Indoor air purification is crucial for preserving health and well-being in enclosed spaces. This study presents the successful low-temperature oxidation of CO and ethylene, considered as indoor air pollutants, achieved without employing expensive precious metals. A series of binary CuMnOx samples, with a Cu/(Cu+Mn) ratio of 15 wt%, were prepared using various synthesis procedures and thoroughly characterized to understand their physicochemical and their link with catalytic properties. The findings revealed that copper significantly enhanced the performance of all samples when compared to the pure MnOx materials. For all the pollutants investigated, the best-performing catalyst was the Cu-Mn mixed oxide obtained through a redox route, which achieved complete CO oxidation at room temperature and maintained high activity for over 250 h. For ethylene, it demonstrated superior low-temperature catalytic oxidation compared to the other samples, reaching a T10 equal to 85 degrees C. These remarkable performances were attributed to enhanced oxygen mobility, increased reducibility, and the synergy between copper and manganese, which played a pivotal role in VOC oxidation. Notably, long-term stability tests under continuous flow, variation of GHSV, pollutant and oxygen concentrations, and catalytic performance under wet conditions confirmed the excellent durability and versatility of the catalyst, even at extremely low catalyst loadings. Further catalytic testing and spent catalyst analysis revealed that the low-temperature oxidation mechanism involves a Mars-van Krevelen-like reaction pathway with parallel involvement of both reactive surface oxygen species and molecular oxygen, all of which play a crucial role in the reaction process. Finally, this work provides a systematic correlation between catalytic activity (in terms of both T100 and reaction rate) and structural, redox, acid-base, and electronic properties, demonstrating that the decisive factors differ for CO and C2H4 oxidation.

The growing accumulation of fossil-based plastic waste and the underutilization of organic residues from the agri-food sector highlight the need for alternative, low-impact material solutions. Polyhydroxyalkanoates (PHAs) represent a promising family of bio-based and biodegradable polymers; however, their large-scale deployment is still limited by economic and environmental constraints, strongly influenced by feedstock selection and processing requirements. In Mediterranean regions, orange peel waste (OPW) generated in large quantities by the citrus-processing industry may represent a valuable renewable input for the development of PHA-based biocomposites. In this study, a Life Cycle Assessment (LCA) was performed to evaluate a PHA-based composite reinforced with OPW, following established LCA principles and focusing on a residue-based valorization pathway. The analysis includes the collection and pre-treatment of OPW, PHA production from different feedstock matrices, composite manufacturing, and relevant downstream processing stages. The study aims to quantify the environmental implications of integrating OPW into PHA matrices, identify key hotspots, and support evidence-based material design within circular economy strategies. In addition, it assesses the feasibility of producing a PHA-OPW filament suitable for market-ready applications, developed in collaboration with Krill Design (R).

Removing pollutants for indoor air purification is a key point to ensure the health and well-being of people in confined environments. This work aims to provide new insight into the development of promising manganese oxide catalysts. The effects of different crystalline phases (MnO2 and Mn2O3) and the role of redox properties and structural defects were investigated to abate indoor pollutants at mild temperatures. These materials were extensively characterized through complementary techniques and catalytic tests were performed to oxidize 100 ppm of CO, ethylene, or propylene. The most promising catalyst was obtained through solution combustion synthesis, achieving total removal at 118, 222, and 172 degrees C, respectively, with the highest oxidation rate (2.41, 0.88, and 2.47 mu molg(-1)s(-1)) and lowest activation energy (50, 32, and 45 kJmol(-1)) for the three molecules. The synergy between crystalline phases enhanced the catalytic performance and their distribution in the structure was a crucial parameter affecting the number of structural defects.

