Abstract: Formaldehyde (HCHO) is a critical indoor pollutant that necessitates efficient removal strategies. Achieving efficient adsorption/catalytic and recycling of metal oxides for HCHO removal is challenging due to the limited exposure of active sites. In this study, a series of TiO2 composites modified with graphene and cerium oxide were synthesized via a sol–gel method to address HCHO removal. Experimental results revealed that the composite labeled 1 %G-Ce0.2-TiO2 achieved the highest adsorption/catalytic performance, with a maximum adsorption capacity of 11.98 mg/g. The co-modification with CeO2 and graphene enhanced the formation of oxygen vacancies, increased the number of oxygen-containing functional groups, and expanded the specific surface area of the adsorbents. These modifications significantly exposed more adsorption/catalytic sites, thereby boosting the efficiency of HCHO removal. Furthermore, 1 %G-Ce0.2-TiO2 demonstrated robust regeneration capabilities. After a simple heat treatment, the adsorption/catalytic capacity of the regenerated material retained 80 % of the original material's capacity. The strong correlation of the adsorption data with the kinetic and isotherm models confirms the physicochemical synergy between HCHO and 1 %G-Ce0.2-TiO2. The adsorbed HCHO is converted by reactive oxygen species into dioxymethylene (DOM), which is subsequently transformed by additional reactive oxygen species and hydroxyl groups into formate species, and ultimately into CO2 and H2O.

Abstract: Abstract The oriented assembly of heterostructures at the boundaries of nanosheets offers substantial advantages over surface‐based heterostructures, owing to their enhanced built‐in electric fields, more efficient charge transport pathways, and greater accessibility of active sites. However, the precise design of boundary‐engineered heterojunctions remains challenging due to the complex process and unclear growth mechanism. Herein, the development of a boundary‐engineered heterojunction is reported by loading Ce‐Ni(OH) 2 onto the edges of Co‐MOF nanosheets through a regulated electrodeposition process, driven by boundary effect induced by Ce single‐atom doping. A systematic investigation is conducted to explore the effects of boundary effect on the construction of boundary‐engineered heterojunctions. The Co‐MOF/Ce‐Ni(OH) 2 @CC exhibits superior oxygen evolution reaction (OER) activity, achieving an ultra‐low overpotential of 140 mV at 10 mA cm −2 in 1 M KOH. Enhanced by density functional theory (DFT) calculations and in situ Raman characterization, the Ce single‐atom acts as an electron reservoir for Ni sites via the Ce─O─Ni chain during OER, thereby facilitating electron transfer from Ni(OH) 2 to Co‐MOF. This promotes the formation of NiOOH and boosts the OER activity. Furthermore, the Kelvin probe force microscopy (KPFM) analysis reveals that the incorporation of Ce intensifies the local electric field at the nanosheet boundary, and facilitates the deposition of Ni(OH) 2 on the edges, thereby promoting the formation of boundary‐engineered heterojunctions.

Abstract: Highly selective detection of toxic hydrogen sulfide (H2S) is crucial, as it is a by-product of many industrial processes. Metal oxide semiconductors (MOSs)-based chemiresistive gas sensors have been extensively utilized in gas detection; nevertheless, developing MOSs with innovative nanostructures is essential to boost their gas-sensing capabilities. Herein, we prepared porous dodecahedral cobalt tetraoxide (Co3O4) with varying cerium (Ce) doping concentrations using metal-organic framework (MOF) templates for H2S sensing. The sensor based on 3 at.% Ce-doped Co3O4 demonstrated optimum H2S-sensing performance, characterized by high sensitivity (response = |Rg- Ra| / Ra × 100 % = 151.6 %), a short response time (41 s), and excellent selectivity toward 100 ppm H2S at 220 °C. These enhancements are attributed to a large specific surface area, high Co3+/Co2+ ratio, rich surface adsorbed oxygen, and strong H2S adsorption. Density functional theory (DFT) calculations confirmed that Ce-doped Co3O4 exhibited a higher H2S adsorption energy and a greater charge transfer capacity compared to pristine Co3O4. By combining this optimal sensor with the bald eagle search (BES)-optimized random forest (RF) (BES-RF) algorithm, a high prediction accuracy for H2S concentration was achieved. This study provides a new strategy to improve the practicality of MOSs-based gas sensors for indoor toxic gas detection through machine learning assistance.

Abstract: In this work, a new fluorescent organic material, OSA, has been designed and developed for the selective detection of cerium (Ce 3+ ) ions.

