Ni Counterparts Research Articles

Amorphization-sparked superb activity and excellent coke-resistance of Ni nanocatalyst

Selective conversion of CH4 and CO2 to syngas via the dry reforming reaction is highly desirable in terms of restraining the greenhouse effect and meanwhile acquiring useful chemicals. However, the most promising Ni catalysts for the reaction still suffer from severe coking and thus poor durability. Here, we report that using amorphous Ni nanoparticles synthesized on an N modified mesoporous silica support, the catalytic activity and coke-resistant performance of Ni toward the photothermal dry reforming of methane (DRM) are greatly improved. Theoretical calculations further unveil that the amorphous Ni nanoparticles are much more energetically favorable to activate the CH4 and CO2 molecules as well as to remove the C* intermediates for coke formation than their crystalline Ni counterparts, which renders the amorphous Ni nanoparticles with both superb activity and excellent coke-resisting property. This finding possibly provides a new avenue to make both highly efficient and anti-coking catalysts for the DRM reaction and beyond via facile amorphization of active metals.

Highly selective urea electrooxidation coupled with efficient hydrogen evolution

Electrochemical urea oxidation offers a sustainable avenue for H2 production and wastewater denitrification within the water-energy nexus; however, its wide application is limited by detrimental cyanate or nitrite production instead of innocuous N2. Herein we demonstrate that atomically isolated asymmetric Ni–O–Ti sites on Ti foam anode achieve a N2 selectivity of 99%, surpassing the connected symmetric Ni–O–Ni counterparts in documented Ni-based electrocatalysts with N2 selectivity below 55%, and also deliver a H2 evolution rate of 22.0 mL h–1 when coupled to a Pt counter cathode under 213 mA cm–2 at 1.40 VRHE. These asymmetric sites, featuring oxygenophilic Ti adjacent to Ni, favor interaction with the carbonyl over amino groups in urea, thus preventing premature resonant C⎓N bond breakage before intramolecular N–N coupling towards N2 evolution. A prototype device powered by a commercial Si photovoltaic cell is further developed for solar-powered on-site urine processing and decentralized H2 production.

In-situ construction of amorphous–crystalline NiCo bimetallic oxyhydroxide for low-temperature supercapacitor device

As rechargeable energy storage device, supercapacitor (SC) cell is facing a new challenge for low-temperature application since the low-temperature environment seriously suppresses the reaction kinetics of the electrode materials. In this work, NiCo bimetallic oxyhydroxides (NixCoyOOH, Ni/Co = x/y) composed of amorphous-crystal structure were in-situ synthesized using electrodeposition, which are capable of operating at temperatures as low as − 4 °C, totally different from the pure Ni or Co oxyhydroxides counterparts. The microstructures of the NixCoyOOH were characterized by XRD, SEM, TEM, and XPS, finding an obviously transit from microparticles (NiOOH) and porous arrays (CoOOH) to flower-like nanospheres and a complicated amorphous-nanocrystalline structure. Electrochemical tests show that the Ni2Co1OOH cathode presents a super-high specific capacitance of 3720 and 2311F g−1 at low and high charging current densities of 1 and 20 A/g at 23 ℃ in aqueous electrolyte, respectively. The assembled device of Ni2Co1OOH//activated carbon (AC) delivers a high energy density of 22.8 Wh kg−1 at 7466 W kg−1 in polyvinyl alcohol (PVA)-KOH hydrogel at 0 ℃, and offers anexceptionalstability of 92.5 % of capacity after 8000 cycles at 10 A/g and 0 ℃. To evaluate the serviceability of the as-prepared electrode materials, the devices in parallel and series connections encapsulated by 3D printing exhibits a stable discharging performance at 0 °C, demonstrating a potential application in cold environment. Heteroatomic intercalating promotes the co-adsorption of hydroxyls on the double active sites of the Ni and Co, resulting in an improved supercapacitance.