Gas diffusion electrodes (GDEs) are key components for enabling the deployment of electrochemical CO2 conversion on a large scale. Most studies focused on optimising the GDEs' performance in aqueous electrolytes, while their use with non-conventional electrolytes integrating CO2 capture and co-catalytic conversion abilities is missing in the literature. Herein, the performance of a newly designed Cu2O/SnO2-based GDE was investigated for the first time in a continuous-feed flow cell at a 10.2 cm(2) scale, both in an aqueous KHCO3 medium and in a binary ionic liquid-organic solvent solution. Outstanding catalyst stability and selectivity, i.e. Faradaic efficiency to CO (FECO) from 84 to 90 % in the aqueous electrolyte, was demonstrated at current densities between -20 and -100 mA cm(-2), establishing a benchmark for the CO2 reduction to CO on a Cu-based GDE. In comparison, a FECO of 35 % (CO/H-2 ratio > 3) was reached at -20 mA cm(-2) with 1-Butyl-3-methylimidazolium triflate ([BMIM][TfO]) in acetonitrile (ACN). Still, stability issues and a performance drop were faced during operation in this aprotic media. Molecular dynamics simulations and ex-situ physical-chemical characterisation assessed that the changes in the catalyst/GDE structure and electrolyte properties started with the displacement of Cu surface atoms from their equilibrium position by ACN molecules, which promotes the subsequent dissolution of Cu in the presence of [BMIM][TfO] molecules. Our findings highlight the significant influence of electrolyte composition on catalyst surface transformation and performance during the reaction. This work unveils critical issues for the practical application of IL-based electrolytes as co-catalysts and CO2 capture media for CO2 electrochemical conversion systems and proposes some mitigation strategies.

Carbon dioxide (CO 2 ) hydrogenation to obtain valuable chemicals and fuels via thermocatalysis or electrocatalysis is a promising and sustainable method for CO 2 utilization.

In recent years, Pd/CeO2 materials have proven to be effective catalysts for the total oxidation of methane. In this work, three different synthesis routes were used to prepare high specific surface area supports, consisting of pure CeO2 and 10 at% Pr-doped ceria (Ce90Pr10). Nano-structured spheres were obtained with a microwave-assisted synthesis, dumbbell-like particles were produced through a urea-based hydrothermal method, and ordered mesoporous oxides were prepared by using SBA-15 as hard-template. The six materials were then impregnated with 2 wt% Pd, calcined at 500 degrees C, and comprehensively characterized. All the samples retained their high surface area after impregnation (75-110 m2 g-1), allowing a good dispersion of palladium. No significant structural or morphological differences were observed upon Pr doping, but a higher Pd oxidation state was induced by Pr-doped supports. However, all Pd/CeO2 and Pd/Ce90Pr10 catalysts exhibited similar activity for dry methane oxidation below 500 degrees C, regardless of the synthesis technique and of the Pr presence: they all achieved almost complete CH4 oxidation at 400 degrees C, showing a really remarkable improvement with respect to analogous low surface area supports. A promoting role of Pr was instead noticed in wet conditions, thanks to its ability to counteract water-induced deactivation phenomena. High-surface-area materials consisting of pure and Pr-doped ceria were synthesized with different procedures and employed as supports for Pd-based catalysts. Thanks to their peculiar textural properties and better Pd dispersion, these mixed oxides exhibited remarkably higher activity towards methane oxidation with respect to analogous samples with low surface area. Pr-doping resulted particularly beneficial in wet conditions, reducing water-induced deactivation effects.image

Addressing the urgent need to mitigate increasing levels of CO2 in the atmosphere and combat global warming, the development of earth-abundant catalysts for selective photo-electrochemical CO2 conversion is a central and pressing challenge. Toward this purpose, two synthetic strategies for obtaining a Cu2O-SnO2 catalyst, namely co-precipitation and core-shell methods, were compared. The morphology and band gap energy of the synthesized materials were strongly different. The photoactivity of the core-shell catalyst was improved by 30% compared to the co-precipitation one, while its selectivity was shifted towards C1 products such as CO and formate. The stability of both catalysts was revealed by an easy and fast EIS analysis, indicating how the effective presence of a SnO2 shell could prevent the modification of the crystalline phase of the catalyst during PEC tests. Finally, directing the selectivity depending on the synthesis method used to produce the final Cu2O-SnO2 catalyst could possibly be implemented in syngas and formate transformation processes, such as hydroformylation or the Fischer-Tropsch process.

