Ni Amount Research Articles

High Performance of Porous, Hierarchically Structured P2‐Na0.6Al0.11 − xNi0.22 − yFex + yMn0.66O2 Cathode Materials

AbstractSodium‐ion‐batteries (SIB) are a low‐cost alternative to currently used lithium‐ion batteries (LIB) but suffer from poor cycling stability. Spray drying provides porous, hierarchically structured particles of cathode active material (CAM) in large amounts, suitable for up‐scaling. Changing the chemical composition of the Na0.6Al0.11 − xNi0.22 − yFex + yMn0.66O2 layered oxides under identical synthesis conditions lead to differences in particle morphology, conductivities, sodium vacancy ordering, and phase transition, therefore influencing the electrochemical performance via several mechanisms. Here, a broad overview on these changes for samples with variable nickel and iron content is presented. With increasing iron content, the particle porosity is reduced and lower initial capacity is received for most cycling windows. Substituting half of the original Ni amount with Fe still leads to high capacities and improved cycling stability. The influence of Al as electrochemically inactive element becomes visible in stabilized cycling stability as well.

(Invited) Transition Metals in Ni/GDC for the Reversible Solid Oxide Cell Operation: Optimization of the Mo-Au-Ni Synergy and Further Enhancement Via Substitution of Mo with Fe

The study focused on the elucidation of the synergistic interaction of different wt.% loadings of Mo and Au in Ni/GDC, with the objective to find their optimum content for enhanced rSOC performance. In addition, the promoting effect of Fe in Ni/GDC was stabilized via co-deposition with Au and there is for the first-time comparison among the transition metal modifications of Mo-Au-Ni vs Fe-Au-Ni. A series of samples was prepared, where the content of Au varied between 1 and 3 wt.% and between 0.4 and 1 wt.% for Mo. Physicochemical characterization took place with XRF, BET, SEM, H2-TPR, TPH2O and in-situ H2O-XPS. The effect of the transition metals interaction on the performance of SoA Ni/GDC was investigated via electrochemical I-V and EIS measurements in rSOC operation, by applying different pH2O/pH2 mixtures in the temperature range of 900 – 800 oC. It was found that high Mo and/or Au wt.% content, results in larger Mo-Au-Ni particles and affects differently the bulk and surface interaction of the samples with H2O, as well as the Rohm and Rpol values of the fuel electrodes. The modified samples were less prone to bulk oxidation by H2O, while they exhibited higher surface oxidation of Ni and higher amount of Ce3+, compared to Ni/GDC. On the surface of the optimum 0.4wt.% Mo-1wt.%Au-Ni/GDC: (i) Ni was less oxidized, (ii) Au0 enrichment was more stable and (iii) Mo was more oxidized, overall affecting positively the Rpol versus the electrode with the higher loadings of 1 wt.% Mo-3 wt.% Au. The main degradation factor of the latter cell was ascribed to the increased Rohm . Finally, a new ternary 0.5 wt.% Fe-3 wt.% Au-Ni/GDC electrode is presented, which exhibited superior electrochemical rSOC performance and stability, compared to the optimum Mo-Au-Ni/GDC, highlighting the need for further research in the transition metals effect on SOCs.

Spectroscopic Study on CdS/Ni/KNbO3: Confirming Ni Effect to Photocatalytic Activity.

Herein, we report the structural and photophysical properties of CdS/Ni/KNbO3 composites with a quantum yield for photocatalytic H2 generation that is CdS and Ni amount dependent. The nonstoichiometric KNbO3 (1:1.1) structure indicates the defect at the K site, which is Ni-occupied during its deposit process. It exhibits a tendency like a Ni-doped characteristic up to 0.1 wt % Ni and then forms a Ni cluster in case the Ni amount exceeds 0.1 wt %. The related structural and photophysical properties of CdS/Ni/KNbO3 are examined with Fourier transform infrared, X-ray diffraction, ultraviolet-visible absorption, and luminescence spectral analysis. It demonstrates the CdS/Ni/KNbO3 composites to be an efficient light conversion caused by efficient charge/electron transfer between KNbO3 and CdS via doped Ni. The photocatalytic activity of CdS/Ni/KNbO3 exhibits a CdS and Ni amount dependency. The best photocatalytic activity for H2 generation is obtained with 0.1 wt % Ni and 2.9 wt % CdS as it gradually declines with the excess Ni amount than 0.1 wt % caused by a formed Ni cluster.