Pt-Ni contact engineering in carbon nitride based photocatalysts for hydrogen production

The effect of a binary PtNi co-catalyst supported on graphitic carbon nitride nanosheets is studied in the photo-production of hydrogen from methanol:water mixtures. The physicochemical analysis provides evidence that the carbon nitride support allows the formation of highly dispersed PtNi nanoparticles with an average composition of Pt 85 % Ni 15 %. The binary system outperforms the monometallic Pt and Ni counterparts and renders an extraordinary quantum efficiency of 8.8 % for hydrogen photo-production. The formation of a PtNi alloy, with a Pt-enriched surface and electronic properties influenced by the heterometallic contact, provides high and stable activity, mostly as a consequence of the effects that the co-catalyst exerts on the charge carrier handling capability of the solid.

A facile preparation of graphene hydrogel-supported bimetallic RuM (M: Co, Ni, Cu) nanoparticles as catalysts in the hydrogen generation from ammonia borane

Abstract The synthesis of ultrafine well-dispersed bimetallic RuM (M: Co, Ni, Cu) nanoparticles (NPs) supported on graphene hydrogel (GH) was accomplished by a novel one-pot wet-chemical protocol that comprised the hydrothermal reduction of the mixture of graphene oxide and metal precursors by ethylene glycol (EG) in a Teflon-coated stainless-steel reactor at 180 °C. In this study, for the first time, we report the synthesis of bimetallic RuM NPs anchored on GH during the hydrothermal production of GH from graphene oxide (GH-RuM) and the catalysis of the yielded GH-Ru in the hydrolysis of ammonia borane (AB). As-synthesized GH-RuM (M: Co, Ni, Cu) nanocatalysts were characterized by using many advanced instrumental techniques including TEM, XRD, XPS, and ICP-MS. The bimetallic catalysts denoted as GH-Ru20Co80, GH-Ru30Ni70 and GH-Ru10Cu90 exhibited much higher catalytic activity compared to their Ru, Co, Ni and Cu monometallic counterparts in the hydrolytic dehydrogenation of AB. The catalytic performance of as-prepared NPs in terms of hydrogen generation rate (HGR) was achieved in the order of RuCo > RuNi > RuCu and the highest HGR calculated for the catalyst GH-Ru20Co80 reached 8911.5 mL H2 gcat −1 min−1 at room temperature with an activation energy of 52.5 kJ mol−1.

First-principle studies of oxidation effects on grain boundary strength in nickel

Nickel-base alloys are susceptible to stress corrosion cracking (SCC), in which the fracture mainly propagates along oxidized grain boundaries (GBs). To understand how oxidation degrades GB strength, first-principle-based density functional theory (DFT) calculations are conducted to study three types of interfaces: partially oxidized GBs, fully oxidized GBs, and metal-oxide interface, using Ni as a model system. For partially oxidized GBs, both substitutional and interstitial oxygen atoms of different coverages are inserted at three Ni GBs: Σ3(111) coherent twin, Σ3(112) incoherent twin, and Σ5(210) high-angle GB. The results show that the GB strength decreases almost monotonically with the increasing oxygen coverage at all GBs. Typically, substitutional oxygen causes a stronger embrittlement effect than interstitial oxygen, except at the Σ3(111). In addition, the oxygen-induced mechanical distortion has a smaller contribution to the embrittlement than its chemical effect except for high-coverage oxygen interstitials at the Σ3(111). For the fully oxidized GBs, three NiO GBs of the same types as in Ni are studied. Although the strengths of Σ3(112) and Σ5(210) NiO GBs are much weaker than the Ni counterparts, the Σ3(111) NiO GB has a higher strength than that in Ni. Finally, the strength of a Ni/NiO metal-oxide interface is calculated, which is found to be the weakest one among all interfaces studied in this work, suggesting that metal-oxide interfaces could be favorable crack initiation sites.

Ligand-assisted morphology regulation of AuNi bimetallic nanocrystals for efficient hydrogen evolution.