The present study reports an improved design for Pd/Ce-Pr catalysts. Pd-impregnated nanostructured ceria-praseodymia catalysts with different compositions were comprehensively characterized and tested for dry and wet methane oxidation. The strong PdO-PrOx interaction, detected via XRD, TPR/TPO, Raman and HRTEM analyses, retains Pd mainly in its oxidized form in the materials with high praseodymium content, thus resulting in a lower activity. Conversely, the introduction of a limited amount of Pr in ceria allows to obtain a more active catalyst (2% of Pd supported on a mixed oxide with 10% of Pr) than the typical Pd/CeO2 systems. Hence, the simultaneous presence of Pd in its reduced and oxidized forms results to be a key factor for high activity. Additionally, the higher hydrophobicity of this sample, investigated through NMR and in situ FTIR, markedly reduces the H2O inhibition effect typical of Pd-based materials, paving the way for using this system in real applications.

Copper-ceria mixed oxides are widely considered promising catalysts for oxidation reactions, especially when the participation of lattice oxygen is required. However, the mechanistic understanding of these catalytic systems is still incomplete, due to their considerable complexity. In fact, copper doping of ceria results in the formation of a significant number of different interacting sites in continuous evolution during the catalytic processes. In the present study, pure and Cu-doped ceria samples were deeply investigated through combined spectroscopic techniques, i.e. XPS, EPR, and in situ FTIR and Raman spectroscopy. Through this systematic approach, the copper sites and lattice defects responsible for the enhanced CO oxidation activity of doped ceria were elucidated. Superficial Cu+ species and small Cu0 clusters promote the adsorption of CO at low temperature, while isolated Cu2+ monomers and dimers well-dispersed in the ceria matrix foster lattice oxygen mobility, involving the sub-surface in the redox phenomena. Consequently, the structure of Cu-doped ceria undergoes substantial modifications throughout CO oxidation in the absence of O2, with the formation of oxygen vacancy clusters. Anyway, these changes are reversible, and structural reorganization in the presence of O2 can occur even at room temperature. The excellent performance of Cu-doped ceria eventually stems from the effective cooperation among the different catalytic sites in the mixed oxide.

CO2 conversion into high-value-added products is becoming increasingly attractive to find substitutes for fossil-based ones and tackle the environmental crisis. Herein, a noble, simple, reproducible, and scalable Cu2O-SnO2 photo-electrocatalyst was synthesized and characterized. Coupling cuprous oxide with tin oxide allowed for protecting unstable Cu+1 species from photo-corrosion. Evidence of the SnO2 stabilization role were found via chronoamperometry tests under chopped light and XPS analysis. An optimized catalytic ink was developed to prepare the photocathodes. The CO2 photo-electroreduction tests demonstrated a prevalent production of CO and formate with Faradaic efficiencies of 35.47 % and 19.58 %, respectively, and a good system stability. Sunlight illumination demonstrated to play a major role to hinder H2 evolution and promote >= C1+ products formation.

The reduction of high CO2 concentrations in the atmosphere is an imperative task to reduce the consequences of the greenhouse effect on our planet. Developing active and selective materials for electrochemical CO2 reduction towards value-added products is mandatory to bring this technology to a practical application. This work studied the effect of assisting Cu and Zn oxides co-precipitation with sonochemistry. Different factors were investigated: the ultrasounds (US) amplitude, the effect of US irradiation time during either precipitation or ageing processes, the precursor concentration and calcination temperature. The synthesised catalysts were tested for the electrocatalytic CO2 reduction reaction in a Rotating Disk Electrode (RDE) system. Faradaic efficiencies >14% towards alcohols were obtained using US-assisted synthesised Cu-based catalysts. Instead, with the US-prepared CupperZinc-based catalysts, the selectivity towards H-2 and C-1 products (CO and formate) was improved, and the syngas productivity was increased by >.1.4-fold compared to the non-sonicated one. The alcohols production of the best Cu-catalyst was also confirmed on scalable electrodes. Controlling the synthesis conditions allowed to tune the physicochemical properties of the nanoparticles, including specific surface area, porosity, crystallite size and phases. Mesoporous materials with a mean pores size of around 25 nm were found to induce a better CO2 diffusion and CO retention time in the porous network, improving the *CO intermediate adsorption at active sites, promoting its dimerisation and thus enhancing the selectivity towards C2+ alcohols. The here reported results open the way for new electrocatalysts designs with properly tuned porosity for the selective CO2 conversion to different valuable products.

