Simultaneous Oxidative Cleavage of Lignin and Reduction of Furfural via Efficient Electrocatalysis by P-Doped CoMoO4

Efficient cleavage of CO bond of lignin by synergistic electrocatalysis using a polyoxometalate catalyst with bimetallic sites

This study reported a low-cost and highly efficient Dexter-Silverton polyoxometalate (POM)/Ni foam composite (NiCo-POM/NF) with bimetallic sites for acetophenone production. With this novel composite as an electrocatalyst, β-O-4 in 2-phenoxy-1-phenylethanol (PPE), a typical β-O-4 model, can be selectively oxidized to aromatic chemicals with excellent yields (62 %-74 %) by controlled-potential electrolysis. A PPE conversion of 99.3 % and an acetophenone yield of 36.0 % were achieved from the electrochemical oxidation of PPE at 1.24 V vs. RHE in a deep eutectic solvent (DES). Moreover, real lignin can be effectively cleaved to yield the main products guaiacol and vanillin with the help of the proposed catalyst. In short, the Ni catalyst has excellent catalytic effect on the conversion of the lignin model compound and lignin. The incorporation of Co in POM strengthened adsorption on the substrate and added high-valence active sites, thus significantly improving the oxidation performance of the catalyst. In the bimetallic electrocatalyst with multiple active sites, Co3+/Co2+ served as an electron transfer mediator (ETM), while the Mo6+ acted as an electron donor for CO oxidative cleavage of PPE. This work provides an effective strategy for catalyst design as well as electrocatalytic valorization of biomass.

Electrocatalytic Lignin Valorization via Enhanced H₂O₂ Generation Using a MWNCT-Modified Gas Diffusion Electrode

The electrocatalytic valorization of lignin provides a sustainable route to valuable chemicals under mild conditions, yet achieving high efficiency and selectivity remains challenging. Here, we develop gas diffusion electrodes (GDEs) modified with few-layer graphene (GR) and multi-walled carbon nanotubes (MWCNT) to enhance the oxygen reduction reaction (ORR) for efficient hydrogen peroxide (H2O2) generation. The MWCNT-modified GDE exhibits the highest surface area and conductivity, achieving over 80 % selectivity for H2O2 via the two-electron ORR pathway. Electrochemical lignin depolymerization using this optimized GDE yields 72.3 % low-molecular-weight aromatic compounds within 1 h. The MWCNT-GDE demonstrates exceptional durability, maintaining stable performance across ten consecutive cycles. This work highlights the potential of MWCNT-modified electrodes to advance scalable electrochemical lignin valorization through in-situ H2O2 generation.

Biomass Valorization via Paired Electrocatalysis

Electrochemical valorization of biomass represents an emerging research frontier, capitalizing on renewable feedstocks to mitigate carbon emissions. Traditional electrochemical approaches often suffer from energy inefficiencies due to the requirement of a second electrochemical conversion at the counter electrode which might generate non-value-added byproducts. This review article presents the advancement of paired electrocatalysis as an alternative strategy, wherein both half-reactions in an electrochemical cell are harnessed to concurrently produce value-added chemicals from biomass-derived feedstocks, potentially doubling the Faradaic efficiency of the whole process. The operational principles and advantages of different cell configurations, including 1-compartment undivided cells, H-type cells, and flow cells, in the context of paired electrolysis are introduced and compared, followed by the analysis of various catalytic strategies, from catalyst-free systems to sophisticated homogeneous and heterogeneous electrocatalysts, tailored for optimized performance. Key substrates, such as CO2, 5-hydroxymethylfurfural (HMF), furfural, glycerol, and lignin are highlighted to demonstrate the versatility and efficacy of paired electrocatalysis. This work aims to provide a clear understanding of why and how both cathode and anode reactions can be effectively utilized in electrocatalytic biomass valorization leading to innovative industrial scalability.

