Metalloporphyrin-containing mesoporous materials, named VTPP@SBA, were prepared via a simple anchoring of vanadyl porphyrin (5,10,15,20-Tetraphenyl-21H,23H-porphine vanadium(IV) oxide) through a SBA-15-type mesoporous material. For comparison, vanadyl porphyrin was also impregnated on SiO (VTPP/SiO). The characterization results of catalysts by XRD, FTIR, DR-UV-vis, and EPR confirm the incorporation of vanadyl porphyrin within the mesoporous SBA-15. These catalysts have also been studied using electrochemical and photoelectrochemical methods. Impedance measurements confirmed that supporting the porphyrin in silica improved the electrical conductivity of samples. In fact, when using mesoporous silica, current densities associated with oxidation/reduction processes appreciably increased, implying an enhancement in charge transfer processes and, therefore, in electrochemical performance. All samples presented n-type semiconductivity and provided an interesting photoelectrocatalytic response upon illumination, especially silica-supported porphyrins. This is the first time that V-porphyrin-derived materials have been tested for photoelectrochemical applications, showing good potential for this use., This work was supported by the Ministry of Education and Science of the Republic of Kazakhstan (project No. ARP08856825-OT-20) and the Ministerio de Ciencia e Innovación of Spain (projects PID21-126235OB-C31 and PID21-126235OB-C33).

In the present article, a relationship between the catalytic performance in the oxidative dehydrogenation of ethane (ODHE) for Nb-doped NiO catalysts and their electrochemical properties has been proposed. To do so, highly stable and selective Nb-doped NiO catalysts for the ODHE to ethylene have been synthesized by optimizing synthesis parameters such as the amount of oxalic acid in the synthesis gel and the calcination temperature. These catalysts have been characterized by means of XRD, HRTEM, Raman and UV–vis diffuse reflectance spectroscopies, TPR and XPS. Moreover, Electrochemical Impedance Spectroscopy (EIS), capacitance measurements (Mott-Schottky analysis) and cyclic voltammetries studies were also carried out. Electrochemical characterization indicates changes in the type of semiconductivity: p-type for samples calcined at 350 °C and the sample prepared in the absence of oxalic acid and calcined at 500 °C, to n-type for samples prepared in the presence of oxalic acid in the synthesis gel and calcined at 500 °C. According to the obtained results, the most selective catalysts present a low Nb-incorporation on the NiO lattice with a large amount of tiny NbO nanoparticles covering NiO crystallites. This work presents, for the first time, a complete electrochemical characterization of Nb-doped NiO catalysts showing a correlation between electrochemical properties and catalytic performance., The authors would like to thank the the Ministerio de Ciencia e Innovación of Spain, MINECO/FEDER (Projects: TED2021-129555B-I00, PID2021-126235OB-C31, PID2021-126235OB-C33, TED2021-130756B-C32 and MFA/2022/016). Y.A. thanks the Ministry of Higher Education and Scientific Research of Algeria for the National Exceptional Program for the fellowships. A.A. acknowledges Severo Ochoa Excellence Program for his fellowship (BES-2017-080329)., Peer reviewed

Hydrothermally prepared Mo-V-Sb mixed oxides doped with alkali metal cations (Li, Na, K, Rb, or Cs) show a significantly improved catalytic behavior in the oxidative dehydrogenation of ethane (ODH) compared to conventional alkali metal-free MoVSbO catalysts. Initial selectivity to ethylene above 95 % was held up to 20 % of ethane conversion for all alkali metal promoted MoVSbO catalysts, as well as lower ethylene overoxidation at higher ethane conversion, with differences depending on the alkali metal employed. Thus, from Li to K, the enhanced catalytic performance follows a bottom-up trend as increasing the size of the cation. An intermediate behavior is observed though for the catalyst doped with Cs cations, with the highest atomic radius. The K-doped MoVSbO catalyst is the least prone to both ethane total oxidation and ethylene overoxidation, which enables up to 90 % selectivity to ethylene at ethane conversion higher than 65 %., This work was supported by the Ministerio de Ciencia e Innovación of Spain (projects PID21-126235OB-C31 and PID21-126235OB-C33). F. Ivars-Barceló also acknowledges the Ministerio de Ciencia e Innovación of Spain by the support from the “Ramón y Cajal” excellence grant (Ref.: RYC2020-029470-I/AEI/10.13039/501100011033)., Peer reviewed

