Nickel based nanoalloys as reduction electrocatalysts for solar fuel production

In order to optimise the efficiency of solar fuel devices, development of cheap, active and stable reduction electrocatalysts for solar fuel production is crucial. To this end, ligand stabilised nickel nanoalloys of around 10 nm with relatively small size distributions, have been synthesised for a variety of compositions utilising first row transition metals (Cr, Fe, Co and Cu). Bi- and trimetallic nanoalloys have been synthesised and good control over composition was demonstrated. Synthesised nanoalloys were electrochemically tested to assess their proton and CO2 reduction activities. All nanoalloys showed higher hydrogen evolution reaction (HER) activity than pure nickel. For bimetallic nanoalloys, in pH 1, a general increase in HER activity with increased electron negativity was observed. The Ni0.5Cu0.3Co0.2 nanoalloy showed the highest HER activity at pH 1, whereas the Ni0.5Co0.3Fe0.2 nanoalloy was most active for HER in pH 13. Little difference between the activities for all nanoalloys was observed at pH 7. The nanoalloys showed differing selectivity’s for CO2 reduction products. Solution based CO2 reduction products were detected at low overpotentials (below -0.789 V vs RHE, pH 6.8), although low faradaic efficiencies (< 1%) were observed. High resolution scanning electron microscopy (HR-SEM) was used to attempt to analyse the nanoalloys after deposition onto the electrodes and after electrochemical testing. The results indicated the presence of sub-monolayer coverage, therefore increasing the nanoalloy coverage without large amounts of agglomeration occurring could result in the observation of higher current densities at lower overpotentials. The stability of the nanoalloy electrodes was also investigated and no decrease in HER activity was observed over 12 hours at -0.5 V vs RHE. Moreover, repeated cycling resulted in an increase in activity being observed. This may be due to leaching of elements overtime. A procedure has been developed using a range of techniques to analyse nanoalloy composition, test proton and CO2 reduction activities and assess stability. This has not only allowed for direct comparison between different materials studied, it also provides a framework for future investigations of nanoalloys for (photo)electrochemical proton and CO2 reduction

Evaluasi Padang Penggembalaan Alami Maronggela Di Kabupaten Ngada Provinsi Nusa Tenggara Timur

&nbsp;Evaluasi terhadap padang penggembalaan alami untuk memperbaiki kualitas hijauan merupakan salah satustrategi penting dalam peningkatan produksi ternak ruminansia. Penelitian ini bertujuan untuk menyediakandatabase tentang kondisi padang penggembalaan serta pengelolaan padang penggembalaan yang baik di KabupatenNgada. Kabupateng Ngada merupakan daerah yang sangat potensial bagi pengembangan ternak sapi karenamemiliki padang penggembalaan yang luas. Penelitian dilakukan di padang penggembalaan alami MaronggelaKabupaten Ngada, Provinsi Nusa Tenggara Timur, yang berlangsung selama 2 musim, yaitu pada akhir musimhujan (bulan Maret) dan akhir musim kemarau (bulan Oktober). Peubah yang diamati pada penelitian ini adalahkomposisi botani dan kualitas hijauan. Padang penggembalaan alami Maronggela didominasi oleh hijauan jenisImperata cylindrica dan Themeda aguens, produksi dan kualitas hijauan tertinggi di akhir musim hujan, sertaproduksi dan kualitas terendah di akhir musim kemarau. Daya tampung padang penggembalaan alami Maronggeladalam satu tahun adalah 1,5 satuan ternak. Kata kunci: database, padang pengembalaan, sap

Zirconium−nitrogen intermolecular frustrated Lewis pairs

A series of intermolecular transition metal frustrated Lewis pairs (FLPs) based on zirconocene alkoxide complexes ([Cp2Zr­(OMes)]+ 1 or ([Cp*2Zr­(OMes)]+ 2) with nitrogen Lewis bases (NEt3, NEtiPr2, pyridine, 2-methylpyridine, 2,6-lutidine) are reported. The interaction between Zr and N depends on the specific derivatives used, in general more sterically encumbered pairs leading to a more frustrated interaction; however, DOSY NMR spectroscopy reveals these interactions to be dynamic in nature. The pairs undergo typical FLP-type reactivity with D2, CO2, THF, and PhCCD. The catalytic dehydrocoupling of Me2NH·BH3 is also reported. Comparisons can be made with previous work employing phosphines as Lewis bases suggesting that hard–hard or hard–soft acid–base considerations are of little importance compared to the more prominent roles of steric bulk and basicity