Anion modulation enhances the internal electric field of CuCo2O4 to improve the catalysis in ammonia borane hydrolysis

Ammonia borane (NH3BH3, AB) is considered a promising chemical hydrogen storage material. The development of efficient, stable, and economical catalysts for AB hydrolysis is essential for realizing the hydrogen energy economy. In this study, a series of p-p heterojunction catalysts, labeled M (P/S/Cl)-CuCo2O4, were fabricated using the high-temperature vapor phase method to achieve anionic interface gradient doping. Due to the differences in electronegativity among the anions P/S/Cl-O, electron-rich and electron-deficient regions are generated at the interface, inducing the formation of local p-p heterojunctions with built-in electric fields (BIEF). The difference in work function (ΔWf) at the interface enhances the strength of the BIEF. Because of the positive influence of the BIEF on the adsorption of intermediates and interfacial behavior, the catalytic performance of P-CuCo2O4, characterized by a hydrogen evolution rate (HER) of 1125 mLH2(gcat·min)-1, is significantly higher than that of intrinsic CuCo2O4, which has an HER of 705 mLH2(gcat·min)-1. Its apparent activation energy of only 32.25 kJ/mol is superior to that of previous non-precious metal catalysts. Density functional theory (DFT) further confirms that the construction and enhancement of the BIEF can reduce the band gap, accelerate electron transfer, regulate the metal d-band center, and enhance the adsorption of AB and H2O molecules. This process facilitates the elongation and breakage of the O-H bond length in H2O and the B-H bond length in AB, thereby promoting the release of H2.

Molecular Weight Engineering Modulates Lignin-Metal Supramolecular Framework to Construct Carbon-Coated CoRu Alloy for Effective Overall Water Splitting

To overcome the challenges of low catalytic activity and instability, a molecular weight engineering strategy coupled with oxidative ammonolysis is developed to synthesize CoRu-based alloy catalysts with distinct morphologies and properties from biorefinery lignin. This approach effectively modulates intrinsic active sites and exposes unsaturated nitrogen-oxygen structures, thereby tailoring the morphology and defect structure of the carbon layers in the catalysts. The as-synthesized CoRu alloy catalysts from lignin precursors with varying molecular weights are designated as CoRu@OALC-EtOAC, CoRu@OALC-EtOH, and CoRu@OALC-Residual. CoRu@OALC-EtOAC, featuring a defect-rich graphitic carbon-coated CoRu alloy structure, exhibited exceptional overall water-splitting performance (1.48 V at 10 mA cm-2), significantly surpassing Pt/C || Ru/C (1.58 V at 10 mA cm-2). In contrast, CoRu@OALC-Residual, with its amorphous carbon-coated CoRu alloy structure, demonstrated remarkable stability (350 h at 100 mA cm-2), vastly outperforming Pt/C || Ru/C (6 h at 100 mA cm-2). In-situ Raman spectroscopy and DFT calculations revealed that the defect-rich carbon layers effectively adsorb *H intermediates, accelerating the catalytic process. This strong adsorption also induces carbon layer rearrangement, leading to its dissolution of the carbon layer and oxidation of CoRu metal particles. This strategy provides a universal method for biomass-derived catalysts, establishing a direct relationship between molecular weight, catalyst morphology, and electrocatalytic performance.

Crystal reconstructed cubic nickel oxide with energetic reactive interfaces for exceptional electrochromic smart windows

Electrochromic smart windows can realize intelligent photothermal regulation by applying a low potential, which is of great significance for energy-saving buildings and achieving low carbon emission. However, the dense structure of conventional metal oxide electrochromic materials limits ion transport efficiency, resulting in poor electrochromic properties. Here, we propose a surface crystal reconstruction strategy for cubic NiO through phosphorylation (P-NiO) to build energetic reactive interfaces and enhance the electrochromic performance. Theoretical simulations and experiments reveal that the introduction of PO4 tetrahedra tailored the crystal structure of cubic NiO, which endows it with a large number of contiguous intracrystal cavities and unsaturated P-O bonds on the surface. The energetic reactive interface optimizes the transport path of OH- and gets rid of the dependence on K+ in the adsorption process, thus improving the reaction kinetics of NiO. The P-NiO film delivers a large optical modulation (90.3%, at 500 nm), a high coloration efficiency (81.1 cm2 C-1, at 500 nm), and a fast switching speed (6 s and 7.2 s for coloring and bleaching processes). Furthermore, a model of an electrochromic smart window was fabricated based on the P-NiO film, using which a potential energy saving of 60.81 MJ m-2 and CO2 emission reduction of 11.98 kg m-2 can be achieved in hot climate zones according to energy simulations. The in-depth insights gained into the fundamental mechanism of this surface crystal reconstruction strategy will facilitate the rational design of high-performance electrochromic and electrochemical materials.