MoVO, MoVTeO and MoVTeNbO mixed oxides, prepared hydrothermally and heat-treated in N at 400, 500 or 600 °C, are active and selective catalysts in the oxidative dehydrogenation (ODH) of ethane, although their catalytic behaviour strongly depends on the composition and the activation temperature of the material. Thus, the selectivity to ethylene over samples heat-treated at 400 or 600 °C, decreases according to the following trend: MoVTeNb-600 > MoV-400 > MoVTe-600 > MoVTe-400 > MoVTeNb-400 >> MoV-600 (with catalysts heat-treated at 500 °C presenting an intermediate performance). This catalytic performance can be explained to a high extent by the presence of the M1 phase in the best catalysts. Interestingly, the temperature of formation and decomposition of the M1 phase strongly depends on the chemical composition of the catalysts, leading to different trends depending on the heat-treatment temperature. Not only the presence of the M1 phase determines the catalytic performance but also the V/V ratio in the surface of catalysts. Additionally, a comprehensive brand-new electrochemical characterization of the catalysts has been carried out for MoV-based samples with M1 phase. Accordingly, the best catalytic behaviour in terms of selectivity to ethylene in the ethane ODH was observed in those materials presenting higher charge-transfer resistances at the interfacial active parts and n-type semiconductivity with few O-vacancies. Besides, lower current densities obtained in cyclic voltammetries (related to low electrochemical activity) has been associated with higher selectivity in the ODH reaction., The funding received from the Ministerio de Ciencia e Innovación of Spain, MINECO/FEDER (Projects: PID2021-126235OB-C31, PID2021-126235OB-C33, TED2021-130756B-C32 and TED2021-129555B-I00), for this study is acknowledged. A.A. acknowledges Severo Ochoa Excellence Program for his fellowship (BES-2017-080329)., Peer reviewed

In the present article we show that, although the reflux method is not common for the synthesis of multicomponent MoVTeNbO catalysts, an optimized reflux synthesis of metallic precursors leads to efficient materials for the oxidative dehydrogenation of ethane and the selective oxidation of propane into acrylic acid, with the results at the same level as those of the best catalysts reported in the literature to date. It has been demonstrated that the reflux temperature is of paramount importance to achieve active and selective catalysts. Thus, the incorporation of vanadium and niobium to a polyoxometalate in the catalyst precursors is favored by refluxing at 110 °C, promoting the formation of the desired orthorhombic M1 phase. Additionally, the incorporation in the synthesis gel of cations such as ammonium or methylammonium provokes a further improvement of the catalytic performance whenever the activation procedure is carefully controlled., The authors gratefully acknowledge the financial support by the Ministerio de Ciencia e Innovación of Spain, MINECO/FEDER (Projects: PID2021-126235OB-C31, PID2021-126235OB-C33, TED2021-130756B-C32 and TED2021-129555B-I00). F. Ivars-Barceló gratefully acknowledges the support from “Ramón y Cajal” excellence program for recruitment (Ref.: RYC2020-029470-I/AEI/10.13039/501100011033).

11 figures, 3 tables., The growing demand of energy and the increase in the greenhouse gases emissions has caused the search for new renewable energy sources, such as biomass, to replace fossil fuels. Thus, there are different compounds, i.e. γ-valerolactone (GVL), which can be obtained from different biomass-derived substrates such as levulinic acid (LA). In the present work, the catalytic hydrogenation of levulinic acid to γ-valerolactone has been studied, using as a hydrogen source that obtained by photoelectrocatalytic water splitting. The use of the photoelectrocatalytic hydrogen has been conducted in two ways: i) one set-up in two steps involving a cell for hydrogen production and a reactor for the LA to GVL transformation or ii) a novel set-up consisting of just one unit in which hydrogen formation and LA hydrogenation take place simultaneously. The photoelectrocatalyst used for the water to hydrogen reaction is a TiO2 nanostructure synthesized by electrochemical anodization, whereas several catalysts based on ruthenium have been studied for the LA hydrogenation. Optimization in the synthesis procedure of ruthenium catalysts supported on gamma-alumina has allowed high yields to GVL at low reaction temperature (30 °C). The most efficient ruthenium catalyst presenting high proportion of surface metallic ruthenium and high dispersion on the support was that synthesized by a simple precipitation method. Finally, the use of the novel one-unit set-up makes possible not only achieving high GVL yields but also the recyclability of the catalyst with just a scarce loss in productivity, conversely to what happens using the traditional hydrogenation with pressurized hydrogen., The authors would like to acknowledge the Generalitat Valenciana for funding through the CIAICO/2021/094, CIGRIS/2022/198, CIGE/2023/43 and CIGE/2022/166 projects. M.E. is grateful for Grant RYC2021-031428-I funded by MCIN/AEI/10.13039/501100011033 and by European Union NextGenerationEU/PRTR. The authors also thank the Ministerio de Ciencia e Innovación-Agencia Estatal de Investigación and European Union NextGenerationEU through the projects PID2021-126235OB-C33 MCIN/AEI/10.13039/501100011033/FEDER Una manera de hacer Europa, UE and TED2021-129555B–I00/AEI/10.13039/501100011033/Unión Europea NextGenerationEU/ PRTR., Peer reviewed

