportion of 20 wt.% exhibited high ionic conductivity (4.49 × 10-4 S cm-1 at a temperature value equal to 35 °C), high ionic transfer number (equal to 0.72), low activation energy (equal to 0.192 eV), and favorable compatibility with the Li metal anode. The Li|LNTO3|LiFePO4 cell, tested at a 0.5 C current density, demonstrated 154.5 mAh g-1 of outstanding cycling stability for 200 cycles, capacity retention of 97.6% along with a Coulombic efficiency of over 99%) as well as a significant average specific capacity of 127.8 mAh g-1 over 400 cycles at 5 C. This study offers an effective method for preparing commercial CSEs for SSBs.

The excessive emission and continuous accumulation of CO2 have precipitated serious social and environmental issues. However, CO2 can also serve as an abundant, inexpensive, and non-toxic renewable C1 carbon source for synthetic reactions. To achieve carbon neutrality and recycling, it is crucial to convert CO2 into value-added products through chemical pathways. Multi-carbon (C2+) products, compared to C1 products, offer a broader range of applications and higher economic returns. Despite this, converting CO2 into C2+ products is difficult due to its stability and the high energy required for C-C coupling. Cascade catalytic reactions offer a solution by coordinating active components, promoting intermediate transfers, and facilitating further transformations. This method lowers energy consumption. Recent advancements in cascade catalytic systems have allowed for significant progress in synthesizing C2+ products from CO2. This review highlights the features and advantages of cascade catalysis strategies, explores the synergistic effects among active sites, and examines the mechanisms within these systems. It also outlines future prospects for CO2 cascade catalytic synthesis, offering a framework for efficient CO2 utilization and the development of next-generation catalytic systems.

Oxygen evolution reaction is a pivotal anodic reaction for electrolysis, however, it remains the obstacle from its sluggish reaction kinetics originating from multiple electron transfer pathways at electrochemical interfaces. Especially, it remains a challenge to achieve stable operation at elevated current densities as electrodes suffer oxidative environment in corrosive conditions. Herein, we report that the conducting polymer polypyrrole electrodeposited Pr0.7Sr0.3CoO3 perovskite oxides for durable oxygen evolution electrodes. We found that the conducting polymer electrodeposited oxides exhibited a highly durable electrochemical oxygen evolution performance maintaining >99% of initial activities during the accelerated durability test. Meanwhile, bare metal oxides presented significant performance drops (<6% of initial activities) over the consecutive 20,000 accelerated durability test. High-resolution transmission electron microscope images identified the maintenance of high crystallinity of the heterostructure, suggesting that the electrodeposited pPy clusters can effectively delocalize highly polarized electrodes preventing material corrosion. The overall water electrolysis experiments further demonstrated that the heterostructure showed excellent stability at the high current density of 100 mA cm-2 over 700 hours. This marks the first report of the delocalized polarization benefiting from conducting polymers for durable oxygen evolution for perovskite oxides, suggesting great potential for scalable water electrolysis.

Developing polymers with labile bonds has attracted increasing attention since it can favor the chemical recycling into oligomers that could be recovered and re-used. Different chemical bonds can break upon exposure to external stimuli, such as thermal, UV, or chemical triggers. Among these, the acetal bond can degrade under mild acidic conditions. This study focuses on the synthesis of polymers constituted by acetal moieties suitable for triggered depolymerization. In particular, the solvent-less polyaddition of 1,4-butanediol and 1,4-butanediol divinyl ether was developed and optimized using a heterogeneous catalyst (Amberlyst 15) at 100 °C. The best conditions in terms of catalyst loading and reagent ratio were determined through a Design-of-Experiment aiming to achieve high conversion, low polydispersity, and desirable molecular weight. The resulting material presented an amorphous character and thermal stability up to 220 °C. It was confirmed responsive in an acidic environment, being completely hydrolyzed in 42 days, while remaining stable at neutral and basic pH. The obtained results represent a proof of concept for the design of pH-responsive materials through solventless, and scalable processes. The acetal moiety may be further exploited to achieve architectures presenting a sustainable end-of-life by implementing a recycling-by-design approach for new adhesives or degradable thermosetting materials.