The development of efficient CO 2 capture and utilization technologies driven by renewable energy sources is mandatory to reduce the impact of climate change. Herein, seven imidazolium-based ionic liquids (ILs) with different anions and cations were tested as catholytes for the CO 2 electrocatalytic reduction to CO over Ag electrode. Relevant activity and stability, but different selectivities for CO 2 reduction or the side H 2 evolution were observed. Density functional theory results show that depending on the IL anions the CO 2 is captured or converted. Acetate anions (being strong Lewis bases) enhance CO 2 capture and H 2 evolution, while fluorinated anions (being weaker Lewis bases) favour the CO 2 electroreduction. Differently from the hydrolytically unstable 1-butyl-3-methylimidazolium tetrafluoroborate, 1-Butyl-3-Methylimidazolium Triflate was the most promising IL, showing the highest Faradaic efficiency to CO (>95%), and up to 8 h of stable operation at high current rates (−20 mA & −60 mA), which opens the way for a prospective process scale-up.

A set of Cu-Mn oxides was prepared through the simple and effective solution combustion synthesis method by varying the relative amount of copper and manganese. The physico-chemical properties of the samples were investigated through complementary techniques such as N2 physisorption at - 196 & DEG;C, XRD, HR-TEM, Raman spectroscopy, temperature programmed analyses (H2-TPR, O2-TPD, and NH3-TPD), and XPS. The prepared catalysts were tested for the total oxidation of volatile organic compounds (ethylene, propylene, and toluene). The best performances, in terms of total VOC oxidation, were achieved with a copper content ranging from 15 at % to 45 at%. The catalytic test outcomes demonstrate the beneficial effect of acidic sites, oxygen mobility, and redox ability. In particular, ethylene oxidation is mainly favored by oxygen vacancies and redox properties, while propylene and toluene oxidation is mostly enhanced by acidic sites. All the catalysts prepared can totally oxidize the examined pollutants examined below 310 & DEG;C. Moreover, the binary oxides exhibit good catalytic stability over a time-on-stream of 7 h and low water vapor inhibition (5 vol% H2O in the gas stream).

The direct hydrogenation of CO2 into dimethyl-ether (DME) has been studied in the presence of ferrierite-based CuZnZr hybrid catalysts. The samples were synthetized with three different techniques and two oxides/zeolite mass ratios. All the samples (calcined and spent) were properly characterized with different physico-chemical techniques for determining the textural and morphological nature of the catalytic surface. The experimental campaign was carried out in a fixed bed reactor at 2.5 MPa and stoichiometric H2/CO2 molar ratio, by varying both the reaction temperature (200–300 °C) and the spatial velocity (6.7–20.0 NL∙gcat−1∙h−1). Activity tests evidenced a superior activity of catalysts at a higher oxides/zeolite weight ratio, with a maximum DME yield as high as 4.5% (58.9 mgDME∙gcat−1∙h−1) exhibited by the sample prepared by gel-oxalate coprecipitation. At lower oxide/zeolite mass ratios, the catalysts prepared by impregnation and coprecipitation exhibited comparable DME productivity, whereas the physically mixed sample showed a high activity in CO2 hydrogenation but a low selectivity toward methanol and DME, ascribed to a minor synergy between the metal-oxide sites and the acid sites of the zeolite. Durability tests highlighted a progressive loss in activity with time on stream, mainly associated to the detrimental modifications under the adopted experimental conditions.