Non-pure primary Vanadyl petroporphyrins extracted from oil, i.e., PVP(Oil), have been impregnated on SBA-15 or on SiO. For comparison, synthetic vanadyl octaethylporphine, VP(S), was also impregnated on the same siliceous materials. The characterization result of unsupported porphyrins and the catalysts, by FTIR and DR-UV–vis, confirm the successful incorporation of the corresponding vanadyl porphyrins. Electrochemical and photoelectrochemical properties of these catalysts have been evaluated through Electrochemical Impedance Spectroscopy (EIS), Mott-Schottky (MS) and voltammetry tests. According to the results, primary vanadyl porphyrin extracted from oil, PVP(Oil), show better photoelectrochemical response, regardless of the support used (either SiO or SBA15), than synthetic ones, VP(S). Additionally, this study reveals that PVP(Oil) can be used as photoelectrocatalysts for methyl red (MR) degradation (a common organic dye), showing almost a complete degradation of (MR) using PVP(Oil)-SBA15 catalyst after 3 h. Interestingly, an increase of more than 25% in the kinetic constant for the photoelectrochemical degradation of MR is shown for the PVP(Oil) in comparison to the VP(S)., The funding received for this study from the Spanish Ministry of Science and Innovation, Projects PID2021–126235OB-C31 and PID2021–126235OB-C33 funded by MCIN/AEI/10.13039/501100011033 and FEDER funds, and from the Ministry of Science and Higher Education of the Republic of Kazakhstan (Project: AP23486934) is acknowledged. This Special Issue is dedicated to honor the 10th International Symposium on Group V (IV and VI) Elements, a gathering of international researchers, industry, young researchers, and students to help shape the vision of the future for these elements.

NiO−CeO and NiO−CeO−ZrO catalysts have been synthesized, electrochemically characterized (Mott-Schottky (MS) measurements and Electrochemical Impedance Spectroscopy), physicochemically characterized (by N adsorption, XRD, Transmission Electron Microscopy and XPS) and tested in the NO assisted ethane oxydehydrogenation. The use of low Zr-loadings (Zr/Ce=0.1 at. ratio) has led to the optimal results in the ethylene production, improving those obtained by the Zr-free NiO−CeO catalyst. However, high Zr-loadings have meant a decrease in the olefin production. The catalytic results obtained have been explained considering the amount of oxygen vacancies, the crystalline phases formed and, especially, the nature of the surface Ni species. Importantly, the use of NO as an oxidizing agent leads to a remarkable improvement in the selectivity to the olefin compared to that obtained employing molecular O. Then, for a given ethane conversion the selectivity to ethylene is ca. 15 points higher using NO than using O. Another additional positive aspect of this NiO−CeO−ZrO catalyst is its high catalytic stability., The authors would like to acknowledge the Ministerio de Ciencia e Innovación-Agencia Estatal de Investigación through the projects PID2021-126235OB-C31, PID2021-126235OB-C32 and PID2021–126235OB-C33 (funded by MCIN/AEI/10.13039/501100011033 and FEDER funds), and TED2021-129555B-I00/AEI/10.13039/501100011033/Unión Europea NextGenerationEU/PRTR. The authors also thank the Generalitat Valenciana for CIAICO/2021/094 and CIGRIS/2022/198.

16 figures, 3 tables., γ-Valerolactone (GVL) is a versatile platform molecule that can be produced from furfural (FF), a compound readily obtained from biomass. The transformation of FF into GVL can be achieved in a one-pot process through a cascade of reactions involving hydrogenation, ring opening, dehydration, and cyclization. Designing an appropriate catalyst capable of promoting all these steps in a single system is therefore essential. In this work, catalysts based on zirconium supported on Y-zeolite, as well as catalysts supported on Y-zeolite coated with a theoretical monolayer of Nb2O5, were synthesized and evaluated for the conversion of FF into GVL. Reactivity tests were conducted under both batch and continuous-flow conditions. The catalysts were characterized using various techniques, including XRD, FTIR, IR-Py, DR-UV–Vis, HR-TEM, XPS, and NH3-TPD, to determine their physicochemical properties. Among the catalysts studied, Zr supported on Nb-modified Y-zeolite exhibited the highest catalytic activity, achieving a GVL yield of 65 % after 3 h at 180 °C in batch mode using 2-propanol as both hydrogen source and solvent. Similarly, under continuous-flow conditions, this bimetallic catalyst delivered the highest GVL yield (approximately 40 %), representing the best performance reported to date for this reaction. Furthermore, the addition of water to the reaction medium enhanced catalytic performance. Notably, the bimetallic catalyst maintained stable activity throughout the tested time-on-stream., The authors would like to acknowledge the Generalitat Valenciana for CIAICO/2024/087 and CIGRIS/2022/198. The authors also thank the Ministerio de Ciencia e Innovación-Agencia Estatal de Investigación and European Union NextGeneration EU through the projects PID2021–126235OB-C33 MCIN/AEI/10.13039/ 501100011033/FEDER Una manera de hacer Europa, UE and TED2021–129555B–I00/AEI/10.13039/501100011033/Unión Europea NextGenerationEU/PRTR., Peer reviewed

