Markus Antonietti

Kaolin–Cellulose–Lignin Biocomposites Inspired by Termite Mounds for Sustainable Structural Materials

This study presents a bioinspired structural material that mimics the chemical composition and preparation process of termite mounds by fabricating a composite of kaolin, cellulose microfibrils, and lignin without any additional thermal energy. We investigated the roles of each component in the composites: kaolin as the matrix, cellulose as the filler (reinforcement), and lignin as the binder. Our findings revealed that cellulose and lignin contents tuned the mechanical properties and the wettability of the biocomposites, attributed to their dense intertwined structure and hydrophobicity, respectively. At an optimal composition, namely, C49-K/L40 (49 wt % cellulose at kaolin/lignin = 40 w/w), the composite achieves a compressive strength of 148 MPa and a strain at maximum stress of 37%, exhibiting much higher stress than conventional concrete yet significantly higher strain and, consequently, superior toughness. This composite material exceeds the performance of most other biobased alternatives, representing a significant step toward developing sustainable, high-performance materials.

Role of Binders on the Performance of SnO 2 ‐Based Gas Diffusion Electrodes for Electrochemical CO 2 Reduction to Formic Acid

Sustainable Pathways to Flexible and Recyclable Phosphorescent Fibers From Natural Bamboo

Activating Ionic Carbon Nitrides via Epitaxial Dyadic Coupling for Efficient Solar‐Driven H ₂ O ₂ Generation

Incorporation of Organic Counter‐Cations Into Poly(Heptazine Imide) Networks for Promoting Proton‐Coupled Electron Transfer During Photocatalytic H ₂ O ₂ Evolution

Incorporation of Organic Counter‐Cations Into Poly(Heptazine Imide) Networks for Promoting Proton‐Coupled Electron Transfer During Photocatalytic H ₂ O ₂ Evolution

Theory-Guided Discovery of Ion-Exchanged Poly(heptazine imide) Photocatalysts Using First-Principles Many-Body Perturbation Theory

High Resolution Image Download MS PowerPoint Slide Poly(heptazine imides) (PHI) show strong promise in photocatalysis, but limited control over electronic properties continues to constrain their full potential. We modulated PHI’s photocatalytic activity to overcome this limitation by incorporating mono-, di-, and trivalent metal cations into its framework. We employed calculations based on many-body perturbation theory─a highly accurate approach for electronic structure calculations─which provides improved accuracy in quasiparticle energy predictions compared to conventional density functional theory, particularly for band gaps and excitonic properties, to elucidate the underlying mechanisms. The coupling between exchanged metals and the resulting optoelectronic properties is often nontrivial: Pd, Pt, and Cu 1+, for example, produce favorable band structures but show limited photocatalytic activity due to optically forbidden intra-atomic d–d transitions. Our analysis identified several metal-doped PHI systems with electronic structures well suited for hydrogen and oxygen evolution, CO 2 reduction, and H 2 O 2 production. Guided by these theoretical insights, we synthesized a subset of M -PHI materials (where M is either K, Na, Li, Ca, Mg, or Zn) predicted to enhance photocatalytic reactivity. Photocatalytic measurements confirm substantial increases in H 2 O 2 generation rates─up to 4.5-fold higher than undoped PHI─for these candidates, underscoring the effectiveness of our design strategy. These findings offer molecular-level insights into tailoring M -PHI interactions, paving the way for next-generation photocatalysts.

Site Defects and Structural Alignment Enhance Interfacial Charge Mobility in Heterostructured Carbon Nitride Catalysts

High Resolution Image Download MS PowerPoint Slide Engineering interfaces between organic semiconductors is an effective way to tailor organic electronic device performance, as charge transport and light interaction efficiency are strongly influenced by electronic coupling at molecular interfaces. Scanning transmission electron microscopy is routinely used to analyze interfaces at the atomic scale; however, its use for organic materials is limited due to the electron beam sensitivity of organic molecules, buried interfaces, and the semicrystalline nature of organics. In this work, we developed a workflow to correlate charge behavior at organic interfaces with their chemistry and structure, even when interface components are chemically and structurally similar and mixed at the nanoscale. We used this workflow to reveal the nanoscale mechanism behind enhanced charge transfer at the heterojunction between two-dimensional carbon nitride catalysts (poly-heptazine imide (PHI) and poly-triazine imide (PTI)) during the oxygen reduction reaction. We found that PHI crystallites grow on PTI layers formed at the gas–liquid interface in the salt melt, following the [001] PTI /[001] K-PHI orientation. This crystallographic alignment promotes the charge transfer from PTI to PHI and creates an electron-rich interface. Electron energy loss spectroscopy showed quaternary N atoms in the heterojunction, which aid O 2 adsorption and 2e – reduction to H 2 O 2, as well as a higher proportion of terminal and bridging N atoms, promoting charge separation during the reaction.