Influence of precursor compounds on the structural and catalytic properties of CoNiMo/SBA-15 catalysts used in the hydrodesulfurization of dibenzothiophene

In the present research project, it was studied in detail how the incorporation of different precursor compounds and the supplementary addition of amounts of nickel in the MoS2 slabs can influence the structural and catalytic properties of trimetallic CoNiMo catalysts supported on SBA-15 mesoporous support with precise control of the amount and nature of the promoters. The catalysts were prepared by the incipient impregnation method using ammonium heptamolybdate and cobalt and nickel acetate, and nitrate as precursors adding nickel in molar amounts (5, 10, and 20%) of the cobalt atomic loading. Adding the Ni in small amounts allows us to keep the (Co + Ni)/(Co+Ni+Mo) molar ratio near 0.3. The catalysts formed were labeled according to the precursor compounds used (CoNixMo-Ac for acetates and CoNixMo-N for nitrates), where x is the percentage of nickel. Catalysts were then characterized by N2 adsorption-desorption isotherms, X-ray diffraction, high-resolution transmission electron microscopy, and X-ray photoelectron spectroscopy. Catalysts were tested in the HDS of dibenzothiophene (DBT).Results show a significant impact of adding small amounts of nickel and the type of precursor compounds used for the CoNiMo trimetallic catalysts on the final HDS activity. In the case of the catalysts prepared with cobalt and nickel acetates, it was observed that the initial reaction rate values increased as the amount of Ni increased, being the CoNi5Mo-Ac, the catalyst with the lower catalytic activity. Increasing the amount of Ni causes an increase in the HDS of DBT. In the case of the catalysts prepared with nitrates, it could be observed a similar effect. The catalyst with the higher catalytic activity in both series was the CoNi20Mo-Ac. These results agree with the TEM analysis in which a decrease in the slab length of the MoS2 could be regarded as the de Ni amount increase. This means that the type of precursor used has an essential effect on the catalysts since modify their properties and catalytic activity and suggests that the materials synthesized with acetate precursors can help to improve the intrinsic activity of the HDS sites.

Unravelling the role of the exchanged Ni amount in zeolites A and X for their thermal transformation into magnetic metal-ceramic nanocomposites

Magnetic zeolites with a Ni content of 4.80 and 6.20 wt%, were prepared by Ni-exchanging zeolites 4 A and 13×, respectively, and thermally treating the Ni-exchanged zeolites at 735–750 °C, under a reducing atmosphere. This thermal treatment gave rise to the formation of Ni0 nanoparticles dispersed in a ceramic matrix, which partially retained the zeolitic structure (about 50%). The obtained nanocomposites were fully characterized using atomic absorption spectrometry, X-rays powder diffraction (with synchrotron source) followed by Rietveld analysis, High-Resolution Transmission Electron Microscopy, N2 adsorption/desorption at −196 °C and magnetic measurements at both room temperature and low temperature. To highlight the effect of nickel content on the final properties of the nanocomposites, the features of the samples produced in this work were compared with the features of the nanocomposites obtained, in previous works, from the same zeolites loaded with a low (approx. 1%) and a high (approx. 15 wt%) Ni content.The most important result obtained here is that only by entering the intermediate Ni content of this work (4.80–6.20 wt%) it was possible to obtain real magnetic zeolites as the final product of the process. The low Ni content gave rise to a poor magnetic response, whereas the high Ni content resulted in the almost total destruction of the zeolite framework.

One-step solvothermal growth of NiO nanoparticles on nickel foam as a highly efficient electrocatalyst for hydrogen evolution reaction

Herein we report for the first time on the in situ solvothermal growth of NiO nanoparticles on nickel foam (NF) electrodes towards enhancing the active electrochemical area and, in turn, the hydrogen evolution reaction (HER). In particular, the Ni amount deposited on the NF electrode was thoroughly explored by varying the Ni precursor content (0–64 mmol of Ni(NO3)2·6H2O) during one-step solvothermal synthesis. A volcano-type dependency on Ni precursor amount was revealed, with the optimum performance being obtained by NiO@NF-16 (16 mmol Ni(NO3)2·6H2O). The NiO@NF-16 sample exhibited the lowest overpotentials |η10| = 109 mV, |η100| = 193 mV, the lowest Tafel slope (103.9 mV dec−1), and the highest current density during electrolysis (1947 mA cm−2). To gain insight into structure-performance relationships, the electrodes were thoroughly characterized by means of field emission scanning electron microscopy (FESEM), energy dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). It was revealed that the improved electrochemical characteristics of NiO@NF-16 electrode could be mainly attributed to the uniform growth and high dispersion of NiO nanoparticles on nickel foam, which, in turn, results in a high electrochemically active surface area (ECSA), which is ca. 55 times higher than that of NF electrode.