Under a Creative Commons Attribution-NonCommercial 4.0 International licence., Table S1. Comparison between the GVL yield (%) achieved in this work in comparison to the results published in literature for the same reaction in batch mode.
GC-FID calibration for continuous flow reactions:
In order to obtain the moles of the various compounds actually present at the end of the reaction, it is necessary to calibrate the instrument. Calibrations were carried out on the individual compounds, obtaining the standards by diluting the stock solution in 25mL flasks and adding 20μl of octane as an internal standard in each.
The theoretical concentrations of the stock solution and the various standards have been reported in Tables S2 and S3. The compounds used for the calibrations were: furfural (FUR), furfuryl alcohol (FAL), α-angelic lactone (AnL), propyl levulinate (PL), furfuryl ethyl ether (FEE) and γ-valerolactone (GVL). It was not possible to calibrate isopropyl levulinate (which is the molecule that is actually formed during the reaction) as it is not a commercial molecule. It was therefore decided to use its isomer (propyl levulinate) assuming that the two response factors are equal. Furfuryl isopropyl ether (FPE) is also a compound absent on the market and its response factor has been assumed to be the same as that of FEE since it was the closest molecule of those commercially available. The chromatogram obtained from the calibration of the species described is shown in Figure S1.
Table S2. List of compounds used and their quantities for the preparation of stock solutions using iPrOH as a solvent
Table S3. Concentrations of the standards prepared for each individual compound from their own stock solutions
Table S4. XPS results for the different O1s spectral region contributions, The authors would like to acknowledge the Generalitat Valenciana for CIAICO/2024/087 and CIGRIS/2022/198. The authors also thank the Ministerio de Ciencia e Innovación-Agencia Estatal de Investigación and European Union NextGeneration EU through the projects PID2021–126235OB-C33 MCIN/AEI/10.13039/ 501100011033/FEDER Una manera de hacer Europa, UE and TED2021–129555B–I00/AEI/10.13039/501100011033/Unión Europea NextGenerationEU/PRTR., Peer reviewed

This study reports the bio-mediated synthesis of tungsten trioxide nanostructures from aqueous extracts of Melia
azedarach (L.) dry leaves. The synthesis was carried out by electrochemical anodization of tungsten foils in the
presence of different volume percentages of leaves extracts. These nanostructures were afterwards
characterized by X-Ray Diffraction (XRD), impedance measurements and linear sweep voltammetry
in the presence of simulated solar light. Finally, these nanoelectrodes were used as
(photo)electrocatalysts in the photoelectrochemical water splitting process to obtain green hydrogen and as
anodes in Li-ion rechargeable batteries.

Description of methods used for collection/generation of data:

- Synthesis of WO3 nanostructures:

The leaves of M. azedarach were randomly sampled from several
mature trees from the surroundings of the Burjassot Campus of the
University of Valencia (Spain). Fresh leaves were rinsed with tap and
distilled water and subsequently air-dried indoors for 1 week, at room
temperature. The extracts were obtained from dried leaves, by mixing
15 g of material with 150 mL of distilled water at 60 ºC. The infusion was
maintained at that temperature for 20 min. After that, the solution, once
cooled, was filtered through filter paper and used to prepare the
different reaction media.
Nanostructures of WO3 were synthesized by subjecting tungsten foils
(1,3 cm2 of exposed area) to an anodization process with a cell potential
of 20 V, for 4 h. A platinum foil served as the cathode within the cell. The
anodization process employed an aqueous electrolyte composed of
1.5 M methanesulfonic acid (MSA) with varying proportions of M.
azedarach leaves extract (from 0% to 10%, in volume), at a temperature
of 50◦C. Anodization was performed under
controlled hydrodynamic conditions, by means of a Rotating Disk
Electrode (RDE) set a constant rotation speed of 750 rpm. Following
anodization, a thermal treatment (annealing) was carried out in a
tubular oven at 600◦C for 4 h in an air atmosphere to obtain crystalline
WO3 nanostructures.


- Morphological and structural characterization:

X-Ray diffraction analyses (XRD) were performed to investigate the
crystallinity of the WO3 samples. A D8AVANCE diffractometer (Bruker)
equipped with a monochromatic Cu Kα1 source was used.