Thermal condensation drives molecular evolution of biochar-derived dissolved organic matter for heavy metal immobilization

Biochar-derived dissolved organic matter (BDOM), the soluble fraction of biochar, plays an important yet underrecognized role in environmental chemistry, here exemplified by heavy metal mobilization/immobilization. Current studies largely emphasize biochar as a beneficial additive to soil, but neglect the specific role of the highly functional BDOM. In an integrated approach combining spectroscopic analysis, ultrahigh-resolution mass spectrometry, and reaction network modeling, we show that BDOM is the overlooked reactive fraction in biochar application. The complex condensation-derived molecular structures of BDOM across a range of typical pyrolysis temperatures (300-700°C) was analyzed, and molecular transformations changed by metal coordination were elucidated. We demonstrate that higher pyrolysis temperatures facilitate decomposition of humic aggregates and form tyrosine-like phenolic ligands. Using cadmium (Cd) binding as a model metal-interaction process, we show that low temperature pyrolysis produces soluble condensation products which mobilize Cd, while Cd mobility is strongly reduced by the high temperature pendants. This transformation occurs via coordinative mechanisms involving rearrangement of functional groups, conformational changes in polymer structures, and hydrophobic microencapsulation. Finally, we demonstrate that the optimized coordination structure significantly suppresses Cd mobility in the environment and especially minimizes plant uptake. Our thermally controlled synthesis sheds a new light on the role of BDOM and provides a rationale for the controversial reports on different biochars in soil applications.

Polyethylene Terephthalate Monomerization via Glycolysis and Methanolysis Using Metal‐Free Basic Carbocatalyst

The giant amount of disposed Polyethylene Terephthalate (PET) has become a big environmental challenge. Waste PET is herein catalytically depolymerized and monomerized via glycolysis (using ethylene glycol as a solvent) as well as by methanolysis (using Methanol as a solvent). For this purpose, a novel, sustainable, metal‐free basic carbocatalyst in pellet form was synthesized. Employing this catalyst in pure PET glycolysis led to a yield of bis(hydroxyethyl) terephthalate (BHET) of 76.3 mol% under optimal conditions (468 K, 1 h reaction time). Using flakes of a real PET bottle waste, a 58.9 mol% was achieved but required 3 h, attributed to altered partial crystallinity (proved by XRD). In other hand, the use of the same basic carbocatalyst in methanolysis produces a dimethyl terephthalate (DMT), with a maximum yield of 98.9 mol% at 468 K. Whereas 89.7 mol% was obtained using flakes of a real PET bottle waste in 2 h. These results highlight the potential for using the metal‐free basic carbocatalyst for efficient PET recycling processes.

Laser-carbonized anodes for sodium-ion batteries: A sustainable fabrication route toward spatially resolved and practical energy storage

Laser-induced carbonization of polymer films offers a rapid, scalable, and additive-free route to functional carbon materials. Here, a hierarchically structured hard carbon anode is developed by laser carbonizing 5-hydroxymethylfurfural (HMF)-based films under ambient conditions. Optimizing laser power yields a vertically graded architecture with a graphitic-like surface and a disordered, microporous core. The resulting binder- and additive-free anode exhibits high electronic conductivity, ion-accessible porosity, and mechanical stability. Despite high areal mass loading (>4 mg cm⁻²), the anode delivers high reversible capacity, excellent rate capability, and >85 % capacity retention over 300 cycles. Operando Raman spectroscopy reveals phase-specific sodium storage mechanisms: surface-confined interactions in graphitic regions and highly reversible pore-filling in disordered domains. These insights clarify the roles of local structure and porosity in charge storage. This work demonstrates laser carbonization as a powerful platform for producing performance-tuned carbon electrodes for practical sodium-ion battery applications.