Transition metals in Ni/GDC for the reversible solid oxide cell operation: Optimization of the Mo-Au-Ni synergy and further enhancement via substitution of Mo with Fe

The study focused on the elucidation of the synergistic interaction of different wt.% loadings of Mo and Au in Ni/GDC, with the objective to find their optimum content for enhanced rSOC performance. In addition, the promoting effect of Fe in Ni/GDC was stabilized via co-deposition with Au and there is for the first-time comparison among the transition metal modifications of Mo-Au-Ni vs Fe-Au-Ni. A series of samples was prepared, where the content of Au varied between 1 and 3 wt.% and between 0.4 and 1 wt.% for Mo. Physicochemical characterization took place with XRF, BET, SEM, H2-TPR, TPH2O and in-situ H2O-XPS. The effect of the transition metals interaction on the performance of SoA Ni/GDC was investigated via electrochemical I-V and EIS measurements in rSOC operation, by applying different pH2O/pH2 mixtures in the temperature range of 900 – 800 °C. It was found that high Mo and/or Au wt.% content, results in larger Mo-Au-Ni particles and affects differently the bulk and surface interaction of the samples with H2O, as well as the Rohm and Rpol values of the fuel electrodes. The modified samples were less prone to bulk oxidation by H2O, while they exhibited higher surface oxidation of Ni and higher amount of Ce3+, compared to Ni/GDC. On the surface of the optimum 0.4 wt.% Mo-1 wt.%Au-Ni/GDC: (i) Ni was less oxidized, (ii) Au0 enrichment was more stable and (iii) Mo was more oxidized, overall affecting positively the Rpol versus the electrode with the higher loadings of 1 wt.% Mo-3 wt.% Au. The main degradation factor of the latter cell was ascribed to the increased Rohm. Finally, a new ternary 0.5 wt.% Fe-3 wt.% Au-Ni/GDC electrode is presented, which exhibited superior electrochemical rSOC performance and stability, compared to the optimum Mo-Au-Ni/GDC, highlighting the need for further research in the transition metals effect on SOCs.

Towards stable nickel catalysts for selective hydrogenation of biomass-based BHMF into THFDM

Selective transformation of BHMF (2,5-bis(hydroxymethyl)furan) to THFDM (tetrahydrofuran-2,5-dimethanol) over a variety of structured Ni/Sx-Z1−x catalysts was investigated. The effects of support, Ni loading, solvent, temperature, pressure, and particle size on the conversion and selectivity were studied. Among them, the 10 wt% Ni catalyst supported on the SiO2:ZrO2 weight ratio of 90:10 (10NiS90Z10) exhibits the best performance in terms of BHMF conversion and THFDM selectivity. Its good performance was attributed to its well-balanced properties, that depend upon the ZrO2 content of the support in combination with SiO2, the active Ni sites-support interaction, and acidity/basicity ratio of each catalyst resulting in different Ni dispersions. Importantly, the 10NiS90Z10 catalyst showed a stable selectivity to THFDM (>94%), with 99.4% conversion of BHMF during 2 h reaction time. Poor catalytic activity resulted from excessive ZrO2 content (>10 wt%). The structural, textural, and acidity properties of NiSi100−y-Zry catalysts, tuned by selectively varying the Ni amount from 5 to 15 wt%, were critically investigated using numerous material characterization techniques. Catalyst recycling experiments revealed that the catalyst could be recycled several times without any measurable loss of catalytic activity.