-(Photo)electrochemical characterization: impedance measurements
and photocurrent density vs potential curves:

Electrochemical characterization of the WO3 nanostructures was
conducted through impedance measurements, performing Electrochemical
Impedance Spectroscopy (EIS) and Mott-Schottky (MS) analyses.
All electrochemical tests were carried out using a three-electrode
cell with the nanostructures acting as working electrodes, a silver/silver
chloride (3 M KCl) electrode was the reference electrode and a platinum
tip served as counterelectrode. Measurements were performed with a
PalmSens4 potentiostat and 0.1 M H2SO4 was used as electrolyte. The
sample area exposed to that electrolyte was 0.5 cm2. For EIS, a constant
potential of 1 V was selected with an amplitude of 10 mV, scanning the
frequency from 100 kHz to 10 mHz. For MS analysis, a constant frequency
of 5 kHz was used, while the potential was scanned from 1 V to
0.2 V at a rate of 50 mV/s.
For the photoelectrochemical characterization of the WO3 nanostructures,
the same experimental set-up was used, with the addition of a
solar simulator with AM 1.5 conditions (100 mW/cm2). Linear voltammetries
to obtain photocurrent density – potential curves were
conducted from 0.2 V to 1.05 V, by applying dark-light pulses (16 s in
the dark followed by 4 s with illumination) while the potential was
scanned.

- Evaluation of WO3 nanostructures as Li-ion battery anodes:

WO3 nanostructures were evaluated as anodes (negative electrodes)
for Li-ion batteries. For that purpose, Swagelok-type cells were used,
with WO3 nanostructures acting as working electrodes and a metallic
lithium foil acting as both the counter and the reference electrodes.
Batteries were assembled inside an Ar-filled glove box, using 1 M LiPF6
in ethylene carbonate/dimethyl carbonate/diethyl carbonate 1:1:1 (v/
v/v) as electrolyte (Sigma-Aldrich) and a Whatman glass microfiber
separator. After sealing the cells, they were cycled outside the glove box
at room temperature, using a Biologic BCS-815 cyclic station. Galvanostatic
charge/discharge curves were recorded at different cycling
rates (from C/10–1 C, and returning to C/10) within a potential window
between 1 V and 3.5 V vs Li/Li+.

[EN] N2O-assisted Oxidative Dehydrogenation (ODH) of ethane is an interesting way of simultaneously obtaining a highly valuable raw material (ethylene) and the functionalization of a greenhouse gas (N2O). Unfortunately, over most of the catalytic systems, this reaction presents two main drawbacks: i) high yields to ethylene have hardly been reported; and ii) the catalytic activity highly decreases when replacing molecular oxygen by N2O. In the present article, it will be shown that with promoted NiO catalysts, and using N2O, high activity, comparable with that of conventional O2-assisted ODH of ethane, is achieved. Furthermore, the use of the appropriate dopant, such as niobium, allows high ethylene yields (40 %), with a selectivity to ethylene of 72 % at 55 % ethane conversion. Overall, the catalytic results obtained indicate that the presence/absence and the nature of the promoter determines the catalytic performance of NiO based catalysts and the selectivity to ethylene can be explained on the basis of the electrochemical properties of the catalysts, correlating with parameters such as the density of acceptor defects (cationic vacancies) and the charge-transfer resistance at the interfacial active sites of the catalysts. Interestingly, the most selective catalyst (i.e., Nb-doped NiO) is highly robust as it presents stable catalytic performance after 24 h online and Ni2+ species are not reduced to Ni0 even working at high temperatures in N2O-free conditions., The funding received for this study from the Spanish Ministry of Science and Innovation, projects PID2021-126235OB-C31 and PID2021-126235OB-C33 (funded by MCIN/AEI/10.13039/501100011033 and FEDER funds) and projects TED2021-130756B-C31 and TED2021-129555B-I00 (funded by MCIN/AEI/10.13039/501100011033 and by "ERDF A way of making Europe" by the European Union NextGenerationEU/PRTR) , is acknowledged. BMT, PC, and JMLN also thank CEX2021-001230-S grant funded by MCIN/AEI/10.13039/501100011033. G. Sanchez-Garcia is also grateful to the Generalitat Valenciana (CIACIF/2021/010) and A. Perez-Calvo to Ministerio de Ciencia, Innovacion y Universidades (FPU23/02557) .

