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Modification of TiO₂ with rare-earth elements is an effective approach to improve photocatalytic efficiency and extend photoactivity into the visible region. Dual-phase anatase-brookite TiO₂ mono-doped with Sm, Gd, Tb, Tm, or Yb, and co-doped with SmGd, SmTb, SmTm, or SmYb, were prepared by a template-free one-step hydrothermal method, and the effects of mono- versus co-doping on the morphological, structural, textural, optical, and photocatalytic properties of the materials were systematically compared. X-ray diffraction, Raman, Fourier-transform infrared, and high-resolution transmission electron microscopy confirmed that the dual-phase anatase-brookite structure is preserved after doping. The formation of mesoporous materials with developed porosity was proven by nitrogen physisorption. It was established that mono-doping favours the formation of powders with increased surface area, while co-doping supports the formation of larger pores. Ultraviolet–visible diffuse reflectance spectroscopy and photoluminescence spectroscopy demonstrated enhanced visible-light absorption and suppressed charge recombination for the doped powders, with stronger effect for co-doped materials due to the synergistic contribution of coupled dopants' energy levels. The photocatalytic performance was evaluated in the degradation of a commercial diclofenac drug under UV and visible-light illumination. In the tests, the most active catalyst was TiO₂ co-doped with Sm and Gd, which reached the drug removal rates of 20.4 % and 79.9 % under visible (>450 nm) and ultraviolet light, respectively. These results provide new insight into the structure–property–activity relationships of mono- and co-doped REE anatase-brookite TiO₂ composition and will aid the optimal design and fabrication of photocatalysts for pharmaceutical waste decomposition in aquatic environments.

Lignin, the most abundant renewable aromatic biopolymer, is increasingly recognized as a versatile precursor for functional environmental materials. This Perspective proposes a chemistry-dimension-function-lifetime framework that links the extraction-dependent heterogeneity of technical lignins, chemical modification, and multiscale material architectures (0D-3D) to environmental functions in sorption, photocatalysis, and sensing. Distinct technical lignins derived from different extraction routes exhibit diverse functional groups, interunit linkages, molecular-weight distributions, and condensation degrees, which govern their transformation into materials such as nanoparticles, fibers, membranes, hydrogels, and aerogels with controlled morphologies, thereby regulating kinetics, mass transport, interfacial accessibility, stability, and lifetime. Chemical modification strategies, including carboxylation, amination, and sulfonation, enhance adsorption capacity, selectivity, and regeneration for heavy metals and organic pollutants, highlighting lignin functionalities as key design parameters for environmental remediation. Beyond adsorption, lignin's conjugated aromatic structure enables intrinsic photoactivity, supporting light-driven degradation pathways in catalytic hybrids, thereby coupling adsorption and photoredox reactivity. With emerging AI-guided design, lignin-derived carbon dots and composite materials further extend functionality toward optical and electrical sensing of volatile organic compounds and metal ions. Controlled chemical modification and morphology regulation further enable tunable biodegradation and environmental persistence, integrating sustainability into material design. This research redefines lignin design by integrating extraction-derived structure with assembly into 0D-3D materials, thereby shaping environmental functionalities and lifetime persistence. Future advances in lignin-based environmentally functional materials should focus on engineering multidimensional architectures, scalable processing, multifunctional integration, and enhancing lignin's adsorption efficiency and controlling material lifetime, paving the way for real-world sustainable remediation and environmental monitoring.

Lignin is widely utilised as a carbon precursor in the development of carbon-based photocatalyst systems. However, its intrinsic functionality and renewable origin make it an attractive non-carbonised platform for direct semiconductor growth. Herein, we demonstrate the dual role of hydrolysis lignin as both a support and a reductant in the synthesis of Cu₂O semiconductors. The resulting photoactive composite was comprehensively characterised by SEM, XRD, XPS, and optical spectroscopy to elucidate the roles of lignin in catalyst formation and performance. The photocatalyst achieved over 90% degradation of the herbicide 2,4-dichlorophenoxyacetic acid (2,4-D) within two hours under H₂O₂-assisted, solar-simulated visible-light irradiation, retaining 89% of its initial efficiency after four consecutive cycles. This stability arises from the synergistic interaction between Cu₂O and the lignin-silica matrix: the chelating ability of lignin suppresses metal-ion leaching and captures Cu²⁺ formed during cycling, thereby preventing secondary pollution. The system also demonstrates effective performance in simulated agricultural wastewater matrices, supporting its potential for practical remediation applications.