Nitrite Reduction at Low Overpotentials on N-Doped Carbon: When Metal Single Atoms Become Poisons

High Resolution Image Download MS PowerPoint Slide We report a nitrogen-doped carbon derived from tetracyanoquinodimethane (TCNQ900) that alone catalyzes nitrite reduction (NO 2 – RR) to NH 3 with an onset potential higher than +0.10 V vs RHE and catalytic activity rivaling state-of-the-art transition-metal catalysts. Contrary to the usual view that carbon supports merely modulate metal sites, we show the reverse: atomically dispersed Cu on TCNQ900 poisons active N-rich motifs, preventing the formation of a tandem catalyst in which NO 3 – is first reduced to NO 2 – by Cu and subsequently to NH 3 by TCNQ900. Molecular analogues confirm that Cu coordination blocks N-rich pockets that drive the NO 2 – RR. In contrast, physically mixing Cu nanoparticles with TCNQ900 restores a true tandem effect: Cu NPs reduce NO 3 – to NO 2 –, while unpoisoned TCNQ900 converts NO 2 – to NH 3, achieving 4-fold higher partial currents. These findings overturn the “noninnocent” support concept and highlight the reciprocal influence of metals on carbon catalysts, providing new designing guidelines and pointing to the potential role of carbon supports as active actors in catalysis.

Impact of Artificial Humic Acid on the Migration and Transformation of Soil Phosphorus

Boron-Induced Electronic Modulation and Nanocrystal Fragmentation Synergistically Boost Photocatalytic Water Oxidation in Ionic Carbon Nitrides

High Resolution Image Download MS PowerPoint Slide Photocatalytic water oxidation is a critical half-reaction to realize overall water splitting, yet it remains challenging due to sluggish reaction kinetics and the need for efficient active centers. To overcome these limitations, we introduce a dual strategy combining boron doping with nanocrystal fragmentation to boost the photocatalytic oxygen evolution reaction (OER) performance of ionic carbon nitrides. The optimal catalyst ( 0.25%B -KPHI) achieves an apparent quantum efficiency of 4.6% at 420 nm with CoO x as a cocatalyst for OER, outperforming most previously reported carbon nitride photocatalysts. Extensive experimental analyses revealed that boron incorporation induces the fragmentation of nanocrystalline domains within the potassium poly(heptazine imide) (KPHI) matrix, resulting in extended visible-light absorption, improved hydrophilicity, more efficient charge separation, and accelerated water oxidation kinetics. Comprehensive density functional theory calculations further showed that boron preferentially localizes at the edges of heptazine units near structural defects, where it serves as a potential adsorption site for water and substantially lowers the energy barrier for the formation of the *O intermediate.

Water Electrolysis Beyond Platinum: Carbon Nitride Materials for Electrochemical Hydrogen Evolution

Tunability of Carbon Nitrides for Enhanced Photocatalytic Oxygen Evolution Reaction

This study presents a systematic theoretical and experimental investigation aimed at optimizing the photocatalytic oxygen evolution reaction (OER) performance of poly(heptazine imides) containing metal cations (PHI-Ms). Deploying advanced density functional theory (DFT) and time-dependent DFT calculations, time-resolved spectroscopy, and photocatalytic OER measurements, we established key design principles for enhancing the OER activity: (i) favoring Co and Fe cations in the +III oxidation state to improve light-harvesting and reduce the Gibbs free changes; (ii) minimizing the content of K+ co-cations, which negatively affect catalytic performance by increasing the desorption Gibbs free energy of O2 and promoting charge localization; (iii) avoiding high concentrations of metal cation to limit agglomeration and mitigate charge recombination; and (iv) exploring oxygen doping of the PHI layer by substituting N atoms located away from the metal active sites, thereby enhancing charge separation and promoting hole generation. These insights offer valuable design guidelines for the development of PHI-M systems with improved photocatalytic performance, advancing the potential of earth-abundant catalysts for practical water-splitting applications.

Synergistic Effect on the Photocatalytic CO₂ Hydrogenation to Methanol Using Dual Co–Cu Single Atom Poly(heptazine imide): Influence of Pressure on Product Selectivity

High Resolution Image Download MS PowerPoint Slide Single metal atom-doped materials are gaining importance in photocatalysis since they offer potential maximum atom economy in a system. Herein, the preparation of poly(heptazine imide) (PHI) carbon nitride materials having Cu 2+ or Co 2+ single atom sites or dual Cu 2+ and Co 2+ sites is reported. The materials have been characterized by chemical analysis, X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS), while the single-atom nature of the metal dopants is supported by high-resolution high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) and X-ray absorption spectroscopy (XAS). The latter also shows a pronounced Cu 2+ –Co 2+ coordination. The resulting three metal-PHI samples were then explored as photocatalysts for the photocatalytic activation of CO 2 reduction at various pressures from ambient to 35 bar. A drastic change in the products from CO and CH 4 under ambient pressure to formic acid and methanol at high pressure was observed, with formic acid being the predominant product at intermediate pressures. The products derived from CO 2 were firmly confirmed by 13 C isotopic labeling monitored by gas chromatography-mass spectrometry (GC-MS) (gas products) or 1 H NMR spectroscopy (liquid products). A synergy between Cu 2+ and Co 2+ was observed in the photocatalytic experiments, the activity following the order Co–Cu/PHI > Cu/PHI > Co/PHI and interpreted as derived from the complementary action of each cation, Cu promoting H 2 activation better than Co and Co promoting hydrogenation of adsorbed CO at lower energy than Cu. These findings show the potential of synergistic effects among different single atoms on a semiconducting support to enhance photocatalytic activity. In addition, the data through light on the importance of pressure to control the product distribution in the photocatalytic CO 2 hydrogenation toward the more valuable liquid products.