[EN] In this work, CuOx (x = 1 and 2) nanostructures have been synthesized by electrochemical anodization in
ethylene glycol based electrolytes using oxalic acid or NaF (with or without NaOH) as complexing agents.
The influence of hydrodynamic conditions and time during anodization of copper have also been evaluated.
A comprehensive morphological, structural, electrochemical and photoelectrochemical characterization
of the nanostructures has been performed. The results revealed the convenient use of oxalic acid
and 250 rpm for 5 minutes during electrochemical anodization to obtain homogeneous CuOx nanostructures
formed by spheres with Cu2O as a predominant phase. Using this nanostructure as a photocathode
for N2O photoelectron-reduction, almost 100% of N2O removal was achieved after 1 h, showing
the improvement of the photoelectrochemical approach vs. the photo or the electro performance, The authors would like to acknowledge the Ministerio de Ciencia e Innovacion-Agencia Estatal de Investigacion through the projects PID2021-126235OB-C33 and TED2021-129555B-I00. The authors also thank the Generalitat Valenciana for CIAICO/2021/094, CIGRIS/2022/198, and CIGE/2022/166 and for the financial support (CIACIF/2021/010).

CuOx (x = 1 and 2) nanostructures have been synthesized by electrochemical anodization in ethylene glycol based electrolytes using oxalic acid or NaF (with or without NaOH) as complexing agents. The influence of hydrodynamic conditions and time during anodization of copper have also been evaluated. An electrochemical and photoelectrochemical characterization of the nanostructures has been performed.

[EN] In the present article we show that, although the reflux method is not common for the synthesis of multicomponent MoVTeNbO catalysts, an optimized reflux synthesis of metallic precursors leads to efficient materials for the oxidative dehydrogenation of ethane and the selective oxidation of propane into acrylic acid, with the results at the same level as those of the best catalysts reported in the literature to date. It has been demonstrated that the reflux temperature is of paramount importance to achieve active and selective catalysts. Thus, the incorporation of vanadium and niobium to a polyoxometalate in the catalyst precursors is favored by refluxing at 110 & DEG;C, promoting the formation of the desired orthorhombic M1 phase. Additionally, the incorporation in the synthesis gel of cations such as ammonium or methylammonium provokes a further improvement of the catalytic performance whenever the activation procedure is carefully controlled., The authors gratefully acknowledge the financial support by the Ministerio de Ciencia e Innovacion of Spain, MINECO/FEDER (Projects: PID2021-126235OB-C31, PID2021-126235OB-C33, TED2021-130756B-C32 and TED2021-129555B-I00). F. Ivars-Barcelo gratefully acknowledges the support from "Ramon y Cajal" excellence program for recruitment (Ref.: RYC2020-029470-I/AEI/10.13039/501100011033).

[EN] Catalysts based on Ni-Me (Me = Co, Nb) supported on gamma-Al 2 O 3 were prepared by the coprecipitation-chemical deposition method via reflux, and hydrothermal method for oxidative dehydrogenation of ethane. For coprecipitation method, ammonia and urea were used as precipitating agents. In both methods, the Ni content was 30 wt.%, whereas that of Me (Co, Ni) was 5 wt.%. The activity and selectivity towards ethylene appeared to depend strongly on the composition of the catalysts and, interestingly, on the preparation conditions. In the present article, it is shown that mixed hydrothermal samples using urea showed the best performance. Specifically, the hydrothermally prepared NiNb/gamma-Al2O3 gamma-Al 2 O 3 sample was the one that showed the highest values. The introduction of Nb to Ni framework allowed to enrich with nucleophilic oxygen sites displayed via X-ray photoelectronic spectra (XPS) which lead to the formation of low reducible and selective sites., The authors thank the following institutions for funding the projects: FONDECYT: contract 138-2019, project No. 237-2015-FONDECYT, Project 219-2015-FONDECYT; and Spanish Ministry of Economy and Competitiveness, MINECO/FEDER (PID2021-126235OB-C31, PID2021-126235OB-C33) .

[EN] Multicomponent MoVTeNbO catalysts containing the orthorhombic M1 phase are highly active for the oxidative dehydrogenation (ODH) of ethane using O2 as oxidant, but their performance with N2O is strongly limited by the low efficiency of N2O decomposition capacity of the M1 catalyst. To overcome this limitation, we propose a strategy based on decoupling N2O decomposition from ethane oxidative dehydrogenation in a tandem reactor; in which N2O is decomposed in an upstream bed prior to contacting ethane with the M1 catalyst. Two different N2O decomposition catalysts were evaluated, i.e., CeO2 and a Cs-doped cobalt oxide (Cs-Co3O4), along with M1 catalyst. While with CeO2 the catalytic performance of the M1 catalyst was improved (by efficiently generating reactive oxygen species from N2O), with the Cs-Co3O4 we observed near-complete N2O conversion, leading to significantly higher ethane conversion and enhanced olefin yields of the subsequent M1 catalyst. In addition, different reactor configurations show that physical separation of both processes is essential to maximize performance, enabling high ethane conversion and ethylene selectivity at moderate temperatures. Characterization of fresh and spent catalysts indicates that performance is governed by the dynamic redox state of the M1 surface, strongly dependent on the oxidizing environment. These results demonstrate that decoupling oxidant generation from hydrocarbon conversion is an effective strategy for N2O valorization and selective ethane ODH., We thank: Spanish Ministry of Science and Innovation: PID2021-126235OB-C33 grants funded by MCIN/AEI/10.13039/501,100,011,033, PID2021-126235OB-C31 and CEX2021-001,230-S grants funded by MCIN/AEI/10.13039/501,100,011,033 Generalitat Valenciana (GVA): CIACIF/2021/010 grant.

