Size Of Ni Nanoparticles Research Articles

Investigation of Shear Strength and Microstructure Formation of Joined Ni Superalloys Using Ni Nanopastes.

By using Ni nanoparticles, the bonding of Ni base superalloys can be achieved with shear strengths well above 200 MPa in a joining process at comparatively low temperatures between 675 °C and 975 °C. This is enabled due to the high surface-to-volume ratio of nanoparticles, which leads to distinctly lower melting and sintering temperatures than those of the corresponding bulk material. The nanoparticles in this study are employed in high-metal nanopastes, whereby different chemical compositions of the pastes and different sizes of Ni nanoparticles were investigated. The results for the joining of Ni base superalloys showed that both size and composition had a significant influence on the achievable strengths. In addition, an extensive examination was conducted to reveal the influence of the process parameters joining temperature, holding time and joining pressure on the shear strengths as well as microstructure. It was shown that the temperature exerted the most influence on the strengths and the microstructure. The joining pressure also had a significant influence. The holding time, on the other hand, did not have a major influence on the strengths and in some cases even showed an unexpected behavior, as the values decreased for some combinations with longer holding time.

In-situ synthesis of ultra-small Ni nanoparticles anchored on palygorskite for efficient reduction of 4-nitrophenol

4-nitrophenol (4-NP) is an environmental pollutant with high toxicity and strong stability, which is difficult to degrade naturally. Reduction of 4-NP to 4-aminophenol (4-AP), an important chemical intermediate, is an economical and green method. The reduction process demands high-efficient catalysts, and ultra-small metal nanoparticles (NPs) are the great potential ones. Herein, ultra-small and monodisperse Ni nanoparticles (NiNPs) (5.1 nm) were successfully anchored on palygorskite (Pal), using nickel silicate (NiSi) as a welding-like joint, and the ultimate catalysts were NiNPs/NiSi/Pal nanocomposites. The NiNPs were in-situ reduced from the NiSi precursor, which was previously and in-situ grown on Pal. The size of NiNPs was adjustable by the NiSi precursor, while the size of the NiSi precursor was controlled by the etching degree cations of the crystal structure of Pal. The etching degree affected the amounts of octahedral released from Pal, and thus affected the amounts of freshly exposed SiO- bonds, which could capture Ni2+ ions, form SiONi bonds and promote the generation of NiSi. The as-prepared NiNPs/NiSi/Pal nanocomposites exhibited excellent catalytic activity for the reduction of 4-NP (52.67 × 10-3 s−1), and satisfactory recyclability. The excellent catalytic performance is mainly attributed to the full exposure of ultra-small NiNPs, which provides enough active sites and enables fast electron transfer between the catalysts and substrates. It is expected that the work could develop a new avenue for designation of ultra-small and monodisperse non-precious metal NPs, and contribute to the treatment of waste water containing 4-NP.

Roles of Al2O3 coating layer on an ordered mesoporous Ni/m-Al2O3 for combined steam and CO2 reforming with CH4

To enhance catalytic and thermal stability of Ni nanoparticles for a combined steam and CO2 reforming with CH4 (CSCR), the utilization of an ordered mesoporous Al2O3 support with ∼6 nm of average pore diameter (Ni/m-Al) was proposed in terms of spatial confinement effects of the Ni nanoparticles with the help of successive Al2O3 overlayer protective layers (Ni/m-Al@Al). At an optimal amount of Al2O3 coating layers less than ∼3 wt%, the much higher catalytic activity and stability were observed on the Ni/m-Al@Al(3). The synergy effects of Al2O3 overlayers on the ordered mesoporous Ni/m-Al were mainly attributed to the formation of strongly interacted Ni-Al2O3 interfaces as supported by its higher XPS binding energy in the spatially restricted mesoporous m-Al channels with the protective metal oxide overlayers. Those structures were also responsible for the suppressed migrations of the spatially confined Ni nanoparticles to the outer m-Al surfaces by Al2O3 protective overlayers, which resulted in an excellent long-term stability with small coke depositions by preserving the original Ni nanoparticle sizes.