The conversion of common biomasses derived, as d-glucose, into value-added chemicals has received highest attention in the last few years. Among all processes, the catalytic wet air oxidation (CWAO) of derived biomasses using noble metal-based heterogeneous catalytic systems has been investigated. Nevertheless, the redox effect of such catalysts on such bio-compounds has still to be investigated in detail. In the present work, the activity for the conversion of d-glucose into C6 aldaric acid, lactic acid and levulinic acid of some perovskite type oxides (LaBO3; B: Fe, Co, Mn) characterized by noticeable catalytic properties and stability under hydrothermal conditions, have been investigated. The influence of the reaction temperature and the effect of the catalytic properties on the distribution of the liquid products have been studied. In the best conditions, 50.3 mol.% and 69.5 mol.% of lactic and levulinic acid have been obtained by using LaCoO3 and LaMnO3, respectively. Apart from the oxidative effect, the affinity hydrogen allowed the catalytic conversion of some key intermediates, such as pyruvic aldehyde and hydroxymethylfurfural, into the desired products. LaMnO3, which has resulted to be the most oxidizable/reducible catalyst at low temperatures, has shown the best catalytic activity among the studied catalysts, promoting the conversion of hydroxymethylfurfural to levulinic acid and giving overall the highest yield.

In this study, a set of CuCeOx catalysts was prepared via the coprecipitation method using a Multi-Inlet Vortex Reactor: the Cu wt.% content is 5, 10, 20, 30 and 60. Moreover, pure CeO2 and CuO were synthesized for comparison purposes. The physico-chemical properties of this set of samples were investigated by complementary techniques, e.g., XRD, N2 physisorption at −196 °C, Scanning Electron Microscopy, XPS, FT-IR, Raman spectroscopy and H2-TPR. Then, the CuCeOx catalysts were tested for the CO and ethene oxidation reactions. As a whole, all the prepared samples presented good catalytic performances towards the CO oxidation reaction (1000 ppm CO, 10 vol.% O2/N2): the most promising catalyst was the 20%CuCeOx (complete CO conversion at 125 °C), which exhibited a long-term thermal stability. Similarly, the oxidative activity of the catalysts were evaluated using a gaseous mixture containing 500 ppm C2H4, 10 vol.% O2/N2. Accordingly, for the ethene oxidation reaction, the 20%CuCeOx catalyst evidenced the best catalytic properties. The elevated catalytic activity towards CO and ethene oxidation was mainly ascribed to synergistic interactions between CeO2 and CuO phases, as well as to the high amount of surface-chemisorbed oxygen species and structural defects.

The development of efficient catalysts is one of the main challenges in CO2 conversion to valuable chemicals and fuels. Herein, inspired by the knowledge of the thermocatalytic (TC) processes, Cu/ZnO and bare Cu catalysts enriched with Cu+1 were studied to convert CO2 via the electrocatalytic (EC) pathway. Integrating Cu with ZnO (a CO-generation catalyst) is a strategy explored in the EC CO2 reduction to reduce the kinetic barrier and enhance C-C coupling to obtain C2+ chemicals and energy carriers. Herein, ethanol was produced with the Cu/ZnO catalyst, reaching a productivity of about 5.27 mmol·gcat-1·h-1 in a liquid-phase configuration at ambient conditions. In contrast, bare copper preferentially produced C1 products like formate and methanol. During CO2 hydrogenation, a methanol selectivity close to 100% was achieved with the Cu/ZnO catalysts at 200 °C, a value that decreased at higher temperatures (i.e., 23% at 300 °C) because of thermodynamic limitations. The methanol productivity increased to approximately 1.4 mmol·gcat-1·h-1 at 300 °C. Ex situ characterizations after testing confirmed the potential of adding ZnO in Cu-based materials to stabilize the Cu1+/Cu0 interface at the electrocatalyst surface because of Zn and O enrichment by an amorphous zinc oxide matrix; while in the TC process, Cu0 and crystalline ZnO prevailed under CO2 hydrogenation conditions. It is envisioned that the lower *CO binding energy at the Cu0 catalyst surface in the TC process than in the Cu1+ present in the EC one leads to preferential CO and methanol production in the TC system. Instead, our EC results revealed that an optimum local CO production at the ZnO surface in tandem with a high amount of superficial Cu1+ + Cu0 species induces ethanol formation by ensuring an appropriate local amount of *CO intermediates and their further dimerization to generate C2+ products. Optimizing the ZnO loading on Cu is proposed to tune the catalyst surface properties and the formation of more reduced CO2 conversion products.