We report the controllable synthesis of AuNi core-shell (c-AuNi) and Janus (j-AuNi) nanocrystals (NCs) with uniform shape, tunable size and compositions in the presence of trioctylphosphine (TOP) or triphenylphosphine (TPP). The morphology of the AuNi bimetallic NCs could be regulated by varying the structure and concentration of phosphine ligands. The ligand-directed structural evolution mechanism of AuNi bimetallic NCs was investigated and discussed in detail. When loaded on graphitic carbon nitride (GCN) for photocatalytic hydrogen generation, the obtained j-AuNi NCs showed much higher activity for hydrogen evolution than the monometallic (Au and Ni) counterparts, owing to the synergistic effect of plasmon enhanced light absorption from the Au portion and additional electron sink effect from the Ni portion. This work provides a promising route for preparing low-cost Au-based bimetallic catalysts with controllable morphologies and high activities for hydrogen production.

Spherical Ni/Ni3Se2 Heterostructure for Efficient Electrochemical Oxidation Reactions

AbstractA Ni/Ni3Se2 metal‐semiconductor heterojunction catalyst with a sphere structure was prepared by a hydrothermal and hydrogen reduction method. The results showed that the heterostructure Ni/Ni3Se2 exhibits better performance than Ni3Se2 and Ni counterparts for electrochemical oxidation reactions. During electrocatalytic water oxidation, the overpotential is 340 mV to reach a catalytic current density of 10 mA cm−2 in 1.0 M KOH solution. The heterogeneous interface formed between the metal Ni and Ni3Se2 in the Ni/Ni3Se2 catalyst can accelerate the electron transfer in the electrochemical oxidation process. Moreover, the as‐prepared material is also applied for sulfonamide degradation, with the aid from hydroxyl radicals generated during water oxidation. This application is meaningful since the product from water oxidation is not desired in hydrogen production from water electrolysis. The material with heterojunctions delivered degradation efficiency up to 80% of sulfonamide antibiotics within 2 h. Therefore, the Ni/Ni3Se2 material might have application prospects in electrochemical sustainability research.

Total hydrogenation of hydroxymethylfurfural via hydrothermally stable Ni catalysts and the mechanistic study

Total hydrogenation of hydroxymethylfurfural (HMF) (including hydrogenation of both furan ring and carbonyl group) produces 2,5-bis-(hydroxymethyl) tetrahydrofuran (BHTF), which can be used as rigid polymer monomer, green solvent, or precursor of high-value chemicals and has great market potential. Although Ni is regarded as the most selective metal for the total hydrogenation of HMF, Ni catalysts often suffer sintering and leaching under hydrothermal conditions. In this regard, development of hydrothermally stable Ni catalysts is highly desirable. Here, Ni on well mixed oxides (Ni/MgaAl10-aOx) derived from layered double hydroxide (LDH) precursors was successfully synthesized via co-precipitation. The Ni/MgaAl10-aOx showed superior hydrothermal stability during the aqueous phase total hydrogenation of HMF, without noticeable activity loss, leaching and sintering after multiple reuse. In contrast, significant activity loss, leaching and sintering was observed for impregnated Ni counterparts. Catalyst characterization revealed the formation of highly dispersed Ni and well mixed porous oxides after the thermal reduction of the NiMgAl-LDH precursors as well as the stronger metal-support interactions of the NiMgAl-LDH as compared to impregnated Ni catalysts with similar Ni particle size. The markedly improved hydrothermal stability was due to enhanced metal support interactions derived from the LDH precursors, which prevents the undesired agglomeration and leaching of Ni in the hydrothermal environment. Moreover, a high BTHF yield of 99.0% was obtained using the Ni/MgaAl10-aOx under optimal reaction conditions. Density functional theory calculations suggest that the total hydrogenation of HMF over the Ni catalysts proceeds through the alkoxy pathway via “flat-lying” adsorption.