[EN] This study reports the bio-mediated synthesis of tungsten trioxide nanostructures from aqueous extracts of Melia
azedarach (L.) dry leaves. The synthesis was carried out by electrochemical anodization of tungsten foils in the
presence of different volume percentages of leaves extracts. These nanostructures were afterwards completely
characterized by Field-Emission Scanning Electron Microscopy (FESEM), X-Ray Diffraction (XRD), High-
Resolution Transmission Electron Microscopy (HR-TEM), impedance measurements, linear sweep voltammetry
in the presence of simulated solar light and UV-Vis spectroscopy. Finally, these nanoelectrodes were used as
(photo)electrocatalysts in the photoelectrochemical water splitting process to obtain green hydrogen and as
anodes in Li-ion rechargeable batteries. Nanostructures fabricated with 5% M. azedarach leaves extract provided
the best (photo)electrocatalytic behavior for both applications, since in that biogenic electrolyte, thin nanorods
arranged in very porous and spongy layers were formed. Therefore, the significant increase in specific surface
area found for nanostructures fabricated following this green route, in comparison with the blank sample (i.e.,
nanostructure formed following a non-green route), was essential to enhance their performance as promising
efficient (photo)electrocatalysts., M. Erans is grateful for Grant RYC2021-031428-I funded by MCIN/AEI/10.13039/501100011033 and by European Union NextGenerationEU/PRTR. Authors would also like to acknowledge the Generalitat Valenciana for CIAICO/2021/094, CIGRIS/2022/198 and CIGE/2022/166. Authors also would like to acknowledge the Ministerio de Ciencia e Innovacion-Agencia Estatal de Investigacion through the projects PID2021-126235OB-C33 MCIN/AEI/10.13039/501100011033/FEDER Una manera de hacer Europa, UE and TED2021-129555B-I00/AEI/10.13039/501100011033/Union Europea NextGenerationEU/PRTR. Thanks to SCSIE-UV for assistance in characterization of materials.

[EN] In this work, a nanostructured WO3 photoanode has been used for photoelectrochemical H-2 production and CO2 reduction. In particular, we provide a novel method to synthesize tungsten oxide catalysts by anodization of tungsten using an ionic liquid, [EMIN][BF4], as electrolyte in hydrodynamic conditions. We found that the use of appropriate hydrodynamic conditions (200-400 rpm) provides larger and more homogenous nanostructures with higher surface area. All this leads to better morphological and electrochemical properties. An excessive rotation during the synthesis (600 rpm) breaks the uniformity of the morphology of the nanostructures, thus hindering the photoelectrochemical performance. This way, the use of an optimized WO3 photoanode has shown excellent potential for photoelectrocatalytic water splitting. Moreover, these nanostructures also present good performance in the photoelectrocatalytic CO2 reduction, leading to the main formation of acetic acid, formic acid, and methanol. In fact, after only 6 h in continuous mode, a remarkable formic acid concentration of 190 mu mol/L at 6 h has been obtained. Moreover, we have illustrated the great importance of the anode during the PEC reaction, significantly influencing the concentration of the obtained products owing to the electrons and protons transferred from the oxygen evolution reaction (OER)., This research was funded by the Ministerio de Ciencia e Innovacion-Agencia Estatal de Investigacion through the projects PID2021-126235OB-C33 MCIN/AEI/10.13039/501100011033/FEDER Una manera de hacer Europa, UE P and TED2021-129555B-I00/AEI/10.13039/501100011033/Union Europea NextGenerationEU/PRTR and by the European Union NextGenerationEU/PRTR. A. Perez-Calvo is also grateful to Ministerio de Ciencia, Innovacion y Universidades (FPU23/02557), and G. Sanchez-Garcia to the Generalitat Valenciana (CIACIF/2021/010).