Catalytic oxidation is the most effective technology to control methane emissions from both mobile and stationary sources. Palladium-based materials are widely viewed as the most active catalysts for the methane abatement reaction, even though the high-temperature PdO/Pd transition is linked to a decrease in catalytic activity. Aimed at minimizing this phenomenon, this work compares the catalytic activity and the thermal stability of different Pd-impregnated cerium-praseodymium mixed oxides prepared via Solution Combustion Synthesis. Although the palladium deposition on pure ceria allows obtaining a highly active system, the introduction of praseodymium enhances the thermal stability of the catalyst in an extended temperature range. X-ray photoelectron spectra show that the presence of praseodymium retains Pd in a more oxidized form, thus stabilizing the high-temperature active phase. This effect, as evident from X-ray diffractograms and Raman analyses, was attributed to a strong interaction of palladium particles with praseodymium, thereby hindering their reduction to the metallic form. Moreover, Pr doping played a significant role during methane oxidation in the presence of 5% H2O, improving both activity and stability compared to Pd on pure ceria. On the whole, Pd/Ce90Pr10 (2 wt% palladium supported on a mixed oxide with a praseodymium content of 10% on a cerium-praseodymium molar basis) was found to be the most promising catalyst amongst the studied materials in both dry and wet conditions, benefitting from the synergistic effect of ceria and praseodymia in improving the Pd activity and stability.

The present study reports an improved design for Pd/Ce-Pr catalysts. Pd-impregnated nanostructured ceria-praseodymia catalysts with different compositions were comprehensively characterized and tested for dry and wet methane oxidation. The strong PdO-PrOx interactions, detected via XRD, TPR/TPO, Raman and HRTEM analyses, retain Pd mainly in its oxidized form in the materials with high praseodymium content, thus resulting in a lower activity. Conversely, the introduction of a limited amount of Pr in ceria allows to obtain a more active catalyst (2% of Pd supported on a mixed oxide with 10% of Pr) than the typical Pd/CeO2 systems. Hence, the simultaneous presence of Pd in its reduced and oxidized forms results to be a key factor for high activity. Additionally, the higher hydrophobicity of this sample, investigated through NMR and in situ FTIR, markedly reduces the H2O inhibition effect typical of Pd-based materials, paving the way for using this system in real applications.

In the present work, novel ceria-based nanocatalysts containing different quantities of La and Nd were prepared via hydrothermal synthesis. The effects of doping on the structural and physico-chemical properties of ceria were examined with several techniques, such as XRD, FESEM, TEM, Raman spectroscopy, XPS, H-2-TPR and O-2/NH3/ CO2-TPD. The catalytic activity of doped ceria towards CO, NO and soot oxidation was evaluated in different conditions; in particular, the role of the catalyst-soot contact and the influence of NOx and water on the soot oxidation performances were investigated. La and Nd ions were well incorporated in ceria structure, but the final morphology was significantly altered. The introduction of trivalent cations was also associated with a higher abundance of defects and oxygen vacancies, but an excessive oxygen deficiency detrimentally affected the material reducibility and catalytic activity for CO and NO oxidation. Conversely, soot oxidation benefited from La and Nd addition. In particular, the Ce-La equimolar oxide exhibited outstanding performances in all the tested conditions, thanks to its optimal morphology and surface acidity. A detailed comparison with equimolar ceriapraseodymia allowed to investigate how acid-base sites and redox properties control the different catalytic mechanisms involved in standard and NOx-assisted soot oxidation.