Theoretical study on the hydrogenation of furfural for furfuryl alcohol production over low Ni modified Cu catalysts

Cu-based catalysts are efficient for the upgrading of biomass-derived furfural (FF) to produce furfuryl alcohol (FOL), and a low amount of Ni doping is promising to improve the catalytic performance. Herein, Cu (111), Cu7Ni (111), and Cu3Ni (111) catalyst models were constructed. Density functional theory (DFT) calculations were applied to explore the effects of Ni on the FF hydrogenation mechanism by analyzing the FF adsorption configurations, adsorption energies, electronic structures of the adsorbed FF and the catalyst surfaces, as well as reaction pathways and energy barriers of FF hydrogenation. Ni doping promotes the charge transfer between the catalyst surface and FF, thus enhancing the adsorption capacity of the catalyst. The H2 dissociation ability can also be enhanced by the Ni modification. In the initial hydrogenation process, the aldehyde group of the adsorbed FF is easy to hydrogenate and thus contributing to the selective production of FOL. With the increase of the Ni amount, the competitiveness of the hydroxyalkyl intermediate (F–CHOH) involved pathway increases according to the gradually widened energy barrier gaps among the competing pathways. All in all, the Cu3Ni (111) catalyst has the best hydrogenation activity with an energy barrier of 8.99 kJ/mol.

Nickel Supported on Multilayer Vanadium Carbide for Dry Reforming of Methane

AbstractA multilayer vanadium carbide MXene (m‐V2C) was used as a robust oxy‐carbide support to prepare a series of Ni/m‐V2O3‐V2C catalysts with various Ni amounts by an impregnation method and used for dry reforming of methane (DRM). The results show that the Ni addition increases the catalyst alkalinity, and the interaction between the Ni metal and m‐V2C increases with increasing Ni amount. Ni/m‐V2O3‐V2C with a Ni amount of 13 wt% showed optimal CH4 and CO2 conversions of 94 % and 89 %, respectively. In addition, 13Ni/m‐V2O3‐V2C exhibits excellent catalytic stability and anti‐coking ability in a 90‐hour stability test, which is attributed to the strong metal‐support interaction. In situ DRIFTS analysis showed that methane activated on the Ni particles generates CHx and H, while CO2 interacts with m‐V2O3‐V2C to form carbonates on Ni/m‐V2O3‐V2C; carbonate species come into contact with methane pyrolysis products and quickly form formate species, which are further decomposed into CO.

Green and blue materials for the ceramic industry from pink MgCoxNi1-xSiO4 (0 ≤ x ≤ 1) solid solutions

In this study, MgCoxNi1-xSiO4 (0.0 ≤ x ≤ 1.0) solid solutions with an olivine structure were synthetized via the chemical coprecipitation method and materials with a smaller M(II) (M = Co, Ni) amount than Co2SiO4 and Ni2SiO4 compounds were obtained. At 1200 °C, the Co(II) and Ni(II) were randomly distributed in the MgCoxNi1-xSiO4 (0.0 ≤ x ≤ 1.0) solid solutions with the olivine structure, but the occupation of Co(II) and Ni(II) ions in M1 (4a) octahedral sites was obtained at a higher level than in M2 (4c) octahedral sites. The Mg(II) ions prefer the M2 sites. This preference explains the main contribution of the M1 sites in spectra of octahedral Co(II) ions and the M1-O and M2-O distances jointly explain the pink colour of the MgCoxNi1-xSiO4 (0.0 ≤ x ≤ 1.0) solid solutions, while the colour of Co2SiO4 is blue. Spectra can be interpreted as the sum of Ni(II) and Co(II) ions in octahedral sites. When these solid solutions are enamelled, the pink colouring changes to green or blue because of the presence of tetrahedral Co(II).

H2 produced by catalytic reforming of acetic acid over Ni/char catalyst recycled from the biochar adsorption purification of simulated Ni electroplating wastewater