Fabrication of high-performance non-enzymatic sensor by direct electrodeposition of nanomaterials on porous screen-printed electrodes

BackgroundScreen-printed sensors can be easily fabricated and have advantages of cost-effectiveness, low instrument demand, and decentralized fabrication. However, they often suffered from low reproducibility and conductivity, restraining them from practical applications. MethodThis study demonstrated a high-performance sensor with large surface area, high conductivity, wide detection range, and consistent catalytic kinetics using screen printing and electrodeposition. The large surface area was achieved by blending sacrificer into carbon paste to fabricate porous electrodes. Two steps of electrodeposition decorated the porous electrode surface with graphene and nickel nanoparticles to enhance conductivity and enable catalytic reactions of lactate. Significant findingsElectrodeposition achieved consistent size and spatial distributions of graphene and Ni nanoparticles, enabling high conductivity and reactivity. The deposited nickel nanoparticles were a mixture of Ni2+ and Ni3+ derivatives, resulting in a high variation in response currents. By oxidizing the Ni-derivatives NPs to a uniform state of nickel hydroxide, the sensor attained a highly linear detection with an 83% lower standard error. Additionally, the improved sensor had an impressive linear detection range from 0.5 to 60 mM. The fabrication was easy to follow and had a minimum demand for the instrument, making it particularly valuable for practical applications in regions with limited resources.

Effect of calcination temperature on the electrochemical performance of nickel nanoparticles on carbon coated porous silicon nanospheres anode for lithium-ion batteries

Si/C composite has been widely studied as high performance anode for lithium-ion batteries (LIBs) due to its high capacity and abundant resource. However, its practical application is still hampered by the limited electronic conductivity. Herein, Ni nanoparticles are introduced on Si/C composite by calcining porous Si covered with Ni2+-polydopamine complexes in this paper. The effect of the calcination temperature on the structure and electrochemical property of the obtained Si@C-Ni composite anode is systematically studied. When the calcination temperature is 550 °C, the Si@C-Ni shows the best electrochemical performance (a high capacity of 1622.9 mA h g−1 at 0.2 A g−1 after 100 cycles and an excellent rate performance of 1140 mA h g−1 at 6.4 A g−1). Its outstanding electrochemical performance of Si@C-Ni-550 is related to the optimized size and uniform dispersion of Ni nanoparticles which can offer additional electron highway, boosting the electronic conductivity of Si/C composite. Higher calcination temperature (≥650 °C) leads to the rapid increase of Ni nanoparticles size which results in Ni aggregation on carbon, reducing the cycling stability and rate capability of Si@C-Ni. Our work offers a guide to prepare high performance metal-rich Si/C composite anode with appropriate synthetic temperature for LIBs.

Hydriding pathway for Ni nanoparticles: Computational characterization provides insights into the nanoparticle size and facet effect on layer-by-layer subsurface hydride formation

Nickel and its alloys are often used in the form of nanostructured materials, e.g., as catalysts for hydrogenation reactions, for hydrogen-storage applications, and as battery materials. This study focuses on subsurface hydride (NiHx) formation in Ni nanoparticles. The pressure at which hydrogen is incorporated within the nanoparticle surface is probed using grand canonical Monte Carlo (GCMC) simulations. An important observation is that the Ni nanoparticle size can have a significant effect on the hydride formation. Unlike bulk Ni, which forms the hydride phase at very high H2 pressures, subsurface NiHx can form at significantly lower pressures with 2.7–9.1 nm particles. The (111) and (100) facets and facet edges of these nanoparticles possess remarkably different H incorporation characteristics compared to the nanoparticle core. The easier H-absorption in Ni nanoparticles is explained in terms of a nucleation-and-growth process, which begins at the facet edges and proceeds towards the interior of the nanoparticle. The NiHx and Ni phases co-exist in nanoparticle systems, which is not observed in bulk Ni. A computational characterization approach is used to gain insights into the layer-by-layer H incorporation, which can be valuable for devising material preparation strategies for adsorption-based hydrogen storage and catalysis.

In Situ Studies of Single-Nanoparticle-Level Nickel Thermal Oxidation: From Early Oxide Nucleation to Diffusion-Balanced Oxide Thickening.