Rhenium Complexes Bearing Tridentate and Bidentate Phosphinoamine Ligands in the Production of Biofuel Alcohols via the Guerbet Reaction

We report a variety of rhenium complexes supported by bidentate and tridentate phosphinoamine ligands and their use in the formation of the advanced biofuel isobutanol from methanol and ethanol. Rhenium pincer complexes 1–3 are effective catalysts for this process, with 2 giving isobutanol in 35% yields, with 97% selectivity in the liquid fraction, over 16 h with catalyst loadings as low as 0.07 mol %. However, these catalysts show poorer overall selectivity, with the formation of a significant amount of carboxylate salt solid byproduct also being observed. Production of the active catalyst 1d has been followed by 31P NMR spectroscopy, and the importance of the presence of base and elevated temperatures to catalyst activation has been established. Complexes supported by diphosphine ligands are inactive for Guerbet chemistry; however, complexes supported by bidentate phosphinoamine ligands show greater selectivity for isobutanol formation over carboxylate salts. The novel complex 7 was able to produce isobutanol in 28% yield over 17 h. The importance of the N–H moiety to the catalytic performance has also been established, giving further weight to the hypothesis that these catalysts operate via a cooperative mechanism

Boron–nitrogen main chain analogues of polystyrene:poly(<i>B</i>-aryl)aminoboranes via catalytic dehydrocoupling

High molecular weight B-arylated polyaminoboranes are obtained via catalytic dehydropolymerisation of B-aryl amine–boranes and represent the first inorganic polystyrene analogues with a B–N main chain.</p

Lamotrigine ethanol monosolvate

Lamotrigine is an active pharmaceutical ingredient used as a treatment for epilepsy and psychiatric disorders. Single crystals of an ethanolate solvate, C9H7Cl2N5·C2H5OH, were produced by slow evaporation of a saturated solution from anhydrous ethanol. Within the crystal structure, the lamotrigine molecules form dimers through N—H...N hydrogen bonds involving the amine N atoms in the ortho position of the triazine group. These dimers are linked into a tape motif through hydrogen bonds involving the amine N atoms in the para position. The ethanol and lamotrigine are present in a 1:1 ratio in the lattice with the ethyl group of the ethanol molecule exhibiting disorder with an occupancy ratio of 0.516 (14):0.484 (14)

Heterometathesis of diphosphanes (R2P–PR2) with dichalcogenides (R′E–ER′, E = O, S, Se, Te)

The reactions of R2P–PR2 with R′E–ER′, (where E = Se, S, O, Te) to give R2P–ER′ have been explored experimentally and computationally. The reaction of Ph2P–PPh2 with PhSe–SePh gives Ph2P–SePh (1) rapidly and quantitatively. The P–P/Se–Se reaction is inhibited by the addition of the radical scavenger TEMPO which is consistent with a radical mechanism for the heterometathesis reaction. Compound 1 has been fully characterised, including by X-ray crystallography. A range of other Ar2P–SeR (R = Ph, nBu or CH2CH2CO2H) have also been prepared and characterised. The reaction of 1 with [Mo(CO)4(nbd)] (nbd = norbornadiene) gives two products which, from their characteristic 31P NMR data, have been identified as cis-[Mo(CO)4(Ph2PSePh–P)2] (8) and the mixed-donor complex cis-[Mo(CO)4(Ph2P–SePh–P)(Ph2P–SePh–Se)] (9). It is deduced that the P and Se atoms in ligand 1 have comparable capacity to coordinate to Mo(0). The reaction of Ph2P–PPh2 with PhS–SPh gives Ph2P–SPh (2) quantitatively but no reaction was observed between Ph2P–PPh2 and PhTe–TePh. Heterometathesis between Ph2P–PPh2 and tBuO–OtBu does not occur thermally but has been observed under UV irradiation to give Ph2P–OtBu along with P(V) oxidation by-products. DFT calculations have been carried out to illuminate why heterometatheses with dichalcogenides R′E–ER′ occur readily when E = S and Se but not when E = O and Te. The calculations show that heterometathesis is predicted to be thermodynamically favourable for E = O, S and Se and unfavourable for E = Te. The fact that a metathesis reaction between Ph2P–PPh2 with tBuO–OtBu is not observed in the absence of UV radiation, is therefore due to kinetics