• Double-green of purifying electroplating Ni wastewater and producing H 2 was realized. • Surface complexation and ions exchange mechanisms of biochar promoted Ni 2+ removal. • The recycled Ni on biochar increased the H 2 yield by 15 times. • Two-step activation of steam and H 2 greatly improved double-green performance. • Steam activation increased surface area, Ni dispersion and surface Ni amount. The new method of using biochar to purify nickel-simulated electroplating wastewater and subsequent preparation of a Ni-based catalyst to produce H 2 in bio-oil reforming reaction is proposed. This process aims to realize the double-green of wastewater treatment and H 2 production. Different types of biochar (rice straw, rice husk and cotton stalk) were used. The results indicated that rice straw char (RSC) performed the highest Ni 2+ removal efficiency due to ash components' high ion exchange capacity and high complexation ability of oxygen-containing functional groups. Then the adsorbed RSC was reduced and recycled to prepare Ni/RSC catalyst. Compared with the unadsorbed RSC, the recycled metal Ni remarkably improved the catalytic activity. The average carbon conversion of acetic acid at 600 °C was increased to 76.26% and H 2 yield was increased by 15 times. To further enhance the double-green performance, a two-step activation process was implemented. The biochar was firstly corroded by steam addition (5%, 15% and 25%) and then the adsorbed biochar was reduced by H 2 . After that, the surface area, oxygen-containing functional groups and exchangeable cations of biochar were remarkably enhanced, which increased the Ni removal efficiency to reach 100%. Besides, the formed metal Ni with the higher metal dispersion and smaller Ni particle size improved the reforming of acetic acid. The activation by adding 25% steam further improved carbon conversion by 13.34% and H 2 yield by 60.47%.

Renewable hydrogen production via glycerol steam reforming over Ni/CeO2 catalysts obtained by solution combustion method: The effect of Ni loading

A series of nanocrystalline Ni/CeO2 catalysts with various Ni content was prepared by urea-nitrate combustion synthesis and evaluated in glycerol steam reforming for renewable H2 production. The as-prepared, reduced and spent catalysts were characterized by various analytical techniques such as XRD, N2-physisorption, SEM–EDX, TEM–HAADF and SAED, H2-TPR, XPS, Raman, and DTA–TGA. NiO is predominantly in the X-ray amorphous state (particle size 2–4 nm regardless of the Ni amount), which is retained for Ni0 particles after reduction by H2. Significant fraction of NiO(Ni0) is localized between CeO2 aggregates. An increase in the Ni content leads to inhibition of the agglomeration of CeO2 crystallites and increase in CeO2 defectiveness up to 6.8 wt% Ni; formation of CeO2(Ni2+) solid solution at 8.7 wt% Ni, which decomposes upon reduction. The sample containing 6.8 wt% Ni exhibits the best combination of Ni content and dispersion, CeO2 defectiveness, glycerol conversion, H2 yield, selectivity to H2 and CO2 and has low selectivity to hydrocarbons. TEM and DTA–TGA revealed the formation of amorphous, graphite-like, and fibrous coke depending on the Ni amount. This formation leads to accelerated deactivation due to partial agglomeration of Ni0 particles and encapsulation of amorphous nickel.

In situ synthesis by organometallic method of vulcan supported PdNi nanostructures for hydrogen evolution reaction in alkaline solution

Pd and Pd-based catalysts for hydrogen production remain the best alternative to Pt substitution because of similarities in their electronic structure and more abundant reserves. In this work, it was carried out the in-situ synthesis of Pd x Ni 1-x /C electrode materials (x = 0, 30, 50, 70 and 100 wt%) by the displacement of ligands from organometallic compounds followed by an annealing process at 300 °C in Ar atmosphere. The electrocatalytic performance of these materials was evaluated on the hydrogen evolution reaction in alkaline medium (1 M KOH). The results showed that annealing process, after the synthesis of stabilized nanostructures by organometallic method, did not affect the particle size (4.27 ± 1.14 to 4.62 ± 1.59 nm) and dispersion (25.75–27.07%) of the alloyed nanostructures. The modification of Pd electronic features with low Ni amount facilitates the adsorption of the hydrogen on the bimetallic active surface of the catalysts. The PdNi alloys, especially Pd 70 Ni 30 /C, tend to display the overpotential of HER to more positive values in comparison with Pd/C catalysts. This behavior is clearly correlated with an improvement by the synergistic effect between the components, which in turn enhance the electrochemical surface area (ECSA) and the real area. Either the hydrogen adsorption resistance and charge transfer resistance are dependent of the Ni amount, due to Ni influences ion/atom recombination or hydrogen desorption. • Stabilized particles of binary Pd x Ni 1-x alloys by organometallic compounds method. • Annealing process does not affect particle size, stabilization and dispersion. • Ni incorporation provokes a displacement in fcc peaks confirming alloy formation. • Pd 70 Ni 30 /C display more positive HER overpotentials in comparison with Pd/C.