High-temperature oxidation mechanisms of metallic nanoparticles have been extensively investigated; however, it is challenging to determine whether the kinetic modeling is applicable at the nanoscale and how the differences in nanoparticle size influence the oxidation mechanisms. In this work, we study thermal oxidation of pristine Ni nanoparticles ranging from 4 to 50 nm in 1 bar 1%O2/N2 at 600 °C using in situ gas-cell environmental transmission electron microscopy. Real-space in situ oxidation videos revealed an unexpected nanoparticle surface refacetting before oxidation and a strong Ni nanoparticle size dependence, leading to distinct structural development during the oxidation and different final NiO morphology. By quantifying the NiO thickness/volume change in real space, individual nanoparticle-level oxidation kinetics was established and directly correlated with nanoparticle microstructural evolution with specified fast and slow oxidation directions. Thus, for the size-dependent Ni nanoparticle oxidation, we propose a unified oxidation theory with a two-stage oxidation process: stage 1: dominated by the early NiO nucleation (Avrami-Erofeev model) and stage 2: the Wagner diffusion-balanced NiO shell thickening (Wanger model). In particular, to what extent the oxidation would proceed into stage 2 dictates the final NiO morphology, which depends on the Ni starting radius with respect to the critical thickness under given oxidation conditions. The overall oxidation duration is controlled by both the diffusivity of Ni2+ in NiO and the Ni in Ni self-diffusion. We also compare the single-particle kinetic curve with the collective one and discuss the effects of nanoparticle size differences on kinetic model analysis.

Embedding high loading and uniform Ni nanoparticles into silicalite-1 zeolite for dry reforming of methane

Embedding Ni nanoparticles (NPs) into supports has been widely accepted as one of solutions for Ni confinement, but high loading usually stands on the opposite of being well dispersed and encapsulated. Herein, we developed a controlled ‘dissolution-recrystallization’ method of embedding high loading and uniform Ni NPs into the shell of hollow silicalite-1 (S-1) zeolite. The sizes of Ni NPs maintained at ca. 4–5 nm with increasing Ni loading from 3% to 20%, and the TOF kept at ca. 60 s−1 (800 °C) in the dry reforming of methane reaction. The augmented density of active sites with Ni loading rendered an outstanding reaction rate of 20.0 molCH4/gcat/h over 20% Ni@S-1. The embedded structure also endowed a good stability upon running for 150 h. This study paves the way for embedding high loading and uniform metal nanoparticles inside the zeolite, providing an effective strategy to stabilize metals under harsh reaction conditions.

Mechanochemical Synthesis of Ni–Y/CeO2 Catalyst for Nonthermal Plasma Catalytic CO2 Methanation

Nonthermal plasma (NTP)-assisted CO2 methanation can activate and convert stable CO2 molecules under ambient conditions as compared to conventional thermal catalysis (normal operation temperature up to 450 °C), which is a good technique to reduce CO2 emissions and simultaneously utilize the renewable energies like solar and wind. It is critical to develop a robust catalyst with good catalytic performance in order to make NTP catalytic CO2 methanation more competitive. Herein, we present a simple yet efficient synthesis of CeO2-supported Ni catalysts with yttrium (Y) as the promoter (i.e., Ni–Y/CeO2) via mechanochemical synthesis for efficient NTP catalytic CO2 methanation. The developed 7.5Ni–1Y/CeO2 catalyst demonstrated the highest energy efficiency values for CO2 conversion and CH4 yield, i.e., ∼57 gCO2 kWh–1 and ∼17 gCH4 kWh–1, respectively. The CO2-TPD and HRTEM results confirmed that the doped Y positively enhanced the basicity of the catalysts and also decreased the particle size of Ni nanoparticles, thus promoting the NTP catalytic activity of CO2 methanation. The catalyst displayed excellent short-term stability for plasma catalytic CO2 methanation over a 12 h on-stream evaluation, showing a CO2 conversion of 84.2 ± 1.8% and a CH4 selectivity of 83.3 ± 1.9%.

Effect of Nickel Precursor on the Catalytic Performance of Graphene Aerogel‐Supported Nickel Nanoparticles for the Production of COx‐free Hydrogen by Ammonia Decomposition

Graphene aerogel (GA), a promising porous material with high specific surface area and electrical conductivity, is utilized to disperse nickel nanoparticles to reach high catalytic activity in COx‐free hydrogen production from ammonia. Ni(NO3)2·6H2O and Ni (II) acetylacetonate (Ni(acac)2) were considered as metal precursors and the pH of the impregnation solution was varied to investigate the effects on the catalytic properties of the GA‐supported nickel catalysts. Data showed that the best dispersion and homogeneity, as well as the catalytic performance, is achieved with Ni(acac)2. An average Ni nanoparticle size of 13.6 ± 4.3 nm was obtained on the GA‐supported catalyst prepared by using Ni(acac)2 dissolved in an impregnation solution with a pH of 10.2. This catalyst with a Ni loading of 11.1 wt% provided an ammonia conversion of 70.2% at a space velocity of 30 000 mL NH3 gcat−1 h−1 and 600 °C corresponding to a hydrogen production rate of 21.5 mmol H2 gcat−1 min−1. Data illustrated that the difference between the point of zero charge of the support and the pH of the impregnation solution set by the type of the Ni precursor is a major parameter controlling the metal dispersion and the consequent catalytic activity.

