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A series of novel terpyridine derivatives of benzofuran (NP1–NP3) were synthesised by simple multicomponent one pot reaction among benzofuran-2-carbaldehyde, ammonium hydroxide and three different derivatives of acetyl pyridine with isolated yield up to 98%. All the synthesised molecules were characterised by NMR, HRMS, IR spectroscopies and single crystal XRD (CIF file CCDC no. 2078532 for TP1). Cu(II) complexes were prepared selectively with terpyridine derivative of 2-acetyl pyridine and characterised by single crystal XRD (CIF file CCDC no. 1525025 for TP-Cu). UV−Vis spectral studies were performed with all the prepared molecules. [ABSTRACT FROM AUTHOR]

Ruthenium nanoparticles (NPs) supported over carbon thin films (Ru/C thin films) catalysts were synthesized by pulsed laser deposition and used as catalysts for hydrolysis of ammonia borane (AB). Highly irregular and porous carbon films with high surface area were deposited by varying Ar gas pressures during the deposition. By taking the advantage of phase explosion phenomena, occurring at high laser fluence, the surface of the carbon films were decorated with crystalline Ru NPs with size below ∼10 nm. Ru/C thin film catalyst produced H 2 with 6 times higher H 2 generation rate as compared to unsupported Ru NPs assembled film, and with a high turnover frequency value of 70.5 mol H 2 mol −1 Ru min −1 . A combination of morphological features and high content of sp 2 bonded C atoms provides good dispersion of Ru NPs over a large surface area. Both these features contribute in generating large number of active sites leading to the increase in catalytic efficiency. A possibility of using the present form of catalyst as an ON/OFF switch for H 2 production was also tested. Although the catalytic activity decreased with the number of hydrolysis cycles, Ru/C thin film catalyst was able to generate the expected amount of H 2 gas in each cycle when it was reused several times. The observed low activation energy (∼28 kJ mol −1 ) and high H 2 generation rate (15.5 L H 2 min −1 g −1 of Ru) by hydrolysis of AB suggest that Ru/C thin film catalyst is highly efficient. [ABSTRACT FROM AUTHOR]

Highlights: [•] Co-B catalyst particles were supported over three type of mesoporous silica of different pore sizes. [•] Co-B supported over SBA-15 showed highest H2 generation rate for hydrolysis of AB. [•] Confinement of Co-B within the pores creates smaller NPs (6nm) with uniform size distribution. [•] Thicker pore walls of SBA-15 avoid agglomeration of Co-B NPs at elevated temperature (873K). [Copyright &y& Elsevier]

Abstract: Co–M–B–P quaternary alloy catalyst powders (where M = Cr, Mo, W, and Cu) were synthesized by chemical reduction method to improve the catalytic performance of Co–B catalyst for hydrogen production by hydrolysis of Ammonia Borane (AB). The catalytic activity increases significantly due to the combined promoting effects induced by M and P in quaternary alloy as compared to binary Co–B catalyst. The promoting roles of each doping element in Co–B catalyst during AB hydrolysis were studied using XPS, XRD, SEM, and BET surface area analyses. Each transition element, present in the form of either oxides or metal, acts as an atomic barrier to prevent Co–B particle agglomeration to increase the effective surface area. At the same time these species also act as Lewis acid sites to improve the absorption of the reactants on to the surface. Inclusion of phosphorous, in addition, is able to create higher number of Co-active sites on the surface, which was inferred from XPS analysis. Among all the alloy catalysts, Co–Cr–B–P showed the highest H2 generation rate, which was mainly attributed to the collective effects of Cr and P in forming the catalyst surface having higher surface area and more Co-active sites. On the contrary, in the case of Cu doped Co–B catalyst, the inclusion of P considerably lowers the surface area, which decreases the catalytic activity. [Copyright &y& Elsevier]

Systematic studies of Co-Mo-B-P alloy catalysts, synthesized by chemical reduction methods, were conducted for H generation by hydrolysis of ammonia borane (AB). The molar concentrations of Mo and P were optimized in the alloy to obtain the best catalytic activity. The combined promoting effects induced by Mo and P in the quaternary alloy caused the H generation rate to increase by ~7.5 times as compared to the undoped-Co-B catalyst. XPS, XRD, SEM, and BET surface area analyses were carried out to understand the promoting role of each dopant element during AB hydrolysis. In the Co-Mo-B-P alloy catalyst, Mo in form of oxides acts as an atomic barrier to avoid Co-B particles agglomeration to preserve the effective surface area. These oxidized species also act as Lewis acid sites to enhance the absorption of reactant to further assist the hydrolysis reaction over alloy catalysts. The role of P in the alloy catalyst is to create a higher number of Co active sites on the catalyst surface as confirmed by XPS. These combined promoting effects provided by P and Mo doping in the Co-B catalyst reduce the activation energy to the lowest value (23 kJ/mol) in the hydrolysis of AB. [ABSTRACT FROM AUTHOR]