Enhanced interface interaction in Cu2S@Ni core-shell nanorod arrays as hydrogen evolution reaction electrode for alkaline seawater electrolysis

Exploring cheap, efficient and stable electro-catalysts for hydrogen evolution reaction (HER) is a vital technology for seawater splitting development. Herein, we demonstrate that constructing underlying Cu2S nanorod arrays is crucial for improving the HER activity of surface Ni catalyst. Electrochemical results reveal that nickel coated Cu2S nanoarrays (Cu2S@Ni) on copper foam exhibits a preferable HER activity (~500 mA cm−2 at <200 mV overpotential), outperforming Cu2O@Ni and pure Ni counterparts. Detailed analyses indicate that the enhanced HER activity of Cu2S@Ni can be attributed to Ni–S interaction between surface nickel and underlying Cu2S nanorods, which optimizes the adsorption energy of hydrogen on the surface. Moreover, the Cu2S@Ni nanoarray electrode shows a remarkable HER stability, highlighting its promising potential in alkaline seawater electrolysis.

Effects of the Incorporation of Distinct Cations in Titanate Nanotubes on the Catalytic Activity in NOx Conversion.

Effects of the incorporation of Cr, Ni, Co, Ag, Al, Ni and Pt cations in titanate nanotubes (NTs) were examined on the NOx conversion. The structural and morphological characterizations evidenced that the ion-exchange reaction of Cr, Co, Ni and Al ions with the NTs produced catalysts with metals included in the interlayer regions of the trititanate NTs whereas an assembly of Ag and Pt nanoparticles were either on the nanotubes surface or inner diameters through an impregnation process. Understanding the role of the different metal cations intercalated or supported on the nanotubes, the optimal selective catalytic reduction of NOx by CO reaction (SCR) conditions was investigated by carrying out variations in the reaction temperature, SO2 and H2O poisoning and long-term stability runs. Pt nanoparticles on the NTs exhibited superior activity compared to the Cr, Co and Al intercalated in the nanotubes and even to the Ag and Ni counterparts. Resistance against SO2 poisoning was low on NiNT due to the trititanate phase transformation into TiO2 and also to sulfur deposits on Ni sites. However, the interaction between Pt2+ from PtOx and Ti4+ in the NTs favored the adsorption of both NOx and CO enhancing the catalytic performance.

Crystal structure of bis-{2-hy-droxy-N'-[1-(pyrazin-2-yl)ethyl-idene]benzohydrazidato}cadmium(II).

In the title complex mol-ecule, [Cd(C13H11N4O2)2], the Cd atom is coordinated in a distorted octa-hedral geometry by two tridentate ligands synthesized from 2-hy-droxy-benzohydrazide and 1-(pyrazin-2-yl)ethan-1-one. The mol-ecule has twofold crystallographic symmetry and is isomorphous to its Mn, Co, Ni, Cu and Zn counterparts.

THz, Raman, IR and DFT studies of noncentrosymmetric metal dicyanamide frameworks comprising benzyltrimethylammonium cations

We report density functional theory (DFT) studies of vibrational modes for benzyltrimethylammonium cations (BeTriMe+) as well as THz, IR and Raman studies of [BeTriMe][M(dca)3(H2O)] (dca = N(CN)2−, dicyanamide; M = Mn2+, Co2+, Ni2+) and their anhydrous analogues. These studies show that the anhydrous BeTriMeMn and BeTriMeNi have the same or very similar structures and loss of water molecules leads to significant changes in the metal-dicyanamide frameworks. In particular, the number of dca modes decreases, suggesting increase of crystal symmetry, probablly related with decrease in the number of non-equivalent dca bridges from two to one. Although it is possible that dehydration leads to a replacement of the coordinate Mn-O (Ni-O) bonds by Mn-N (Ni-N) bonds, wherein N atoms come from the C≡N groups of previously non-bridged dca units, reversibility of the dehydration process indicates that such new bonds are either not formed or are very weak. The anhydrous Mn and Ni compounds undergo similar reversible phase transitions to lower symmetry phases. The driving force for these transitions is most likely ordering of dca linkers but this process is accompanied by weak distortion of the metal-dicyanamide frameworks. In the case of BeTriMeCo, the loss of water molecules also leads to significant changes in the cobalt-dicyanamide framework. However, the structure of this analogue is different from the structures of the Mn and Ni counterparts, the number of unique dca linkers is preserved and the dehydration process is irreversible, suggesting more drastic rearrangement of the metal-dicynamide framework.