Abstract: Deep-sea mud is rich in rare-earth elements, primarily found in fluorapatite, a mineral deposit that forms over hundreds of thousands to millions of years through the accumulation of fish remains. After fish die, biogenic apatite captures rare earth elements from seawater on the seafloor and from pore waters during the diagenesis process. The conventional model for rare earth element enrichment suggests that they are incorporated into the bioapatite crystal structure through solid-state diffusion. However, our data reveal that cerium atoms are instead precipitated within an amorphous layer surrounding bioapatite nanocrystals, as shown by high-energy-resolution X-ray absorption spectroscopy and transmission electron microscopy. Computational simulations further support this finding, predicting that cerium atoms cluster on the surface of fluorapatite. These results suggest that the fluorapatite-water interface plays a crucial role in the enrichment of cerium, as well as other rare earth elements, in marine sediments.

Abstract: This work aims to produce semiconductor nanoparticles capable of harnessing visible light for the degradation of dyes and microbes. Employing an ionic liquid-assisted sol–gel process with varying dopant weight percentages, the study focuses on crafting Cerium (Ce) and Phosphorus (P) doped TiO2 Nanomaterials. Structural assessments, including Powder X-ray Diffraction (confirming the anatase phase), Transmission Electron Microscopy (revealing a particle size of 6.2 nm), Brunauer–Emmett–Teller surface area analysis (yielding 166 m2/gr), and Scanning Electron Microscopy (examining the morphology), were conducted. The catalysts were further evaluated for optical characteristics: UV–vis diffuse reflectance spectrum (indicating an energy gap of 2.59 eV), Electrochemical Impedance Spectroscopy (with an Efb of −0.30 V), and Valence band XPS (showing Evb at 2.03 eV). Substitutional doping of dopants into the TiO2 lattice was confirmed through X-ray photoelectron spectroscopy and Fourier Transform Infra-Red analysis. Photoluminescence Spectrum and Time Correlated Single Photon Counting analysis was employed to investigate electron–hole recombination. These characterizations suggest the catalysts are effective in degrading microorganisms and dyes under visible light exposure. Optimal conditions were obtained using CPT5IL2 at pH 3, 0.10 g catalyst dosage, and an initial dye concentration of 10 mg/L, which were determined to achieve complete dye degradation within 60 min. Furthermore, the catalyst's antibacterial and antifungal activity against Enterobacter aerogenes (MTCC-241, Gram-negative), Salmonella typhimurium (MTCC-98, Gram-negative), and Candida albicans (MTCC-277) were studied.

Abstract: Cerium-based adsorbents are effective for the removal of phosphate from water, with the reactivity of cerium dioxide (CeO2) being highly dependent on the exposed crystal facets. However, molecular-level interactions that control the facet-dependent reactivity toward phosphate adsorption remain elusive. In this study, we synthesized CeO2 nanostructures with distinct morphologies─rods (CeO2-R), octahedrons (CeO2-O), and cubes (CeO2-C)─that predominantly expose the (110), (111), and (100) crystal facets, respectively. Phosphate adsorption on various CeO2 facets was systematically investigated through a series of batch adsorption experiments, complemented by Fourier transform infrared (FTIR) spectroscopy and density functional theory (DFT) calculations. The phosphate adsorption follows second-order kinetics and aligns with the Langmuir isotherm model. This process is facilitated by the formation of inner-sphere complexes between the Ce–OH groups on the CeO2 surface and the phosphate ions. The adsorption performance is significantly influenced by the geometric configuration of the exposed CeO2 facets, with the normalized phosphate adsorption capacity to surface area following the trend of CeO2-R > CeO2-C > CeO2-O. These results may have strong implications for prediction of the fate of contaminants at the solid–liquid interface and optimization of advanced adsorbent materials for water treatment applications.

Abstract: Sulfadimethoxine (SDM) is an antibiotic used in treating bacterial infections, but it poses health risks if it enters human body through food chains. In this study, a grain-boundary-rich high-entropy selenide (CdCoCuMnZn)xSe was prepared by a one-pot solvothermal strategy. Its microstructure, photoactivity and photostability were investigated using various techniques, whose dynamic mechanism was elucidated and the role of elemental doping in enhancing photoelectrochemical (PEC) performance was rigorously evaluated in control groups. For the first time, this high-entropy selenide was applied to construct a PEC aptasensor for highly sensitive and selective SDM detection. A signal amplification strategy was implemented using ferrocene-functionalized hollow cerium-doped CoMn2O4 nanocubes (Ce-CoMn2O4-Fc). The PEC biosensor exhibited a broad linear range from 0.01 to 1000 ng mL-1 and a low detection limit of 1.2 pg mL-1. The sensor was successfully used to detect SDM in milk and water samples, yielding reliable results. This work provides constructive insights into PEC sensor development using the high-entropy material and Ce-CoMn2O4-Fc for enhanced performance. It demonstrates significant potential applications in environmental risk assessment and food safety monitoring using multicomponent materials.