Tomato (Solanum lycopersicum L.) accumulation and allergenicity in response to nickel stress

Vegetables represent a major source of Ni exposure. Environmental contamination and cultural practices can increase Ni amount in tomato posing significant risk for human health. This work assesses the tomato (Solanum lycopersicum L.) response to Ni on the agronomic yield of fruits and the related production of allergens. Two cultivars were grown in pots amended with Ni 0, 30, 60, 120, and 300 mg kg−1, respectively. XRF and ICP-MS analyses highlighted the direct increase of fruit Ni content compared to soil Ni, maintaining a stable biomass. Leaf water content increased at Ni 300 mg kg−1. Total protein content and individual allergenic components were investigated using biochemical (RP-HPLC and N-terminal amino acid sequencing) and immunological (inhibition tests of IgE binding by SPHIAa assay on the FABER testing system) methodologies. Ni affected the fruit tissue concentration of pathogenesis-related proteins and relevant allergens (LTP, profilin, Bet v 1-like protein and TLP). This study elucidates for the first time that tomato reacts to exogenous Ni, uptaking the metal while changing its allergenic profiles, with potential double increasing of exposure risks for consumers. This evidence highlighted the importance of adequate choice of low-Ni tomato cultivars and practices to reduce Ni uptake by potentially contaminated matrices.

Spectroscopic and magnetic properties of Co0.15Al0.25-xNi0.6+xFe2O4nanocomposites aided by silica for prohibiting pathogenic bacteria during sewage handling

CoAlNiFe2O4 nanomagnetic are an important class of nanocomposite oxides that possess high surface area, excellent magnetic features, tunablesize and shape, surface active sites, and the facility with which they can be functionalized. Therefore, Opto-magnetic Co0.15Al0.25-xNi0.6+xFe2O4 (x = 0.0, 0.3, 0.11, 0.25) nanocomposites aided by silica were prepared via citrate/ethylene glycol sol–gel processes and calcined at 650 °C.Concurrently, the increase of Ni+ nanoparticles on the structural, morphological, optical, and magnetic features of the Co0.15Al0.25-xNi0.6+xFe2O4/SiO2 porous magnetic nanocomposites is examined by the XRD, SEM, and FT-IR spectroscopy. Indirect energy gap value, refractive index, optical dielectric constant, and optical electronegativity were estimated. The Coercivities for the magnetic nanocomposites within ∼ 250–350 Oe and saturation of ∼ 30–35 emu/g can be adjusted using the appropriate Ni amount. The obtained results support the nanocomposites in applications for high-performance optoelectronic and opto-magnetic devices. The highest inhibition zone of all tested bacteria for CANFSO was doped with 0.25 Ni NPs; the diameters of the inhibition zone for E.coli O157, Salmonella typhimurium, Staphylococcus aureus, and Bacillus subtilis were 31, 34, 29, and 27 mm around the discs and 34, 36, 31, and 29 mm around the wells, respectively. The effective dosage (300 ppm) of each nanocomposite was injected to disinfect sewage during different retention times (0–60 min). The results confirmed that CANFS-0.25Ni could completely eliminate all bacterial pathogens in the sewage sample.

LaFeO3 Modified with Ni for Hydrogen Evolution via Photocatalytic Glucose Reforming in Liquid Phase

In this work, the optimization of Ni amount on LaFeO3 photocatalyst was studied in the photocatalytic molecular hydrogen production from glucose aqueous solution under UV light irradiation. LaFeO3 was synthesized via solution combustion synthesis and different amount of Ni were dispersed on LaFeO3 surface through deposition method in aqueous solution and using NaBH4 as reducing agent. The prepared samples were characterized with different techniques: Raman spectroscopy, UltraViolet-Visible Diffuse Reflectance Spettroscopy (UV–Vis-DRS), X-ray Diffraction (XRD), X-ray Photoelectron Spectroscopy (XPS), X-ray Fluorescence (XRF), Transmission Electron microscopy (TEM), and Scanning Electron microscopy (SEM) analyses. For all the investigated photocatalysts, the presence of Ni on perovskite surface resulted in a better activity compared to pure LaFeO3. In particular, it is possible to identify an optimal amount of Ni for which it is possible to obtain the best hydrogen production. Specifically, the results showed that the optimal Ni amount was equal to nominal 0.12 wt% (0.12Ni/LaFeO3), for which the photocatalytic H2 production was equal to 2574 μmol/L after 4 h of UV irradiation. The influence of different of photocatalyst dosage and initial glucose concentration was also evaluated. The results of the optimization of operating parameters indicated that the highest molecular hydrogen production was achieved on 0.12Ni/LaFeO3 sample with 1.5 g/L of catalyst dosage and 1000 ppm initial glucose concentration. To determine the reactive species that play the most significant role in the photocatalytic hydrogen production, photocatalytic tests in the presence of different radical scavengers were performed. The results showed that •OH radical plays a significant role in the photocatalytic conversion of glucose in H2. Moreover, photocatalytic tests carried out with D2O instead of H2O evidenced the role of water molecules in the photocatalytic production of molecular hydrogen in glucose aqueous solution.