Abstract: The catalytic performance of transition metal-doped Co–B ternary alloys were tested for H2 generation by hydrolysis of Ammonia Borane (AB). Chemical reduction method was used to dope Co–B catalyst with various transition metals, namely Cu, Cr, Mo, and W, using their corresponding metal salts. All transition metals induce significant promoting effects on the Co–B catalyst by increasing the H2 generation rate by about 3–6 times as compared to the undoped catalyst. The effect of metal dopant concentration on overall catalyst structure, surface morphology, and catalytic efficiency were examined by varying the metal/(Co + metal) molar ratio. Characterizations such as XPS, XRD, SEM, BET surface area measurement, and particle size analysis were carried out to understand the promoting role of each dopant metal during AB hydrolysis. Dopant transition-metals, in either oxidized or/and metallic state, act as an atomic barrier to avoid Co–B particle agglomeration thus preserving the effective surface area. In addition, the oxidized species such as Cr3+, Mo4+, and W4+, act as Lewis acid sites to enhance the absorption of OH− group to further assist the hydrolysis reaction over alloy catalysts. The promoting nature of transition metal dopants in Co–B alloy powders is demonstrated by the evaluated low activation energy of the rate limiting step and high H2 generation rate (2460 ml H2 min−1 (g of catalyst)−1 for Co–Mo–B) in the hydrolysis of AB. [Copyright &y& Elsevier]

Abstract: Co-P-B catalyst coatings have been synthesized on Ni-foam by using electroless deposition (ED) and their catalytic activity was investigated by catalytic dehydrogenation of ammonia borane (AB, NH3BH3) for H2 generation. Co-P-B catalyst (both in form of powder and coating) showed superior catalytic activity in hydrolysis reaction of AB than that of Co-B powder, with complete evolution of H2 (97%) at very high rate (2l/min/gcatalyst). This was mainly attributed to synergic effect caused by B and P over Co active sites to lower the activation energy of the process. For thermolysis reaction, it was observed that AB loaded on Co-P-B/Ni catalyst releases first mole of H2 at considerably low temperature starting at 50°C and with desorption peak centered at 80°C. To our knowledge this value is the lowest reported for solid state catalyst. Moreover, the catalytic thermolysis did not present any induction time and minimizes the formation of undesirable byproduct like borazine and ammonia. The present result suggests that Co-P-B coated on Ni is a highly efficient and low cost catalyst and can be used for both hydrolysis as well as thermolysis reaction of NH3BH3 with the important advantage that it can be easily recovered and repeatedly reused. [Copyright &y& Elsevier]

Abstract: Nanoparticle-assembled Co-B thin films were synthesized by Pulsed Laser Deposition (PLD) and used as catalysts for the hydrolysis of NH3BH3 (ammonia borane, AB) to produce molecular hydrogen. Amorphous Co-B-based catalyst powders, produced by chemical reduction of cobalt salts, were used as target material for Co-B thin film catalysts preparation through PLD. Surface morphology of Co-B powder and film catalyst was studied using Scanning Electron Microscopy (SEM) and Atomic Force Microscopy (AFM). Compositional and structural characterizations were carried out using X-photoelectron spectroscopy (XPS) and X-ray diffraction (XRD) techniques, respectively. The efficiency of both powder and film catalysts was tested by comparative kinetic analysis of the AB hydrolysis for hydrogen production. It was observed that nanoparticles produced during the laser ablation process act as active catalytic centers to produce significantly higher rate (about 6 times) of H2 than the same amount of the corresponding Co-B powders. Almost complete conversion (95%) of AB was obtained, as confirmed by 11B NMR, by using Co-B films at room temperature. Active Co-B nanoparticles on the surface of the PLD-deposited films is able to decrease the activation energy, for hydrolysis of AB, to the very low value of 34kJmol−1. We also found that by adding small amount of NaBH4 to the NH3BH3 solution increases the efficiency of the Co-B catalyst films, thus generating H2 with higher rate. Maximum H2 generation rate of about ∼8.2LH2 min−1 (g of Co)−1 and ∼13LH2 min−1 (g of Co)−1 was measured by hydrolysis of AB and mixture of (AB+NaBH4) solutions, respectively. [Copyright &y& Elsevier]

We present NH[sub 3](1,1) and (2,2) observations of MBM 12, the closest known molecular cloud (65-pc distance), aimed at finding evidence for on-going star formation processes. No local temperature (with a T[sub rot] upper limit of 12 K) or linewidth enhancement is found, which suggests that the area of the cloud that we have mapped (∼15-arcmin size) is not currently forming stars. Therefore this nearby ‘starless’ molecular gas region is an ideal laboratory to study the physical conditions preceding new star formation. A radio continuum source has been found in Very Large Array archive data, close to but outside the NH[sub 3] emission. This source is likely to be a background object. [ABSTRACT FROM AUTHOR]