Enhanced dispersion of nickel nanoparticles on SAPO-5 for boosting hydroisomerization of n-hexane

The nickel based bifunctional catalyst with enhanced hydroisomerization performance was developed using an in-situ solid synthesis method. It was achieved to stabilize smaller Ni active sites on SAPO-5 using ethylenediaminetetraacetic acid (EDTA) ligands. The role of EDTA ligands was clarified by controlling the molar ratio of EDTA to Ni2+ (EDTA/Ni2+) over Ni/SAPO-5 catalysts. EDTA ligands inhibited the formation of nickel aluminate spinel and aggregation of NiO species during calcination, which dispersed Ni nanoparticles in a mean size of 4.7 nm on SAPO-5. The size of Ni nanoparticles could be controlled by regulating EDTA/Ni2+ ratio in [Ni-EDTA]2- complex. The prepared catalyst exhibited high yield of isomers (54.0%) and di-branched isomers selectivity (18.0%) in the n-hexane hydroisomerization, which was approximately 2 times higher than that of the Ni/SAPO-5 catalyst without EDTA ligands at similar conversion. These results are important to propose a facile approach for the preparation of highly dispersed non-noble metal based bifunctional catalysts at a high loading.

Decoupling the size and support/metal loadings effect of Ni/SiO2 catalysts for CO2 methanation

CO2 methanation constitutes one of the most promising technologies for highly efficient CO2 utilization while reducing the emission of greenhouse gases. The active Ni-based catalysts show the size-dependent activity for this reaction; however, the Ni size effect was highly coupled with the effect of support or metal loadings. Herein, the effect of nickel particle size in the range of 3.5–7.5 nm on CO2 methanation has been investigated using constant Ni loading of 2 wt.% Ni/SiO2 catalysts based on inert silica support prepared by different methods. The catalyst with small Ni nanoparticle exhibited highly enhanced catalytic performance, illustrating that the performance of CO2 methanation can be improved by tuning the particle size of Ni supported on SiO2. In situ diffuse reflectance Fourier transform infrared spectroscopy (DRIFTS) results indicated that small Ni particle size is beneficial to the formation of initial monodentate carbonate and important intermediates such as monodentate formate and linearly adsorbed CO species which are highly in favor of CO2 methanation reaction. This work provides valuable guidelines for designing an effective CO2 methanation catalyst by tuning the size of Ni nanoparticles.

Trifunctional strategy for the design and synthesis of a Ni-CeO2@SiO2 catalyst with remarkable low-temperature sintering and coking resistance for methane dry reforming

In this study, a trifunctional strategy was developed to prepare a confined Ni-based catalyst (Ni-CeO2@SiO2) for dry reforming of methane (DRM) of two main greenhouse gases—CO2 and CH4. The Ni-CeO2@SiO2 catalyst was fabricated by utilizing the confinement effect of the SiO2 shell and the synergistic interaction between Ni-Ce and the decoking effect of CeO2. The catalysts were systematically characterized via X-ray diffraction, N2 adsorption/desorption, transmission electron microscopy, energy dispersive X-ray spectroscopy, hydrogen temperature reduction and desorption set by program, oxygen temperature program desorption, Raman spectroscopy, thermogravimetric analysis, and in situ diffuse reflectance infrared Fourier transform spectroscopy measurements to reveal their physicochemical properties and reaction mechanism. The Ni-CeO2@SiO2 catalyst exhibited higher activity and stability than the catalyst synthesized via the traditional impregnation method. In addition, no carbon deposition was detected over Ni-CeO2@SiO2 after a 100 h durability test at 800 °C, and the average particle size of Ni nanoparticles (NPs) in the catalyst increased from 5.01 to 5.77 nm. Remarkably, Ni-CeO2@SiO2 also exhibited superior low-temperature stability; no coke deposition was observed when the catalyst was reacted at 600 °C for 20 h. The high coking and sintering resistance of this confined Ni-based DRM catalyst can be attributed to its trifunctional effect. The trifunctional strategy developed in this study could be used as a guideline to design other high-performance catalysts for CO2 and CH4 dry forming and accelerate their industrialization.

