Ni CeO2 Research Articles

Ni-CeO2 Heterostructures in Li-S Batteries: A Balancing Act between Adsorption and Catalytic Conversion of Polysulfide.

Lithium–sulfur (Li–S) batteries have attracted considerable attention over the last two decades because of a high energy density and low cost. However, the wide application of Li–S batteries has been severely impeded due to the poor electrical conductivity of S, shuttling effect of soluble lithium polysulfides (LiPSs), and sluggish redox kinetics of S species, especially under high S loading. To address all these issues, a Ni–CeO2 heterostructure‐doped carbon nanofiber (Ni‐CeO2‐CNF) is developed as an S host that combines the strong adsorption with the high catalytic activity and the good electrical conductivity, where the LiPSs anchored on the heterostructure surface can directly gain electrons from the current collector and realize a fast conversion between S8 and Li2S. Therefore, Li–S batteries with S@Ni‐CeO2‐CNF cathodes exhibit superior long‐term cycling stability, with a capacity decay of 0.046% per cycle over 1000 cycles, even at 2 C. Noteworthy, under a sulfur loading up to 6 mg cm−2, a high reversible areal capacity of 5.3 mAh cm−2 can be achieved after 50 cycles at 0.1 C. The heterostructure‐modified S cathode effectively reconciles the thermodynamic and kinetic characteristics of LiPSs for adsorption and conversion, furthering the development of high‐performance Li–S batteries.

Methane dry reforming with CO2 over ceria supported Ni catalyst prepared by reverse microemulsion synthesis

Reverse microemulsion synthesis route was employed for the preparation of Ni/CeO2 catalysts with the aim of their application in dry reforming of methane. The catalytic activity and stability of the prepared catalysts was investigated in the temperature range of 550–800 °C with the ratio of CH4/CO2 = 1 and at high gas hourly space velocity (GHSV) of reactants (1.2 × 105 ml h−1 g−1). In the prepared series of catalysts (20% Ni/CeO2, 40% Ni/CeO2, 80%Ni/CeO2); 40% Ni/CeO2 (NC2) exhibited higher catalytic activity and better stability compared to 20% Ni/CeO2 (NC1) and 80% Ni/CeO2 (NC3). Moreover, results indicated that NC2 was found to be stable catalyst for both gas yield and H2/CO ratio. This study indicated that proper balance between Ni metal and CeO2 content played a critical role in the achievement of better catalyst performance and in the decrease of carbon deposition. The characterization of fresh and spent catalysts was done by BET, XRD, TPR-H2, EDX and TEM.

Band gap tuning by Gd and Fe doping of LaNiO3 to boost solar light harvesting for photocatalytic application: A mechanistic approach

Gadolinium and iron doped LaNiO3 perovskites were prepared via facile micro-emulsion approach and characterized using various techniques. A single-phase distorted rhombohedral geometry was obtained with effective doping of Gd and Fe ions in LaNiO3. Photoluminescence spectra show the decrease in intensities on Gd and Fe doping. The energy band gap values decreased from 2.85 to 2.21 eV by doping. The photocatalytic activity (PCA) of undoped and doped LaNiO3 was evaluated by the degradation of RhB under sunlight irradiation. Gd and Fe doped NPs shows about 89.3% degradation of RhB with 90 min versus 33.5% for LaNiO3. The antibacterial activity of the undoped LaNiO3 and Gd and Fe doped NPs were examined against Bacillus cereus (B, cereus), Escherichia coli (E. coli) Staphylococcus aureus (S. aureus) and Bacillus subtilis (B. subtilis), which shows remarkable antibacterial activities. The antifungal activity was improved by doping against Green fumigates, penicillin and Black niger. Molecular docking studies were performed with ligand (La–Gd Ni–CeO) and GerK3, GerBC and FtsZ receptor protein of B. megaterium and B. subtilis exhibited a reliable binding affinity towards microbial proteins. Results reveals that the Gd and Fe doped material annealed at 950 °C have narrow band gap and revealed a probable catalytic application under visible light exposure.