Enhancing selectivity of β-O-4 bond cleavage for lignin depolymerization via a sacrificial anode

Herein, we report a novel electrochemical hydrogenolysis method for β-O-4 bond cleavage by using carbon foam as the cathode and waste aluminum as the anode. The reaction takes place at the cathode, producing ketones and phenolic compounds. Employing waste aluminum as the anode could avoid anodic excessive oxidation of phenols.

Visible Light-Switchable Lattice Oxygen Sites for Selective C-H and C(O)-C Bond Electrooxidation

Lattice-oxygen is highly oxidizable, ideal for electrocatalytic C-H oxidation but insufficient alone for C(O)-C bond cleavage due to the non-removable nature of lattice sites. Here, we present a visible light-assisted electrochemical method of in situ formulating removable lattice-oxygen sites in a nickel-oxyhydroxide (ESE-NiOOH) electrocatalyst. This catalyst efficiently converts aromatic alcohols and carbonyls with C(O)-C fragments from lignin and plastics into benzoic acids (BAs) with high yields (83-99 %). Without light irradiation, ESE-NiOOH's intrinsic lattice-oxygen is non-removable and inert for C(O)-C bond cleavage. In situ characterizations show light-induced lattice-oxygen removal and regeneration via OH- refilling. Theoretical calculations identify the nucleophilic oxygen attack on ketone-derived carbanion as a rate-determining step, which can be remarkably facilitated by removable lattice-oxygen to activate α-C-H bonds. As a proof-of-concept, an "electrochemical funnel" strategy is developed for high-efficiency upgrading aromatic mixtures with C(O)-C moieties into BA with up to 94 % yield. This in situ removal-regeneration approach for lattice sites opens an avenue for the tailored design of interfacial electrocatalysts to selectively upcycle waste carbon sources into valuable products.

P-doped RuSe2 on Porous N-Doped Carbon Matrix as Catalysts for Accelerated Sulfur Redox Reactions

Monocomponent catalysts exhibit the limited catalytic conversion of polysulfides due to their intrinsic electronic structure, but their catalytic activity can be improved by introducing heteroatoms to regulate its electronic structure. However, the rational selection principles of doping elements remain unclear. Here, we are guided by theoretical calculations to select the suitable doping elements based on the balanced relationship between the adsorption strength of lithium polysulfides (LiPSs) and catalytic activity of lithium sulfide. We apply the screening method to develop a new catalyst of phosphorus doped RuSe2, manifesting the further enhanced conductivity compared with original RuSe2, facilitating charge transfer and further modulating the d-band center of RuSe2, thereby augmenting its effectiveness in interacting with LiPSs. Consequently, the assembled cell exhibits an areal capacity of 7.7 mAh cm-2, even under high sulfur loading of 8.0 mg cm-2 and a lean electrolyte condition (5.0 μL mg-1). This rational screening strategy offers a robust solution for the design of advanced catalysts in the field of lithium-sulfur batteries and potentially other domains as well.

Recent Progress in Electrocatalytic Conversion of Lignin: From Monomers, Dimers, to Raw Lignin

Lignin, as the second largest renewable biomass resource in nature, has increasingly received significant interest for its potential to be transformed into valuable chemicals, potentially contributing to carbon neutrality. Among different approaches, renewable electricity-driven biomass conversion holds great promise to substitute a petroleum resource-driven one, owing to its characteristics of environmental friendliness, high energy efficiency, and tunable reactivity. The challenges lie on the polymeric structure and complex functional groups in lignin, requiring the development of efficient electrocatalysts for lignin valorization with enhanced activity and selectivity toward targeted chemicals. In this Review, we focus on the advancement of electrocatalytic valorization of lignin, from monomers, to dimers and to raw lignin, toward various value-added chemicals, with emphasis on catalyst design, reaction innovation, and mechanistic study. The general strategies for catalyst design are also summarized, offering insights into enhancing the activity and selectivity. Finally, challenges and perspectives for the electrocatalytic conversion of lignin are proposed.

Multimetal synergy in an iron-cobalt-nickel hydroxide electrocatalyst for electro-oxidative lignin depolymerization to produce value-added aromatic chemicals

A ternary iron-cobalt-nickel hydroxide nanoarray catalyst was fabricated, which achieves enhanced performance towards electro-oxidative depolymerization of lignin models to produce benzoic acid and phenol.