Promotional Effect of Ni−Sn Interaction over Ni Supported on Sn‐incorporated MCM‐41 Catalysts for CO2 Reforming of CH4

AbstractSintering of active Ni sites and deposition of coke remain challenging issues for catalytic dry reforming of methane. Herein, Ni supported on the Sn‐incorporated MCM‐41 catalysts were synthesized and tested for DRM process. The structural and physicochemical properties of fresh and spent samples were studied by N2 adsorption‐desorption, XRD, H2‐TPR, XPS, TEM, STEM‐EDS, Raman, and TGA techniques. It was revealed that Sn addition improved the dispersion and decreased the size of active Ni nanoparticles by tuning the charger transfer between Ni and Sn. The formation of Ni−SnOx interface provides more possibilities to activate CO2. The best results were obtained by 2Ni/Sn−MCM‐41 sample with the Ni/Sn mole ratio of 2 : 1, contributing CH4 conversion of 95% and CO2 conversion of 94% at 800 °C. Moreover, the presence of Sn increased the resistance to sintering of Ni‐based catalysts during the severe conditions, thereby the Ni nanoparticle size only appeared a slight growth after 32 h TOS. Combined with the characterization of the spent 2Ni/Sn−MCM‐41 sample, it was revealed that the coke deposition of the deactivated catalyst was dominated by amorphous carbon, which could be responsible for the desirable regeneration ability of the catalyst.

Preparation and characterization of magnetic nickel nanoparticles by chemical reduction reaction

The efficiency of many of conversion-processes in petroleum and industrial improves upon application of materials with the nanosized scale dimension, which is caused by enhancements and advances of improved properties as the particle size decreases. Nickel nanoparticles has numerous applications in petroleum industry with its own catalytic in additional to the magnetic properties. In this study, high purity nanosized magnetic nickel particles has been effectively prepared by chemical reduction of nickel chloride using hydrazine hydrate as reducing agent in aqueous solutions containing ethylene glycol and water and using polyvinylpyrrolidone (PVP) as anti-agglomeration agent. Nanosized Ni particles samples with different hydrazine to nickel chloride mole ratios and PVP to nickel chloride ratios were obtained at constant temperature of 80 °C.
 The morphology and structural properties of the produced magnetic nickel nanoparticles were characterized by powder XRD and AFM methods. XRD study revealed that the prepared nanoparticles were pure nickel nanoparticles without considerable oxides or other impurity phases. AFM test revealed that all prepared Ni nanoparticles was in nano scale, it was stated that Ni nanoparticles size was very affected by the hydrazine/nickel mole ratio. Experimental results showed that particle size decreases from 94.35 nm to 71.48 nm when increases the [N2H4]/[Ni2+] molar ratio from 15:1 to 45:1.

Structural and magnetic properties of size-controlled Fe–Ni nanoparticles synthesized by diffusing Fe atoms into preformed Ni nanoparticles

Fe–Ni nanoparticles are attractive candidates for magnetic cores of transformers and inductors that are operated at high frequencies. When applying Fe–Ni nanoparticles in magnetic cores, particle size must be controlled to enhance magnetic properties. A two-step synthetic method can be useful for fabricating size-controlled Fe–Ni nanoparticles. In the first step, Ni nanoparticles are synthesized by reducing Ni (II) acetylacetonate in oleylamine (OA) with trioctylphosphine (TOP). Thereafter, Fe (III) acetylacetonate is reduced and Fe atoms diffuse into the preformed Ni nanoparticles in OA. The size of the Fe–Ni nanoparticles depends on that of the Ni nanoparticles. However, no studies have conducted extensive investigations of their synthesis and magnetic properties with various particle sizes. Here, we attempted particle-size-controlled synthesis of Fe–Ni nanoparticles and investigated their magnetic properties. The particle size of the Fe–Ni nanoparticles was varied between 13.1. and 20.5 nm by varying the size of Ni nanoparticles. The saturation magnetization (Ms) gradually reduced with the decrease in particle size because of the increased amount of oxidized surface atoms and phosphides. Coercive forces (Hc) also decreased as the particle size decreased to 15 nm because of the increased effect of superparamagnetism, while the Hc greatly increased with the particle size reduction below 14 nm because of the ferromagnetism exhibited by the Fe layer owing to undiffused Fe atoms. Thus, using this synthetic method, Fe–Ni nanoparticles with a size of approximately 15 nm can be produced, which have a minimum Hc and are the most appropriate for magnetic cores.