火炎噴霧熱分解法により合成した多孔質ナノNiOを用いた80 wt% Ni–CeO<sub>2</sub>触媒の調製とそのCO<sub>2</sub>メタン化反応活性

火炎噴霧熱分解法により合成した多孔質ナノNiOを用いた80 wt% Ni–CeO<sub>2</sub>触媒の調製とそのCO<sub>2</sub>メタン化反応活性

Confining Ni and ceria in silica shell as synergistic multifunctional catalyst for methane dry reforming reaction

Ni catalysts are the most investigated for methane dry reforming reaction, but sintering of Ni nanoparticles and deposition of carbon are great challenges for performance stability. To overcome the obstacles, synergistic multifunctional (Ni/CeO2)@SiO2 catalyst by confining Ni nanoparticles and CeO2 nanocrystals in SiO2 nanospheres is synthesized in this work. The core construction promotes reaction activity and reduces carbon deposition, and the shell confines migration of the core components to maintain their sizes. The functions contribute to the enhanced performance of methane dry reforming reaction. High resolution Transmission electron microscopy, X-ray power diffraction, Hydrogen temperature programmed reduction etc. suggest that the great enhancements are due to the synergetic multifunction of the size effect and the strong metal-support interaction from Ni and CeO2, and the confinement effect from SiO2 in the catalyst. This finding about the synergetic strategy provides an efficient way to completely resolve Ni sintering and carbon formation in methane dry reforming, and is highly applicable to other reactions that suffering sintering and carbon deposition.

Effect of Current Density on the Properties of Ni–CeO2 Composite Coatings prepared using Magnetic Field-Assisted Jet Electrodeposition

Effect of Current Density on the Properties of Ni–CeO2 Composite Coatings prepared using Magnetic Field-Assisted Jet Electrodeposition

Mechanistic understanding of CO2 hydrogenation to methane over Ni/CeO2 catalyst

Ni/CeO2 is considered as a potentially efficient catalyst for CO2 methanation. Herein, all possible reaction pathways of CO2 methanation were investigated by the first-principles calculations based on density functional theory to uncover the intrinsic reaction mechanism over Ni/CeO2 catalyst. Theoretical analysis results indicate that the strong metal-support interaction between Ni nanoparticle and CeO2 support is closely associated with the transfer and accumulation of electrons towards the interface. Ni nanocluster on Ni/CeO2 catalyst is the most active adsorption and activation site of CO2 molecule. CO2 methanation over Ni/CeO2 catalyst is mainly governed by the RWGS + CO-hydro pathway, rather than the pathways of formate formation and direct CO bond cleavage. The main reaction channel of CO2 methanation is CO2* → HOCO* → CO* → HCO* → H2CO* → CH2* → CH3* → CH4*. H-assisted CO bond breakage of H2CO* plays a critical role in CO2 methanation, and is the rate-limiting step of RWGS + CO-hydro pathway. The optimal pathway and rate-limiting step of CO2 methanation are altered in the presence of CeO2. A complete reaction network is proposed for further understanding the molecular-level reduction mechanism of CO2 hydrogenation to methane on Ni/CeO2 catalyst.

Mechanistic investigation of aluminide coating formation by low-pressure chemical vapor deposition method on NiCoCrAlY coating in presence of nickel-ceria composite layer

In this study, a hybrid coating comprised of NiCoCrAlY fabricated by HVOF method, Ni–CeO2 composite coated by electrodeposition, and aluminide coating applied by low pressure chemical vapor deposition (LPCVD) method are investigated. To elucidate the formation process of aluminide coating, the microstructure and properties of the applied coatings were examined by field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), and EDS analyses. It was concluded that the desired β-NiAl phases are uniformly created within a single step on the surface. Furthermore, with the extending of the coating duration from 2 to 4 h, the thickness of the aluminide coating was increased from 14 to 25 μm. The thickness values were increased even further in the presence of Ni–CeO2 coating, where the growth mechanism was also changed. Within 4 h, a coating with a thickness of roughly 50 μm was obtained. Moreover, in the presence of Ni–CeO2 coating, it was observed that the inward diffusion of aluminum was predominant at the beginning of the process, whereas with longer processing durations, the outward diffusion of the nickel becomes dominant instead.