Trifunctional phosphorus-doped cobalt molybdate catalyst in self-driven coupling systems for synchronized sulfur recovery and hydrogen evolution

This study introduces a self-driven system that effectively achieves synchronized sulfur recovery and hydrogen production using a Zn-air battery. The system ingeniously integrates the sulfur oxidation reaction (SOR) and the hydrogen evolution reaction (HER) into a single, efficient process. Central to this system is the trifunctional phosphorus-doped cobalt molybdate catalyst (P-CoMoO4/NF), which exhibits superior performance in both HER (ηj = 100 = 0.13 V) and SOR (ηj = 100 = 0.30 V) with remarkable stability (∼360 h), reaching 0.64 V at 100 mA cm-2 for simultaneous sulfur ion degradation and hydrogen production. Through density functional theory simulations and extensive characterizations, it has been shown that phosphorus doping in the cobalt molybdate catalyst facilitates electron redistribution, enhancing the catalyst's conductivity, generating more oxygen vacancies, and promoting improved mass and electron transfer. This modification also lowers the energy barrier for adsorbing reaction intermediates, thus increasing the hydrogen production rate and sulfur oxide conversion in this self-powered system. In summary, this research marks a substantial advancement in the development of trifunctional catalysts and proposes an eco-friendly, cost-effective strategy for integrated reaction systems, paving the way for sustainable energy solutions.

Biomass-Based Antibacterial Hybrid Engineering Hydrogel for Efficient Solar Steam Generation

Interfacial solar steam generation is recognized as a promising solution to alleviate the scarcity of freshwater resources owing to its utilization of clean solar energy alongside its high efficiency and minimal heat loss. Nonetheless, the utilization of solar energy for water evaporation encounters challenges, primarily manifested in low evaporation rates and efficiency. Herein, we introduced an approach involving the development of a biomass-based hybrid engineering hydrogel evaporator, denoted as CLC (chitosan and lignosulfonate sodium hybrid hydrogel with a carbon nanotube). The construction of this evaporator involves the straightforward blending of lignosulfonate sodium (LS) and marine polysaccharide biomass chitosan (CS) with carbon nanotubes (CNT) serving as the photothermal materials. The interaction between the sulfonic group of LS and the amino group of CS with water molecules, facilitated by hydrogen bonding and electrostatic interactions, reduces the evaporation enthalpy of water, thereby lowering the energy demand for evaporation. Furthermore, the incorporation of LS reduces the thermal conductivity of the as-prepared hydrogel and promotes photothermal management to mitigate heat loss. The CLC hydrogel demonstrates an evaporation rate of 2.48 kg m-2 h-1 and energy efficiency of 90% under one sun illumination. Moreover, the CLC hydrogel exhibits excellent antibacterial properties (98.4%), ensuring that desalinated water meets drinking standards. This high efficiency and eco-friendly biomass hydrogel with antibiological pollution characteristics and purification abilities holds great potential for widespread application of long-term seawater desalination.

Oxygen vacancies enhanced electrocatalytic water splitting of P-FeMoO4 initiated via phosphorus doping

Transition metal oxides (TMOs) are abundant and cost-effective materials. However, poor conductivity and low intrinsic activity limit their application in electrolyzed water catalysts. Herein, we prepared P-FeMoO4 in situ on nickel foam (P-FMO@NF) by phosphorylation-modified FeMoO4 to optimize its electrocatalytic properties. Interestingly, phosphorus doping is accompanied by the generation of oxygen vacancies and surface phosphates. Oxygen vacancies accelerated Mo dissolution during the oxygen evolution reaction (OER), leading to the rapid reconfiguration of P-FMO@NF to FeOOH and regulating the electronic structure of P-FMO@NF. The formation of phosphates is caused by the substitution of some molybdates with phosphates, which further increases the amount of oxygen vacancies. Hence, the OER overpotential of P-FMO@NF at a current density of 10 mA cm-2 is only 206 mV, and the hydrogen evolution reaction (HER) overpotential is 154 mV. It was assembled into a water splitting cell with a voltage of just 1.59 V at 10 mA cm-2 and shows excellent stability over 50 h. These excellent electrocatalytic properties are mainly attributed to the oxygen vacancies, which improve the interfacial charge transfer properties of the catalysts. This study provides new insights into phosphorus doping and offers a new perspective on the design of electrocatalysts.