TiO₂ nanopowders consisting of anatase and brookite, modified with all the rare earth (RE) group metals (except Pm), were successfully synthesized by a simple template-free one-step hydrothermal method using titanium butoxide as a precursor in water solutions. X-ray diffraction method showed that the addition of rare earth elements influenced the anatase-brookite (A-B) phase composition inconsistently: both an increase and a decrease in the brookite content were observed. XRD peak broadening analysis has been carried out by the Scherrer equation, modified Scherrer equation, the Williamson-Hall method, the Size-strain plot and the Halder-Wagner method. A decrease in the crystallite size due to the RE modification was confirmed in the novel RE/A-B materials. Porosity measurements revealed the mesoporous structure and developed surface area of the samples. UV-Vis diffuse reflectance spectra showed a blue shift compared to unmodified A-B, hereby indicating an increase in the band gap of the modified powders due to a phenomenon of quantum confinement or size quantization. The samples demonstrated high photocatalytic performance, particularly in the reaction of H₂ production, where the activity of RE (Gd, Tb, Tm)/A-B is approximately twice higher compared with A-B. This enhancement in photocatalytic activity is attributed to changes in the electronic structure, a reduction in crystallite size, increased porosity, and a larger surface area than A-B. These materials were also tested for the degradation of Rhodamine B in aqueous media, to prove the potential application in remediation processes.

As humanity ventures beyond Earth, developing radiation-stable coatings from non-fossil sources becomes essential. Beta radiation can significantly harm materials, making it essential to seek resilient, biobased alternatives to work in corrosive environments and high temperatures. Herein, a novel lignin-based coating demonstrating exceptional beta-radiation resistance and anticorrosion properties is presented. The coatings are applied to copper substrates and exposed to 500 kGy electron beam irradiation in air to evaluate their structural and functional stability under extreme conditions. Spectroscopic, microscopic, and thermogravimetric analyses confirm the structural integrity of the coatings post-irradiation. Anticorrosion efficiencies after irradiation are maintained at 99.6% (H2SO4) and 99.8% (NaCl) for 61 μm thick films, while thinner 9.5 μm films show 86.4% and 85.7% protection in the respective media, with a ≈4% performance drop post-irradiation. Adhesion strength improves from 0.28 to 0.49 MPa after irradiation, and the water contact angle decreases from 74° to 66°, indicating an increase in hydrophilicity. The superior performance is attributed to the aromatic structure of lignin and its thermally triggered cyclization, which renders it stable against chemical chain scission by oxygen radicals formed in atmospheric conditions under radiation exposure. The performance of thicker films in anticorrosion tests is attributed to a reduced penetration of corrosive agents, due to better morphological integrity. These findings demonstrate the viability of lignin-based coatings as radiation-stable and environmentally sustainable solutions for protecting metal surfaces in harsh environments.

Natural polymer-based hydrogels hold significant potential for sustainable agriculture by enhancing soil hydration and enabling the controlled release of nutrients. This study shows an easy synthetic approach to substitute up to 75% of commonly used polyacrylamide (PAAm) for commercial agro hydrogels by kraft lignin, keeping swelling performance on the same level. A new semisynthetic hydrogel has been synthesized via cross-linking of kraft lignin produced via the LignoBoost process (LB) with PAAm. The ratio of LB and PAAm in the hydrogel composition and cross-linking density were optimized to obtain hydrogels with suitable performance properties. Hydrogel samples were characterized by thermogravimetric analysis, differential scanning calorimetry, and Fourier transform infrared (FTIR) spectroscopy to evaluate the main characteristics and suggest possible reaction mechanisms and by scanning electron microscopy to study features of the hydrogel network. The investigation of functional properties demonstrated that optimized hydrogel samples with 60% lignin in the composition possess water swelling capacity up to 235 g g^–1 and can significantly increase the water retention of the soil when 2.5% hydrogel is added to the substrate. Moreover, obtained lignin-derived hydrogels have the ability to retain and slow-release urea fertilizer. Thus, lignin-derived urea formulations ensure the sustained cumulative release of urea within 8 days under laboratory conditions, while unencapsulated urea possesses a cumulative release of 97% within 1 h. Investigation of biodegradation using a soil burial test showed that weight loss ranges from 9.5% to 14.5% after 40 days for different hydrogel samples. The proposed method of synthesis of lignin-based hydrogels opens new frontiers in advancing sustainable agricultural technologies.

Iron(III)-crosslinked chitosan (Fe-Ch) offers great potential for the sustainable removal of arsenic from contaminated water sources due to its high adsorption capacity and selectivity for As(V) over background competitors such as phosphate (P(V)). However, this material can have low surface area and high activation energy for chemisorption, which can contribute to a low adsorption rate limiting its scalability. This study investigated parameters impacting the adsorption kinetics of Fe-Ch beads and assessed methods to improve their performance. Batch adsorption experiments and molecular dynamics simulations demonstrated that the identity of anions present during synthesis plays a significant role in the final structure and degree of crosslinking of the beads. Acetate in the synthesis was found to lead to a lower degree of crosslinking and higher surface area, enhancing adsorption kinetics. Moreover, glycine in the synthesis was found to lead to the highest adsorption rates, as its interaction with iron increases the hydrophilicity of the beads and may provide a coordination environment that has higher affinity for arsenate than crosslinked chitosan evidenced by density function theory calculations. We also compared the impact of drying techniques on adsorption performance. Freeze-dried beads were found to be rate-limited by chemisorption while air-dried beads were found to be rate-limited by intraparticle diffusion until the beads reached a swollen state. With the approaches evaluated in this study, the pseudo-second-order rate constant of Fe-Ch beads was increased by 24-fold compared to literature studies without altering selectivity, enhancing their suitability for As(V) remediation.