First-principles DFT insights into the adsorption of hydrazine on bimetallic β1-NiZn catalyst: Implications for direct hydrazine fuel cells

We present a systematic first-principles density functional theory study with dispersion corrections (DFT-D3) of hydrazine adsorption on the experimentally observed (111), (110) and (100) surfaces of the binary β1-NiZn alloy. A direct comparison has been drawn between the bimetallic and monometallic Ni and Zn counterparts to understand the synergistic effect of alloy formation. The hydrazine adsorption mechanism has been characterised through adsorption energies, Bader charges, the d-band centre model, and the coordination number of the active site - which is found to dictate the strength of the adsorbate–surface interaction. The bimetallic β1-NiZn nanocatalyst is found to exhibit higher activity towards adsorption and activation of hydrazine compared to the monometallic Ni and Zn counterparts. The Ni-sites of the bimetallic NiZn surfaces are found to be generally more reactive than Zn sites, which is suggested to be due to the higher d-band centre of −0.13 eV (closer to the Fermi level), forming higher energy anti-bonding states through NiN interactions. The observed synergistic effects derived from surface composition and electronic structure modification from Ni and Zn alloying should provide new possibilities for the rational design and development of low-cost bimetallic Ni-Zn alloy catalysts for direct hydrazine fuel cell (DHFC) applications.

Visible-Light-Driven, Nickel-Doped Cobalt Oxides/Hydroxides Actuators with High Stability.

Material-based, light-driven actuators have been a recent research focus for the development of untethered, miniaturized devices and microrobots. Recently introduced nickel hydroxide/oxyhydroxide (Ni(OH)2/NiOOH) and cobalt oxides/hydroxides (CoOx(OH)y) are promising light-driven actuators, as they exhibit large and rapid actuation response and are inexpensive to fabricate by fast electrodeposition. However, as their actuation is due to the volume change accompanying the light-induced desorption of intercalated water in their turbostratic structures, their actuation reduces over time as crystallization takes place slowly, which lowers the amount of water held. Here, we introduce nickel-doped cobalt oxides/hydroxides (NiCoOx(OH)y) actuator that exhibits similar turbostratic crystal structures and actuation magnitude as CoOx(OH)y, but with much slower crystallization and hence significantly more stable actuation than CoOx(OH)y or Ni(OH)2/NiOOH. The new actuator exhibits much better applicability than the Co and Ni counterparts, and the present work shows that a stabilized turbostratic structure is a key for achieving high light-driven actuation in transition-metal oxide/hydroxide actuators.

From NiRh2O4 to RhNi Alloy: Preparation and Characterization of Nanofibers for Hydrogen Evolution in pH-Universal Media