Abstract: In this work, we present a cerium-substituted NiFe-layered double hydroxide (NiFe-Ce LDH) that synergistically activates both the adsorbate evolution mechanism (AEM) and a localized lattice-oxygen mechanism (LOM) for efficient alkaline water oxidation. Atomic Ce incorporation induces charge redistribution through Ce 4f–O 2p interactions, stabilizing Fe sites and upshifting the O2p band to enable controlled lattice-oxygen redox without structural collapse. In situ ATR-SEIRAS and DEMS measurements confirm the simultaneous formation of *OOH and OO* intermediates, indicating the hybrid pathway. The optimized NiFe-Ce LDH achieves an overpotential of 220 mV at 10 mA cm–2 and sustains 500 mA cm–2 operation for 650 h. In a membrane-electrode assembly electrolyzer, it delivers 20 A for over 800 h with only a 0.1 V increase after 850 h. Under simulated wind-power voltage fluctuations (1.45–2.25 V), the catalyst maintains stable performance and demonstrates potential for sustainable hydrogen production in dynamic energy environments.

Abstract: Cerium dioxide nanoparticles (CeO2-NPs) are increasingly used in various industrial applications, leading to their inevitable release into the environment including the soil ecosystem. In soil, CeO2-NPs are taken up by plants, translocated, and accumulated in plant tissues. Within plant tissues, CeO2-NPs have been shown to interfere with critical metabolic pathways, which may affect plant health and productivity. Moreover, their presence in soil can influence soil physico-chemical and biological properties, including microbial communities within the rhizosphere, where they can alter microbial physiology, diversity, and enzymatic activities. These interactions raise concerns about the potential disruption of plant-microbe symbiosis essential for plant nutrition and soil health. Despite these challenges, CeO2-NPs hold potential as tools for enhancing crop productivity and resilience to stress, such as drought or heavy metal contamination. However, understanding the balance between their beneficial and harmful effects is crucial for their safe application in agriculture. To date, the overall impact of CeO2-NPs on soil -plant system and the underlying mechanism remains unclear. Therefore, this review analyses the recent research findings to provide a comprehensive understanding of the fate of CeO2-NPs in soil-plant systems and the implications for soil health, plant growth, and agricultural productivity. As the current research is limited by inconsistent findings, often due to variations in experimental conditions, it is essential to study CeO2-NPs under more ecologically relevant settings. This review further emphasizes the need for future research to assess the long-term environmental impacts of CeO2-NPs in soil-plant systems and to develop guidelines for their responsible use in sustainable agriculture.

Abstract: Photocatalytic C–H activation is an emerging area of research. While cerium chloride photocatalysts have been extensively studied, the role of alcohol additives in these systems remains a subject of ongoing discussion. It was demonstrated that the photocatalyst [NEt4]2[CeIVCl6] (1) produces •Cl and added alcohols exhibit zero-order kinetics. Prior studies by other researchers suggested that 1 and alcohols lead to cerium alkoxide [Ce–OR] and alkoxy radical intermediates. To understand these seemingly divergent mechanistic proposals, an expanded investigation comparing cerium(IV) catalyst 1 and cerium(III) complex [NEt4]3[CeIIICl6] (2), which exhibit markedly different reactivity and C–H selectivity, is disclosed. Our findings reveal that alcohol additives accelerate the conversion of cerium(III) to cerium(IV) catalysts, forming key intermediates such as [NEt4]2[CeIIICl5(HOCH3)] (5) and [NEt4]2[CeIVCl5(OCH3)] (6), driven by excited-state di-tert-butyl azodicarboxylate under blue light irradiation. The active complex 6 releases the •OCH3 radical, in sharp contrast to •Cl radicals initiated by cerium(IV) photoredox catalyst 1. These different reactivity and selectivity profiles can be understood in the context of complex 5 generation and in situ formation of base to afford complex 6. Experimental validation shows enhanced selectivity toward C–H bonds with different reactivity with catalyst 1 and methanol upon the addition of base and decreased selectivity with catalyst 2 and methanol upon the addition of acid. These findings unify the previously contrasting observations of cerium halide/alkoxide photocatalytic systems and provide a comprehensive understanding on the essential role of base/acid and alcohol in selectivity and reactivity.