Interpretation of the phenolation and structural changes of lignin in a novel ternary deep eutectic solvent

Deep eutectic solvents (DES) are promising green solvents for depolymerization and reconstruction of lignin. Revealing the transformations of lignin during DES treatment is beneficial for high potential lignin applications. In this study, bagasse lignin was treated with a binary DES and three ternary DESs, respectively. The results showed that net hydrogen bonding acidity(α-β) value of DES was positively correlated to the increment of phenolic hydroxyl of lignin, and the ternary DES of choline chloride-formic acid-oxalic acid (ChCl-FA-OA) exhibited the best phenolation performances. The phenolic hydroxyl content of ChCl-FA-OA treated lignin was increased by 50.4 %, reaching 2.41 mmol/g under optimum conditions (120 °C, 4 h, ChCl-FA-OA = 1:2:1). Moreover, it was found that the cleavage of β-O-4' aryl ether bond and ester bond were dominant reactions during the treatment, accompanied by condensation reactions. Additionally, the obtained lignin oil contained various syringyl and guaiacyl derived phenolic compounds. Especially, the content of acetovanillone in lignin oil reached 29.94 %, much higher than in previous studies. Finally, the degradation mechanism of lignin in ChCl-FA-OA system was proposed. The present work provided insights into the relationship between lignin phenolation and DES properties. The novel ChCl-FA-OA system can achieve efficient lignin depolymerization, and convert lignin biomass into value-added chemical products.

Fluorine Induced In Situ Formation of High Valent Nickel Species for Ultra Low Potential Electrooxidation of 5-Hydroxymethylfurfural

The Nickel-based catalysts have a good catalytic effect on the 5-hydroxymethylfurfural electrooxidation reaction (HMFOR), but limited by the conversion potential of Ni2+ /Ni3+ , 1.35 V versus RHE, the HMF electrooxidation potential of nickel-based catalysts is generally greater than 1.35 V versus RHE. Considering fluorine has the highest Pauling electronegativity and similar atomic radius of oxygen, the introduction of fluorine into the lattice of metal oxides might promote the adsorption of intermediate species, thus improving the catalytic performance. F is successfully doped into the lattice structure of NiCo2 O4 spinel oxide by the strategy of hydrothermal reaction and low-temperature fluorination. As is confirmed by in situ electrochemical impedance spectroscopy and Raman spectroscopy, the introduction of F weakens the interaction force of metal-oxygen covalent bonds of the asymmetric MT -O-MO backbone and improves the valence of Ni in tetrahedra structure, which makes it easier to be oxidized to higher valence active Ni3+ under the action of electric field and promotes the adsorption of OH- , while the decrease of Co valence enhances the adsorption of HMF with the catalyst. Combining the above reasons, F-NiCo2 O4 shows superb electrocatalytic performance with a potential of only 1.297 V versus RHE at a current density of 20 mA cm-2 , which is lower than the most catalyst.

A Co-based nitrogen-doped lignin carbon catalyst with high stability and wide operating window for rapid degradation of antibiotics

Co-based catalysts play a crucial role in the activation of peroxymonosulfate (PMS) for degradation contaminants. However, the practical application of such catalysts is hindered by challenges like the self-aggregation of Co nanoparticles and leaching of Co2+. In this study, the Co-based catalyst Co-N/C@CL was synthesized from carboxymethylated lignin obtained by grafting abundant carboxymethyl groups into alkali lignin, in which the presence of these carboxymethyl groups enhanced its water solubility and allowed the formation of stable macromolecular complexes with Co2+. This catalyst exhibited a high specific surface area (521.8 m2·g-1) and a uniform distribution of Co nanoparticles. Consequently, the Co-N/C@CL/PMS system could completely remove 20 ppm tetracycline (TC) in 2 min at a rate of 2.404 min-1. Experimental results and DFT calculations revealed that the synergistic effect of lignin carbon and Co NPs accelerated the cleavage and electron transfer of OO bonds, thus promoting the formation of 1O2, OH and SO4-, with 1O2 emerging as the predominant contributor. Moreover, Co-N/C@CL displayed excellent cycling stability and low Co2+ leaching. This work not only provides a feasible strategy for the preparation of highly active and stable Co-based carbon materials but also offers a promising catalyst for the efficient degradation of TC.