Ni nanoparticles dispersed on oxygen vacancies-rich CeO2 nanoplates for enhanced low-temperature CO2 methanation performance

• A CeO 2 -P carrier rich in oxygen vacancies was synthesized for Ni-based catalyst. • High low-temperature CO 2 methanation activity and excellent stability were achieved. • The role of oxygen vacancies in enhancing CO 2 methanation performance was revealed. Developing efficient catalysts with superior low-temperature catalytic performance is highly promising yet challenging for CO 2 methanation. Here we synthesized a nanoplate-shaped CeO 2 , which was rich in oxygen vacancies, as the carrier to disperse the nickel nanoparticles. The resultant catalyst (Ni/CeO 2 -P) showed remarkable low-temperature CO 2 methanation performance with a CO 2 conversion of high than 84% and 100% CH 4 selectivity at a low temperature of 300 °C. A 100 h-on-stream test at 300 °C demonstrated the excellent stability of Ni/CeO 2 -P. Even when the WHSV rose as high as 30000 mL g −1 h −1 , the Ni/CeO 2 -P catalyst still possessed a maximum CO 2 conversion of approximately 79%. The surface characterization demonstrated that the abundant oxygen vacancies on the CeO 2 nanoplates led to more amounts of NiO-CeO 2 structures formed, which resulted in a stronger interaction between Ni metal and CeO 2 support. This stronger NiO-CeO 2 interaction was proved extraordinary in promoting the reaction performance as compared with metallic Ni. Also, by the in-situ DRIFTS technology, the reaction intermediates and possible reaction pathway were raised for CO 2 methanation.

Ru–CeO2 and Ni–CeO2 Coated on Open-Cell Metallic Foams by Electrodeposition for the CO2 Methanation

CO2 methanation structured catalysts, made by a layer of Ru–CeO2 or Ni–CeO2 (Ru/Ce = 3/97; Ni/Ce = 1/3 and 3/1) on open-cell NiCrAl foams, are prepared by electrodeposition and a subsequent calcina...

Catalytic ammonia decomposition over Ni-Ru supported on CeO2 for hydrogen production: Effect of metal loading and kinetic analysis

Ceria-supported Ni-Ru bimetallic catalysts with different metal loadings have been prepared by co-impregnation, characterized and tested in the production of hydrogen from the catalytic decomposition of ammonia. The bimetallic catalysts showed an excellent catalytic performance in long-term stability tests with respect to monometallic Ru/CeO2 and Ni/CeO2 and in multicycle tests under pure ammonia. The best catalytic performance has been obtained over catalysts with 2.4−5 wt.% Ni, 0.4−0.6 wt.% Ru, and a Ni/Ru wt.% ratio of ca. 7. TOFH2 values exceeding 2 s−1 have been obtained, which are among the highest reported for ammonia decomposition at 400 °C. Raman spectroscopy, XRD, HRTEM, XPS, TPR and H2 chemisorption have revealed the existence of an intimate contact between Ni and Ru and CeO2, which is considered the reason of the excellent catalytic activity and stability observed. A kinetic model has been developed using the Langmuir-Hinshelwood-Hougen-Watson approach for the decomposition of ammonia in a fixed bed reactor. The reaction rate expression of the ammonia decomposition on Ni-Ru bimetallics supported on ceria suggests that the dehydrogenation of the ammonia adsorbed on the surface of the catalyst is the limiting step of the reaction and that ammonia decomposition is inhibited by the presence of H2.

CeO2-Promoted Ni/SiO2 Catalysts for Carbon Dioxide Reforming of Methane: The Effect of Introduction Methodologies

Three typical methods, subsequent coating, co-impregnation and sequential impregnation, were employed to investigate the effect of introduction methodologies for CeO2-promoted Ni/SiO2 catalysts. The CeO2@Ni/SiO2 catalyst prepared with the subsequent coating method was found to exhibit the best initial activity and superior long-term stability in CO2 reforming of methane. Comparative characterizations documented that small Ni size and intimate Ni–CeO2 contact were generated on the CeO2@Ni/SiO2 catalyst, leading to excellent reforming activity. In addition, pronounced redox property and strong surface basicity were created on the CeO2@Ni/SiO2 catalyst, resulting in exceptional coke resistance and thus superior long-term stability. This work unravels the impact of various introduction methods on the catalyst structure, which would help design robust nanocomposite catalysts with outstanding catalytic performance.