Construction of nickel nanoparticles embedded in nitrogen self-doped graphene-like carbon derived from waste grapefruit peel for multifunctional OER, HER, and magnetism investigations

Effective biomass waste utilization to alleviate the environmental pollution is significant for the sustainable development of human society and nature. Herein, in this work, waste grapefruit peels with wrinkled hollow structure and abundant reactive groups were used to fabricate a series of multifunctional nickel nanoparticles embedded in nitrogen self-doped graphene-like carbon nanocomposites (Nix @NGC, where “x” represents the amount of Ni) via a simple and convenient impregnation-carbonization strategy. The reaction temperature and Ni amount were tuned to investigate their influences on structure and performance. When evaluated as electrocatalysts in alkaline oxygen evolution and hydrogen evolution reactions, the optimal Ni0.20 @NGC-700 exhibits low overpotentials of 350 and 165 mV and moderate Tafel slopes at current densities of 20 and 10 mA cm−2, respectively. Also, the as-prepared Ni0.20 @NGC-750 shows an excellent magnetic ability with a high saturation magnetization strength of 47 emu g−1 and a low coercivity of 83 Oe. This study may provide a simple and sustainable approach for the development of environmental and cost-effective nanocomposites with excellent electrical and magnetic performance.

Synthesis of single phase LaMn1−XNiXO3 perovskite material

Ni substituted lanthanum manganite of LaMn1−XNiXO3 (x = 0.2, 0.4, 0.5, 0.6, 0.7) of a single phase perovskite structure was synthesised through sol-gel technique. The effect of Ni substitution by varying Ni and Mn amount ratios over LaMn1−XNiXO3 materials were studied. The physio-chemical characteristics like crystallinity were confirmed by XRD, surface area by BET analysis, metallic surface area by CO chemisorption. The optimal level of Ni substitution increases surface area, pores volume and metallic surface area, which leads highly stability. The oxygen vacancies and rapid migration of lattice oxygen from the bulk toward the surface was observed over LaMn0.4Ni0.6O3 compared to other perovskite materials. The LaMn0.4Ni0.6O3 perovskite materials show high surface area, metallic area with absorbed oxygen due to threshold Ni and Mn ratio leads the perfect synergic balance.

Plasma Driven Exsolution for Nanoscale Functionalization of Perovskite Oxides.

Perovskite oxides with dispersed nanoparticles on their surface are considered instrumental in energy conversion and catalytic processes. Redox exsolution is an alternative method to the conventional deposition techniques for directly growing well-dispersed and anchored nanoarchitectures from the oxide support through thermochemical or electrochemical reduction. Herein, a new method for such nanoparticle nucleation through the exposure of the host perovskite to plasma is shown. The applicability of this new method is demonstrated by performing catalytic tests for CO2 hydrogenation over Ni exsolved nanoparticles prepared by either plasma or conventional H2 reduction. Compared to the conventional thermochemical H2 reduction, there are plasma conditions that lead to the exsolution of a more than ten times higher Ni amount from a lanthanum titanate perovskite, which is similar to the reported values of the electrochemical method. Unlike the electrochemical method, however, plasma does not require the integration of the material in an electrochemical cell, and is thus applicable to a wide range of microstructures and physical forms. Additionally, when N2 plasma is employed, the nitrogen species are stripping out oxygen from the perovskite lattice, generating a key chemical intermediate, such as NO, rendering this technology even more appealing.