Heteroatom-engineered multicolor lignin carbon dots enabling bimodal fluorescent off-on detection of metal-ions and glutathione

Carbon dots (CDs) have emerged as a promising subclass of optical nanomaterials with versatile functions in multimodal biosensing. Howbeit the rapid, reliable and reproducible fabrication of multicolor CDs from renewable lignin with unique groups (e.g., -OCH3, -OH and -COOH) and alterable moieties (e.g., β-O-4, phenylpropanoid structure) remains challenging due to difficult-to-control molecular behavior. Herein we proposed a scalable acid-reagent strategy to engineer a family of heteroatom-doped multicolor lignin carbon dots (LCDs) that are functioned as the bimodal fluorescent off-on sensing of metal-ions and glutathione (GSH). Benefiting from the modifiable photophysical structure via heteroatom-doping (N, S, W, P and B), the multicolor LCDs (blue, green and yellow) with a controllable size distribution of 2.06-2.22 nm deliver the sensing competences to fluorometric probing the distinctive metal-ion systems (Fe3+, Al3+ and Cu2+) under a broad response interval (0-500 μM) with excellent sensitivity and limit of detection (LOD, 0.45-3.90 μM). Meanwhile, we found that the addition of GSH can efficiently restore the fluorescence of LCDs by forming a stable Fe3+-GSH complex with a LOD of 0.97 μM. This work not only sheds light on evolving lignin macromolecular interactions with tunable luminescent properties, but also provides a facile approach to synthesize multicolor CDs with advanced functionalities.

Electrocatalytic Lignin Valorization into Aromatic Products via Oxidative Cleavage of Cα-Cβ Bonds

Lignin is the most promising candidate for producing aromatic compounds from biomass. However, the challenge lies in the cleavage of C-C bonds between lignin monomers under mild conditions, as these bonds have high dissociation energy. Electrochemical oxidation, which allows for mild cleavage of C-C bonds, is considered an attractive solution. To achieve low-energy consumption in the valorization of lignin, the use of highly efficient electrocatalysts is essential. In this study, a meticulously designed catalyst consisting of cobalt-doped nickel (oxy)hydroxide on molybdenum disulfide heterojunction was developed. The presence of molybdenum in a high valence state promoted the adsorption of tert-butyl hydroperoxide, leading to the formation of critical radical intermediates. In addition, the incorporation of cobalt doping regulated the electronic structure of nickel, resulting in a lower energy barrier. As a result, the heterojunction catalyst demonstrated a selectivity of 85.36% for cleaving the Cα-Cβ bond in lignin model compound, achieving a substrate conversion of 93.69% under ambient conditions. In addition, the electrocatalyst depolymerized 49.82 wt% of soluble fractions from organosolv lignin (OL), resulting in a yield of up to 13 wt% of aromatic monomers. Significantly, the effectiveness of the prepared electrocatalyst was also demonstrated using industrial Kraft lignin (KL). Therefore, this research offers a practical approach for implementing electrocatalytic oxidation in lignin refining.

Lignocellulosic Biomass-Based Carbon Dots: Synthesis Processes, Properties, and Applications

Carbon dots (CDs), a new type of carbon-based fluorescent nanomaterial, have attracted widespread attention because of their numerous excellent properties. Lignocellulosic biomass is the most abundant renewable natural resource and possesses broad potential to manufacture different composite and smart materials. Numerous studies have explored the potential of using the components (such as cellulose, hemicellulose, and lignin) in lignocellulosic biomass to produce CDs. There are few papers systemically aiming in the review of the state-of-the-art works related to lignocellulosic biomass-derived CDs. In this review, the significant advances in synthesis processes, formation mechanisms, structural characteristics, optical properties, and applications of lignocellulosic biomass-based CDs such as cellulose-based CDs, hemicellulose-based CDs and lignin-based CDs in latest research are reviewed. In addition, future research directions on the improvement of the synthesis technology of CDs using lignocellulosic biomass as raw materials to enhance the properties of CDs are proposed. This review will serve as a road map for scientists engaged in research and exploring more applications of CDs in different science fields to achieve the highest material performance goals of CDs.