Selective hydrogenolysis of aryl ethers over a nitrogen-doped porous carbon supported Ni–CeO2 catalyst at low temperature

The selective depolymerization of lignin into aromatics is a sustainable way to improve the economics of the overall biorefinery process.

Role of CeO2/ZrO2 mole ratio and nickel loading for steam reforming of n-butanol using Ni–CeO2–ZrO2–SiO2 composite catalysts: A reaction mechanism

This study presents steam reforming of n-butanol to synthesis gas using high surface area mesoporous Ni–CeO2–ZrO2–SiO2 composite catalysts. The reaction proceeds through a combination of dehydrogenation, dehydration, and cracking reactions with propanal, butanal, and C2–C4 hydrocarbons as intermediate compounds. The ceria forms a solid solution with zirconia, promotes dispersion of nickel, and enhances oxygen storage/release capacity. The carbon conversion to synthesis gas (CCSG) and hydrogen yield are thus enhanced with increasing CeO2/ZrO2 mole ratio up to 1:2 and decreased slightly for higher mole ratios. The CCSG and hydrogen yield are also boosted by increasing the amount of nickel in the catalyst up to 20 wt%. 1:2 CeO2/ZrO2 mole ratio and 20 wt% nickel content are thus deliberated as optimum. The optimum catalyst exhibits stable catalytic performance for about 30 h time-on-stream. The study further presents the effect of temperature and steam/carbon mole ratio on n-butanol steam reforming.

Electrochemical hydrogen storage behavior of Ni-Ceria impregnated carbon micro-nanofibers

A hierarchical porous structured carbon micro-nanofiber containing the bimetallic configuration of the nickel (Ni) and ceria (CeO2) nanoparticles (NPs) was synthesized and tested for the electrochemical hydrogen (H2) storage capacity. The electrode exhibited a high H2 storage capacity of 498 mA h/g or 1.858% (w/w) at the charge-discharge current density of 500 mA/g. A mechanistic insight showcased the combined contributions of the high surface area containing activated carbon microfiber (ACF) substrate, the graphitic carbon nanofibers (CNFs), and the Ni and CeO2 NPs, towards the augmented electrochemical H2 storage capacity and cyclic stability of the fabricated Ni–CeO2–CNF/ACF electrode. Ni served as the catalyst for growing the CNFs via chemical vapor deposition as well as for storing H2 via spillover mechanism, while CeO2 created the charge carrier vacancies in the material. The measured cycle retention capacity of 99% and charge-discharge efficiency of 97.6% confirm the electrochemically stable characteristics of Ni–CeO2–CNF/ACF, and clearly indicate it to be an economically viable and efficient H2-storage material.

Nickel-Ceria Nanowires Embedded in Microporous Silica: Controllable Synthesis, Formation Mechanism, and Catalytic Applications.

Designing highly efficient catalysts for use in fuel production is a highly attractive research area but still remains challenging. Herein, for the first time, ultrafine Ni nanoparticles (NPs) self-assembled on ceria nanowires (NWs) and then embedded in a microporous silica shell (denoted as Ni-CeO2@SiO2) are successfully designed and synthesized via a one-pot facile strategy. The average diameter of Ni-CeO2 NWs is just 2.9 nm, and the length is up to 102.7 nm. The resulting Ni-CeO2@SiO2 exhibits high performance and 100% hydrogen selectivity for H2 production from N2H4 and N2H4BH3 in aqueous solution. Unexpectedly, Ni-CeO2@SiO2 also has good catalytic performance and thermal stability for CO2 methanation. The high catalytic performance of Ni-CeO2@SiO2 can be attributed to the synergistic electronic effect and strong interaction between Ni NPs and CeO2 NWs with plenty of oxygen vacancies, as well as the unique structure effect. As an effective strategy, the present work provides an opportunity to embed ultrafine metal NPs-CeO2 NWs into a microporous silica shell, which has broad application prospects in various catalytic fields.