A Simple Model for Gas-Phase Synthesis of Nickel Nanoparticles

Gas-phase synthesis of nickel (Ni) nanoparticles by thermal decomposition of nickel tetracarbonyl, Ni(CO)4, is simulated accounting for nucleation, surface growth, coagulation, and sintering. By detailed analysis of phenomenological expressions for sintering, it is shown that surface diffusion (SD) is the dominant sintering mechanism for Ni nanoparticles at low temperatures (T < 700 K) and early stages of sintering, but grain boundary diffusion (GBD) dominates as sintering progresses and at higher temperatures. This is consistent with molecular dynamics simulations of noble metal nanoparticle sintering. Using the average of the above SD and GBD characteristic sintering times for Ni as well as a monodisperse population balance model (MPBM) that accounts for agglomerate morphology, polydispersity, and evolving structure with scaling laws from mesoscale simulations, Ni agglomerate sintering is benchmarked with measurements of agglomerate mobility and primary particle diameters. The MPBM predictions are in good agreement with the measured concentration and sizes of Ni nanoparticles by thermal decomposition of Ni(CO)4 in a hot wall flow reactor.

Multi-dimensional ordered mesoporous carbon/silica@Ni composite with hierarchical nanostructure for strong and broadband microwave absorption

Ordered mesoporous carbon (OMC) has been regarded as a promising carbonaceous material for microwave absorption (MA) owing to its high specific surface area, sufficient ordered mesoporous nanostructures and easy decoration. However, its development in MA performance is seriously hampered by its shortcomings of lacking magnetic loss and poor impedance matching. Herein, a series of multi-dimensional ternary OMC/SiO2@Ni composites with hierarchical nanostructure (zero-dimensional (0D) Ni nanoparticles and three-dimensional (3D) OMC/SiO2 framework) is successfully prepared via a self-assembly method, an in situ synthesis, and followed by a calcination treatment. By adjusting the calcination temperature and Ni nanoparticle content, OMC/SiO2@Ni composites with different graphitization degree, Ni nanoparticle size and magnetic properties can be easily obtained. Remarkably, OMC/SiO2@Ni0.5-700 composite exhibits an exceedingly strong reflection loss (RL) value of −62.2 dB and a broad effective absorption bandwidth (RL ≤ −10 dB) of 8 GHz (almost covers X and Ku bands) with a layer thickness of only 2.5 mm. Such fabulous MA performance comes from a synergy between the well-designed hierarchical ternary nanostructure and improved impedance matching. This work provides an insight for rational structure design and multi-component loss mechanism of lightweight MA material, which shows great potential in practical applications.

Decoupling the effect of Ni particle size and surface oxygen deficiencies in CO2 methanation over ceria supported Ni

The study describes decoupling the effect of surface oxygen vacancies and Ni particle size in the CO2 methanation over CeO2 supported Ni nanoparticles. The availability of surface oxygen vacancies with the interaction between Ni and CeO2 served to appreciably enhance the catalytic capacity for activation of CO2, generating higher conversion rates, larger selectivity to CH4 and lower activation energies relative to Ni/SiO2. A structure-sensitivity in the reaction over Ni/CeO2 was established without the interference of different concentrations of surface oxygen vacancies, where the turnover frequencies of CO2 decreased with increasing the Ni nanoparticle sizes (8−21 nm). The TPSR and Operando FT-IR analysis demonstrated that formate was the critical intermediate for CH4 formation. The CO formation with smaller nickel size resulted from the carboxyl species. In addition, the long-term evaluations and TGA measurements revealed small Ni nanoparticles suffered a temporary loss of activity due to the carbon deposition.

Boosting hydrogen production from steam reforming of ethanol on nickel by lanthanum doped ceria

Stable and efficient hydrogen production has always been the focus of industry, and steam reforming of ethanol (SRE) is one of the most robust, renewable and cheap technologies. To develop excellent SRE catalysts highly resisting coke formation and metal sintering, La, Tb, and Zr have been doped as a third metal into Ni-CeO2 catalyst using a sol-gel method. The size and dispersion of Ni nanoparticles, surface oxygen vacancies and metal-supported interaction have been finely tuned, with which the catalytic performance is closely associated. La-doped ceria supported Ni (Ni-CeLa0.20) exhibited superior catalytic performance, which is ascribed to its large Ni active surface area, abundant oxygen vacancies and suitable metal-supported interaction. DFT calculations showed that the doping of La into Ni-CeO2 can promote the generation of oxygen vacancies and facilitate the dissociation of water. On Ni-CeLa0.20, complete conversion of ethanol and stable hydrogen production have been maintained in the 3000-min test. The coke deposition is only 0.48 mgc/gcat h at 600 °C under the GHSV of 55920 mL/gcat∙h.