Sustainable Polyvinyl Chloride-Derived Soft Carbon Anodes for Potassium-Ion Storage: Electrochemical Behaviors and Mechanism

Soft carbon is a promising anode material for potassium-ion batteries due to its favorable properties such as low cost, high conductivity, stable capacity, and low potential platform. Polyvinyl chloride, as a white pollutant, is a soft carbon precursor that can be carbonized at varying temperatures to produce soft carbons with controllable defect and crystal structures. This work investigates the effect of carbonization temperature on the crystalline structures of the obtained soft carbons. In situ Raman spectroscopy was used to elucidate the adsorption-intercalation charge storage mechanism of potassium ions in soft carbons. Soft carbons prepared at the temperature of 800 °C have a defect-rich, short-range ordered structure, which provides optimal intercalation and adsorption sites for potassium ions, resulting in a satisfactory capacity of 302 mAh g-1 . This work presents new possibilities for designing soft carbon materials from recycling plastics for potassium-ion batteries.

Zinc Vacancy Promotes Photo-Reforming Lignin Model to H2 Evolution and Value-Added Chemicals Production

Lignin, rich in β-O-4 bonds and aromatic structure, is a renewable and potential resource for value-added chemicals and promoting H2 evolution. However, direct photo-reforming lignin remains a huge challenge due to its recalcitrant structure. Herein, a collaborative strategy is proposed by dispersing Pt on zinc-vacancy-riched ZnIn2 S4 (Pt/VZn -ZIS) for revealing the effect of lignin structure during photo-reforming process with lignin models. And a series of theoretical calculations and experimental results show that lignin model substances with more nucleophilic group structures will have a stronger tendency to occur the photo-reforming reactions. In addition, benefiting of Pt-S electronic channel is formed by occupying Pt atom onto zinc vacancies in ZnIn2 S4 , which can effectively reduce the energy barrier of H2 evolution and accompany the selective oxidation of lignin model from Cα-OH to Cα = O under simulated sunlight. The natural lignin is used to further demonstrate this selective oxidation mechanism. The presented work demonstrates the photo-reforming lignin model mechanism and the influence of lignin-structure during the process of photo-reforming.

Structure and Interface Engineering of Ultrahigh-Rate 3D Bismuth Anodes for Sodium-Ion Batteries

Sodium-ion batteries (SIBs) have attracted tremendous attention as promising low-cost energy storage devices in future grid-scale energy management applications. Bismuth is a promising anode for SIBs due to its high theoretical capacity (386 mAh g-1 ). Nevertheless, the huge volume variation of Bi anode during (de)sodiation processes can cause the pulverization of Bi particulates and rupture of solid electrolyte interphase (SEI), resulting in quick capacity decay. It is demonstrated that rigid carbon framework and robust SEI are two essentials for stable Bi anodes. A lignin-derived carbonlayer wrapped tightly around the bismuth nanospheres provides a stable conductive pathway, while the delicate selection of linear and cyclic ether-based electrolytes enable robust and stable SEI films. These two merits enable the long-term cycling process of the LC-Bi anode. The LC-Bi composite delivers outstanding sodium-ion storage performance with an ultra-long cycle life of 10 000 cycles at a high current density of 5 A g-1 and an excellent rate capability of 94% capacity retention at an ultrahigh current density of 100 A g-1 . Herein, the underlying origins of performance improvement of Bi anode are elucidated, which provides a rational design strategy for Bi anodes in practical SIBs.

Lignosulfonate-assisted in situ synthesis of Co9S8-Ni3S2 heterojunctions encapsulated by S/N co-doped biochar for efficient water oxidation

The development of highly active and stable earth-rich electrocatalysts remains a major challenge to release the reliance on noble metal catalysts in sustainable (electro)chemical processes. In this work, metal sulfides encapsulated with S/N co-doped carbon were synthesized with a one-step pyrolysis strategy, where S was introduced during the self-assembly process of sodium lignosulfonate. Due to the precise coordination of Ni and Co ions with lignosulfonate, an intense-interacted Co₉S₈-Ni₃S₂ heterojunction was formed inside the carbon shell, causing the redistribution of electrons. An overpotential as low as 200 mV was obtained over Co₉S₈-Ni₃S₂@SNC to reach a current density of 10 mA cm^-2. Only a slight increase of 14.4 mV was observed in a 50 h chronoamperometric stability test. Density functional theory (DFT) calculations showed that Co₉S₈-Ni₃S₂ heterojunctions encapsulated with S/N co-doped carbon can optimize the electronic structure, lower the reaction energy barrier, and improve the OER reaction activity. This work provides a novel strategy for constructing highly efficient and sustainable metal sulfide heterojunction catalysts with the assistance of lignosulfonate biomass.