Considering the growing attention to sustainable hydrogen production from water splitting, advanced materials for electrocatalytic water splitting are central to the area of renewable energy. Ideal water splitting catalysts should have not only low overpotential to produce hydrogen but also decent stability for a controlled period. While the previously reported water splitting catalysts have various compositions, the ones based on earth-abundant and non-precious metals are being studied extensively for hydrogen and oxygen production. However, noble metal oxides, in general, still exhibit superior electrocatalytic activity and enhanced stability under extreme environment compared with other cheap metals. Therefore, mixing non-precious transition metals (e.g. Ni, Co and Cu) with noble metals could be a possible strategy to utilize highly active but expensive noble metals providing economic feasibility.Here we present the synthetic processes and physical/electrochemical characterization of single-phase NiRh2O4 nanofibers (NFs) and their reduced form, RhNi NFs. Those NFs are synthesized through electrospinning, a simple way to facilitate 1D nanostructure, and post-thermal annealing process with and without hydrogen atmosphere. Under a certain optimized condition, single-phase NiRh2O4 NFs and single-phase alloy RhNi NFs are synthesized without and with hydrogen atmosphere, respectively. To find the proper synthetic conditions, NFs are electrospun with varying the precursor mixing ratios and calcined at different temperatures. The morphology and compositions of NiRh2O4 NFs and RhNi NFs were characterized by a field emission scanning electron microscope (FESEM) equipped with an energy dispersive X-ray spectrometer (EDS), high-resolution transmission electron microscopy (HRTEM) and X-ray photoelectron spectroscopy (XPS). The crystalline structure of the prepared NFs are investigated through high-resolution X-ray diffraction (XRD). Electrochemical activities of NiRh2O4 NFs and RhNi NFs for hydrogen evolution reaction (HER) are studied with rotating disk electrode (RDE) voltammetry in N2-saturated 1.0 M NaOH, 1.0 M PBS and 1.0 M HClO4 aqueous solutions; and compared with those of pure metallic Rh, Ni counterparts in addition to commercial Pt/C. This work was financially supported by the National Research Foundation of Korea (NRF) funded by the Ministry of Science and ICT (NRF-2019R1F1A1059969 for CL) and Basic Science Research Program through the NRF funded by the Ministry of Education (NRF-2018R1A6A1A03025340 for YL and KMH).

Identifying the role of Ni and Fe in Ni–Fe co-doped orthorhombic CoSe2 for driving enhanced electrocatalytic activity for oxygen evolution reaction

Exploring the origin of high electrocatalytic activity of Ni–Fe–Co ternary selenides for oxygen evolution reaction (OER) is of fundamental importance for rational design of efficient electrocatalysts. In this report, we synthesize self-assembled microspheres by orthorhombic CoSe2 nanorods along with the Ni and/or Fe doped counterparts, and systematically investigate their electrocatalytic performance. The results show that, although either Ni-doping or Fe-doping can significantly enhance the catalytic activity of CoSe2, the ways they promote catalytic activity are different. The Tafel analysis demonstrates that Fe incorporation leads to a kinetics change in the OER while Ni incorporation has little effect. Based on the electrochemical characterizations and theoretical calculations, Ni-doping maintains Co active sites and does not alter the OER mechanism, but decreases the energy barrier of the rate-limiting step by modifying Co active sites. In contrast, Fe-doping transforms the active sites from Co to Fe, and the rate-limiting step changes to the O–OH formation stage, thus affording faster reaction kinetics. These findings are further confirmed by more Ni–Fe co-doped CoSe2 with various content of Ni and Fe. Specifically, under the optimal experimental conditions, Ni–Fe co-doped CoSe2 (Ni0.04Fe0.16Co0.8Se2) exhibits a remarkable OER activity with an overpotential of ∼230 mV at 10 mA cm−2 and Tafel slope of 39 mV dec−1.

Transfer hydrogenation from glycerol over a Ni-Co/CeO2 catalyst: A highly efficient and sustainable route to produce lactic acid