Hemicellulose from mild extraction of biomass: Revealing structural insights and advancing potential value

• A mild extraction approach allows controlled tuning of hemicellulose structure. • The relationship between the structure of hemicellulose and its chemical properties was discussed. • Soft-extracted hemicellulose exhibits self-assembly and formulation potential without. • Adjustable extraction offers a sustainable path for sustainable hemicellulose applications. Hemicellulose is one of the main components of biomass, though often overlooked in technical applications. Its valorization depends on the properties of this natural carbohydrate polymer, which are defined by the type of biomass, and structural changes occurring during extraction processes. In this study, hemicellulose was extracted from various plant species using mild alkaline treatment, allowing to obtain polymers with close to their natural structure while differ from traditional descriptions of common commercially available xylans. Namely, lignin bonded to the carbohydrate and native degree of acetylation allows for amphiphilic properties of hemicelluloses. The surface activity and self-organization behaviour upon drying are though influenced mostly by the polymer molecular weight and branching. Hemicelluloses exhibit perforated lamellae structure at 10 minutes extraction times, whereas extraction exceeding 100 minutes results in hemicelluloses with lower surface activity. As extraction time increased, the molecular weight of hemicellulose decreased from 10⁴ to 10³ g/mol, accompanied by a reduction in the polydispersity index and a shift of the diffraction maximum to lower angles by 1.0° to 1.4°, indicating an increase in packing density. The consistency was supported by multidimensional characterization, demonstrating that isolating hemicellulose through mild extraction can modify its properties for applications in surfactants and adhesives.

Histidine‐Based “Transfer Stations” at Carbon‐Immobilized Metal Particles Enable Rapid Hydrogen Transfer for Efficient Formic Acid Dehydrogenation

The interaction of surface metal species with the solution plays a key role in engineering heterogeneous catalytic processes. Herein, we present the facile synthesis of L‐histidine‐coordinated PdAg nanoparticles (4.03 ± 0.08 nm) anchored on pristine carbon supports (denoted as PdAg‐NH 2 /C) and their use for formic acid dehydrogenation (FAD). Significant acceleration of FAD related to the histidine is observed, and the enhancement mechanism is experimentally and theoretically investigated. The presence of L‐histidine at metal sites promotes rapid binding of formic acid molecules due to acid–base interactions. The local enrichment of both protons and formate at the metal‐solution interfaces promotes the subsequent formate decomposition and hydride transfer to the metal surface. The as‐generated surface H species are more concentrated compared to the previously reported catalyst where the metal is loaded on an amino modified support, this enabling a significantly enhanced H 2 production. The optimal Pd 1 Ag 1 ‐NH 2 /C catalyst exhibits a high turnover frequency (TOF) of 6493.5 h −1 at 333 K based on the total amount of Pd, together with an H 2 selectivity of 100%. This study emphasizes the critical role of optimizing local transport pathways near catalytic centers chemically and further provides insights into the rational development of heterogeneous catalysts for FAD technologies.

Promoted Photosynthesis in Seawater by Carbon Nitride and Related Systems

High Resolution Image Download MS PowerPoint Slide The direct utilization of abundant solar energy and seawater positions artificial photosynthesis as a potential technology with unmatched sustainability. While the dissolved ions in seawater are generally regarded to drive corrosion and deactivation of catalysts, they actually were found to have a strong positive effect on carbon nitride photocatalysts for various light-driven reactions. The interaction between the catalysts and seawater ions, referred to as the “Ion Effect”, facilitates light harvesting, charge separation and transfer, and surface redox reactions of carbon nitride photocatalysts. This perspective examines a selection of case studies that showcase seawater-promoted photosynthesis using carbon nitride photocatalysts. It focuses on the mechanistic aspects of the Ion Effect and its prominent advantages for heterogeneous photocatalytic processes. The perspective aims to encourage further advancements in this emerging and practically relevant area.