pKa values of C-H bonds remain unreported and challenging in fluorous solvents because of these solvents' unique physicochemical properties, although they have been measured, theorized and predicted successfully in water and common organic solvents. Herein, a new CF3SO2-substituted anchor compound designed for matching the physicochemical properties of polar fluorinated arenes is synthesized. Its self-dissociation constants in these solvents are used as bases for experimentally determining the pKa values of 36 C-H compounds in them. These experimentally determined pKa values exhibit excellent linear free-energy relationships and correlate well with their corresponding DFT-calculated values. These data indicate that the polar fluorinated arenes are thermodynamically more favorable for deprotonation of ketone derivatives than acetonitrile as reaction media, resulting in enhanced deprotonation-promoted CO2 fixation. The pKa values determined in this work can be used as an important guidance tool for reactions involving the formation and cleavage of C-H bonds in polar fluorinated arenes.

An efficient Ni-based heterogeneous catalyst from pine needles urban waste valorization was designed and developed with a resource recycling strategy. The Ni/PiNe catalyst was fully characterized and tested in the Suzuki-Miyaura coupling under microwave irradiation. Although Ni is a promising candidate for replacing Pd-based catalytic systems, it generally requires a high catalyst amount and the exploitation of ligands and additives to enhance the reaction rate. On the contrary, with our new Ni/PiNe, 30 different products were efficiently synthesized with an isolated yield of up to 93%, using a very low catalyst amount and in the absence of ligands. Furthermore, the Ni/PiNe catalyst also showed good durability for consecutive cycles and an impressive TON value (1140). In addition to the catalytic efficiency in short reaction time and to the stability and durability under MW irradiation, the Ni/PiNe allowed for further optimization, achieving a low E-factor value (14.0), thus highlighting the potential in further reducing the waste and costs associated to the process.

Si-based anodes can increase specific energy and energy density of Li ion batteries. However, the volume-induced material stress and capacity loss necessitates only a partial Si utilization within composite anodes, typically with state-of-the-art graphite, so called Si/Gr composites. In this work, various Si nanowires (SiNWs), a promising Si architecture for these composites, are investigated and modified via pre-lithiation. Though, charged pre-lithiated anodes show potentials below 0 V vs. Li|Li+ in the initial cycles, they do not show indications for metallic Li, which is likely a hint for a triggered surface Li depletion in course of a continuous "transfer-lithiation" from lithiated Gr to Si, which is indicated by decreasing LiC6 and increasing LixSiy signals via nuclear magnetic resonance (NMR), X-ray diffraction (XRD) as well as shifts in capacities of respective voltage plateaus during discharge after storage. A relevant contribution of self-discharge is unlikely as shown by a stable open-circuit-voltage during storage in charged state and similar subsequent discharge capacities, being consequently also a hint for an intra-electrode capacity shift. The process of transfer lithiation is finally validated via solid-state 7Li NMR for varied Si morphology, i.e., amorphous and crystalline, as well as during pre-lithiation with passivated lithium metal powder (PLMP).

Surface-like diffusion is a recently proposed concept to explain the mechanism of ultrafast ionic conduction in high-rate oxide (e. g., niobium oxides and their alloys with TiO₂ and WO₃) and framework materials (e. g., Prussian blue analogs). This perspective seeks to illustrate the structural origin, theoretical foundation, and experimental evidences of surface-like diffusion. Unlike classical lattice diffusion, which typically involves ionic hopping between adjacent interstitial sites in solids, surface-like diffusion occurs when ions-that are significantly smaller than the interstitials-migrate along the off-center path in the diffusion channel. This mechanism results in an exceptionally low activation energy (E_a) down to 0.2 eV, which is crucial for achieving high-rate performance in electrochemical devices such as lithium-ion and sodium-ion batteries. This concept review also discusses the criteria to identify materials with potential surface-like diffusion and outlines theoretical and experimental tools to capture such phenomenon. Several candidates for further investigation are proposed based on the current understanding of the mechanism.