[EN] Hydrothermally prepared Mo-V-Sb mixed oxides doped with alkali metal cations (Li+, Na+, K+, Rb+, or Cs+) show a significantly improved catalytic behavior in the oxidative dehydrogenation of ethane (ODH) compared to conventional alkali metal-free MoVSbO catalysts. Initial selectivity to ethylene above 95 % was held up to 20 % of ethane conversion for all alkali metal promoted MoVSbO catalysts, as well as lower ethylene overoxidation at higher ethane conversion, with differences depending on the alkali metal employed. Thus, from Li to K, the enhanced catalytic performance follows a bottom-up trend as increasing the size of the cation. An intermediate behavior is observed though for the catalyst doped with Cs cations, with the highest atomic radius. The K-doped MoVSbO catalyst is the least prone to both ethane total oxidation and ethylene overoxidation, which enables up to 90 % selectivity to ethylene at ethane conversion higher than 65 %., This work was supported by the Ministerio de Ciencia e Innovacion of Spain (projects PID21-126235OB-C31 and PID21-126235OB-C33). F. Ivars-Barcelo also acknowledges the Ministerio de Ciencia e Innovacion of Spain by the support from the "Ramon y Cajal" excellence grant (Ref.: RYC2020-029470-I/AEI/10.13039/501100011033).

An electrochemical and photoelectrochemical characterization of WO3 nanostructures has been performed by means of Electrochemical Impedance Spectroscopy and Mott–Schottky measurements, as well as using cyclic voltammetry and Photocurrent density curves.

[EN] Non-pure primary Vanadyl petroporphyrins extracted from oil, i.e., PVP(Oil), have been impregnated on SBA-15 or on SiO2. For comparison, synthetic vanadyl octaethylporphine, VP(S), was also impregnated on the same siliceous materials. The characterization result of unsupported porphyrins and the catalysts, by FTIR and DRUV-vis, confirm the successful incorporation of the corresponding vanadyl porphyrins. Electrochemical and photoelectrochemical properties of these catalysts have been evaluated through Electrochemical Impedance Spectroscopy (EIS), Mott-Schottky (MS) and voltammetry tests. According to the results, primary vanadyl porphyrin extracted from oil, PVP(Oil), show better photoelectrochemical response, regardless of the support used (either SiO2 or SBA15), than synthetic ones, VP(S). Additionally, this study reveals that PVP(Oil) can be used as photoelectrocatalysts for methyl red (MR) degradation (a common organic dye), showing almost a complete degradation of (MR) using PVP(Oil)-SBA15 catalyst after 3 h. Interestingly, an increase of more than 25% in the kinetic constant for the photoelectrochemical degradation of MR is shown for the PVP(Oil) in comparison to the VP(S)., The funding received for this study from the Spanish Ministry of
Science and Innovation, Projects PID2021 126235OB-C31 and
PID2021 126235OB-C33 funded by MCIN/AEI/10.13039/
501100011033 and FEDER funds, and from the Ministry of Science and
Higher Education of the Republic of Kazakhstan (Project: AP23486934)
is acknowledged. This Special Issue is dedicated to honor the 10th International Symposium on Group V (IV and VI) Elements, a gathering of
international researchers, industry, young researchers, and students to
help shape the vision of the future for these elements.

[EN] MoVO, MoVTeO and MoVTeNbO mixed oxides, prepared hydrothermally and heat-treated in N2 at 400, 500 or 600 degrees C, are active and selective catalysts in the oxidative dehydrogenation (ODH) of ethane, although their catalytic behaviour strongly depends on the composition and the activation temperature of the material. Thus, the selectivity to ethylene over samples heat-treated at 400 or 600 degrees C, decreases according to the following trend: MoVTeNb-600 > MoV-400 > MoVTe-600 > MoVTe-400 > MoVTeNb-400 >> MoV-600 (with catalysts heat -treated at 500 degrees C presenting an intermediate performance). This catalytic performance can be explained to a high extent by the presence of the M1 phase in the best catalysts. Interestingly, the temperature of formation and decomposition of the M1 phase strongly depends on the chemical composition of the catalysts, leading to different trends depending on the heat-treatment temperature. Not only the presence of the M1 phase determines the catalytic performance but also the V4+/V5+ ratio in the surface of catalysts. Additionally, a comprehensive brand-new electrochemical characterization of the catalysts has been carried out for MoV-based samples with M1 phase. Accordingly, the best catalytic behaviour in terms of selectivity to ethylene in the ethane ODH was observed in those materials presenting higher charge-transfer resistances at the interfacial active parts and n-type semiconductivity with few O-vacancies. Besides, lower current densities obtained in cyclic voltammetries (related to low electrochemical activity) has been associated with higher selectivity in the ODH reaction., The funding received from the Ministerio de Ciencia e Innovación of Spain, MINECO/FEDER (Projects: PID2021-126235OB-C31, PID2021-126235OB-C33, TED2021-130756B-C32 and TED2021-129555B-I00), for this study is acknowledged. A.A. acknowledges Severo Ochoa Excellence Program for his fellowship (BES-2017-080329).