Bimetallic Ni-Co catalysts supported on nanosized CeO2 were prepared and investigated as heterogeneous catalysts for the transfer hydrogenation between glycerol and various H2 acceptors (levulinic acid, benzene, nitrobenzene, 1-decene, cyclohexene) to selectively produce lactic acid (salt) and the target hydrogenated compound. The bimetallic NiCo/CeO2 catalyst showed much higher activity than the monometallic Ni or Co counterparts (with equal total metal mass), thus indicating strong synergetic effects. The interaction between the metallic sites and the CeO2 support was thoroughly characterised by means of transmission electron microscopy (TEM), scanning transmission electron microscopy (STEM), energy-dispersive X-ray spectroscopy (EDX) mapping, X-ray photoelectron spectroscopy (XPS), hydrogen-temperature programmed reduction (H2-TPR) and X-ray diffraction (XRD). Combining characterisation and catalytic results proved that the Ni species are intrinsically more active than Co species, but that incorporating Co into the catalyst formulation prevented the formation of large Ni particles and led to highly dispersed metal nanoparticles on CeO2, thus leading to the observed enhanced activity for the bimetallic system. The highest yield of lactic acid (salt) achieved in this work was 93% at 97% glycerol conversion (160 °C, 6.5 h at 20 bar N2, NaOH: glycerol = 1.5). The NiCo/CeO2 catalyst also exhibited high activity and selectivity towards the target hydrogenated products in the transfer hydrogenation reactions between glycerol and various H2 acceptors. Batch recycle experiments showed good reusability, with retention of 80% of the original activity after 5 runs.

Enhanced bimetallic Rh-Ni supported catalysts on alumina doped with mixed lanthanum-cerium oxides for ethanol steam reforming

Enhanced bimetallic Rh (0.25, 0.5, 0.75, 1.0 wt%)-Ni 10 wt%) promoted with La2O3(15 wt%) and CeO2(10 wt%)/alumina supported catalysts for ethanol steam reforming compared to their monometallic counterparts is reported. The larger stability of bimetallic Rh-Ni supported catalysts can be due to a: i) cooperative effect of Rh and Ni activities; ii) larger capacity to gasify the methyl group produced from the decomposition of the intermediaries, iii) non-accumulation of acetate species and, iv) favoring the WGS reaction. The 1%Rh-10%Ni bimetallic catalyst shows the best catalytic performance towards H2 selectivity, operating stability over 144 h of reaction and almost non-carbon formation after 24 h on steam. A significant decrease in the carbon-deposition of the 1%Rh-10 wt%Ni bimetallic catalyst, displaying a 70- and 560-times larger stability than their respective monometallic 1%Rh and 10%Ni counterparts was detected. The study of deactivation/regeneration process of the 1%Rh-10%Ni catalytic system indicates that a reactivation treatment fully recovered the catalytic activity of the deactivated catalyst at least in two regeneration cycles. In both cycles, the bimetallic 1%Rh-10%Ni catalyst was stable until 72 h of reaction appearing as a promising catalyst for the reaction of reforming ethanol at mild temperature conditions.

CuNi NPs supported on MIL-101 as highly active catalysts for the hydrolysis of ammonia borane

The catalysts containing Cu, Ni bi-metallic nanoparticles were successfully synthesized by in-situ reduction of Cu2+ and Ni2+ salts into the highly porous and hydrothermally stable metal-organic framework MIL-101 via a simple liquid impregnation method. When the total amount of loading metal is 3×10−4mol, Cu2Ni1@MIL-101 catalyst shows higher catalytic activity comparing to CuxNiy@MIL-101 with different molar ratio of Cu and Ni (x, y=0, 0.5, 1.5, 2, 2.5, 3). Cu2Ni1@MIL-101 catalyst has the highest catalytic activity comparing to mono-metallic Cu and Ni counterparts and pure bi-metallic CuNi nanoparticles in hydrolytic dehydrogeneration of ammonia borane (AB) at room temperature. Additionally, in the hydrolysis reaction, the Cu2Ni1@MIL- 101 catalyst possesses excellent catalytic performances, which exhibit highly catalytic activity with turn over frequency (TOF) value of 20.9molH2min−1 Cumol−1 and a very low activation energy value of 32.2kJmol−1. The excellent catalytic activity has been successfully achieved thanks to the strong bi-metallic synergistic effects, uniform distribution of nanoparticles and the bi-functional effects between CuNi nanoparticles and the host of MIL-101. Moreover, the catalyst also displays satisfied durable stability after five cycles for the hydrolytically releasing H2 from AB. The non-noble metal catalysts have broad prospects for commercial applications in the field of hydrogen-stored materials due to the low prices and excellent catalytic activity.