Low temperature formation of aluminide coatings on the electrodeposited nanocrystalline Ni and its oxidation resistance with La2O3/CeO2 nanoparticle dispersion

A systematic study was made to determine the effects of aluminizing temperature and time on the growth of the Ni2Al3 coating on the electrodeposited nanocrystalline (NC) Ni with and without La2O3/CeO2 nanoparticles by the pack aluminizing process at 550 °C/600 °C. The results show that the growth of Ni2Al3 coating obeyed the parabolic law after a delay time (t0), which decreased with increment of aluminizing temperature. The addition of La2O3/CeO2 nanoparticles significantly refined the grain of aluminide. The La2O3/CeO2-dispersed Ni2Al3 coatings exhibit a lower oxidation rate than the La2O3/CeO2-free one in air at 900 °C, because of various effects of La2O3/CeO2 on the oxidation including the grain refinement effect of the aluminide, the “reactive element effect” (REE) and the epitaxial template effect of La2O3 to promote the growth of α-Al2O3. Furthermore, the accumulation of La2O3 particles at the degradation front slightly inhibited the interdiffusion between the aluminide and Ni; while the formation of a CeO2-rich layer between aluminide and Ni–CeO2 film significantly mitigated the degradation of aluminide coatings.

Hydrogen Production via Low-Temperature Steam–Methane Reforming Using Ni–CeO2–Al2O3 Hybrid Nanoparticle Clusters as Catalysts

The hybrid nanostructures, Ni-only and Ni–CeO2 nanoparticles decorated on Al2O3 nanoparticle clusters (Ni–Al2O3 NPC and Ni–CeO2–Al2O3 NPC, respectively), were successfully synthesized as catalysts ...

Microstructure Analysis of the Pack Cementation Aluminide Coatings Modified by CeO2 Addition

Minor additions of reactive elements (Y, Ce, Hf, etc.) can improve the oxidation behavior of high temperature alloys and coatings such as aluminide coatings. In the current investigation cerium-modified aluminide coatings were developed via additions of CeO2 to the powder mixture of high activity pack cementation aluminizing. Nickel-based substrates were aluminized at 750 °C and then diffusion annealed at 1080 °C. Microstructure of the coatings was studied using scanning electron microscopy, energy dispersive spectroscopy and X-ray diffraction. The results were compared with the characterization results of specimens achieved by aluminizing an electrodeposited Ni–CeO2 interlayer at 1030 °C. The coatings modified by CeO2 addition to the pack showed a dense Al-rich NiAl surface layer with cerium distributed in the coating, however, the coatings modified by Ni–CeO2 interlayer revealed a porous Ni-rich aluminide layer containing CeO2 particles. Increasing the CeO2 content of the pack decreased the thickness of the final coating, but the presence of CeO2 particles in the interlayer increased the thickness of the final aluminide coating. The observed microstructural features were explained using thermodynamic analysis of equilibrium concentration of the involved gaseous species.

Highly efficient and stable Ni/CeO2-SiO2 catalyst for dry reforming of methane: Effect of interfacial structure of Ni/CeO2 on SiO2

Manipulating interfacial structure and interaction between metal and supports is important for many heterogenous catalysts with the aim at achieving high and stable activity and selectivity. In this work, two kinds of Ni/CeO2-SiO2 catalysts are fabricated and designed, including CeO2 close contact with Ni nanoparticles (Ni/CeO2-SiO2-P) or CeO2 away from Ni nanoparticles (Ni/CeO2-SiO2-C) for dry reforming of methane. Ni/CeO2-SiO2-P exhibits superior low-temperature activity and H2/CO ratio compared with Ni/CeO2-SiO2-C. CO2 and CH4 conversions on the former (87.3% and 78.5%) are higher than those of the later (80.5% and 67.8%) at 700 °C. Meanwhile, Ni/CeO2-SiO2-P is stable in the long-term study whereas Ni/CeO2-SiO2-C presents poor stability and the activity dramatically decreases in 10 h. The improved performance and stability on Ni/CeO2-SiO2-P originates from more reactive oxygen species and more accessible sites for the formate species on the metal–support interface. The reaction order and activation energy of both catalysts are also calculated in the kinetic studies. This work opens up new possibilities for exploring the effect of metal–support on designing highly efficient heterogeneous catalysts.