Source rock geochemistry of central and northwestern Niger Delta: Inference from aromatic hydrocarbons content

The influence of origin, depositional environment and thermal maturity of organic matter on the occurrence of aromatic hydrocarbons in source rocks from the central and northwestern Niger Delta was investigated. Eighty two source rock samples from four oil wells in the central and northwestern Niger Delta were analyzed for the aromatic hydrocarbon content using gas chromatography-mass spectrometry (GC-MS). The results of analysis of aromatic hydrocarbon fractions of the source rock extracts show the presence of many classes of aromatic hydrocarbons, which include naphthalenes, phenanthrenes, biphenyls, dibenzothiophenes and fluorenes. Trimethylnaphthalene (TMN) is the most abundant among the naphthalenes while dimethylphenanthrene (DMP) is the most abundant among the phenanthrenes. Among the biphenyls, 3-methylbiphenyl (3 MB) is the most abundant while 4-methyldibenzothiophene (4MDBT) is the most abundant among the dibenzothiphenes. Only two fluorenes were detected, and fluorene is more in abundance than 1-methylfluorene (1 MF). Depositional environment indicators of aromatic hydrocarbon organic matter reveal that the organic materials in the source rocks in these wells were deposited in marine-to-swamp depositional environments under reducing to suboxic conditions. Thermal maturity indicators calculated from the abundance of the aromatic hydrocarbons indicate that the source rock samples are thermally mature. Most of the source rocks are at the peak of oil window while a few at the early oil window. Source rocks from wells GB, OP and OT in the central Niger Delta are thermally more mature than those from well AW in the northwestern Niger Delta.

Towards maximized utilization of iridium for the acidic oxygen evolution reaction

The reduction in noble metal content for efficient oxygen evolution catalysis is a crucial aspect towards the large scale commercialisation of polymer electrolyte membrane electrolyzers.Since catalytic stability and activity are inversely related,long service lifetime still demands large amounts of low-abundant and expensive iridium.In this manuscript we elaborate on the concept of maximizing the utilisation of iridium for the oxygen evolution reaction.By combining different tin oxide based support materials with liquid atomic layer deposition of iridium oxide,new possibilities are opened up to grow thin layers of iridium oxide with tuneable noble metal amounts.In-situ,time-and potential-resolved dissolution experiments reveal how the stability of the substrate and the catalyst layer thickness directly affect the activity and stability of deposited iridium oxide.Based on our results,we elaborate on strategies how to obtain stable and active catalysts with maximized iridium utilisation for the oxygen evolution reaction and demonstrate how the activity and durability can be tailored correspondingly.Our results highlight the potential of utilizing thin noble metal films with earth abundant support.materials for future catalytic applications in the energy sector.

Synthesis of gadolinium aluminate thin film by ion beam sputtering sequential deposition

Sequentially deposited by thin film synthesis consisted of multilayer precursor film deposition and thermal treatment. It is especially useful in complex-ingredient or precise stoichoimetric controlling thin film synthesis. Gadolinium aluminate,a new good candidate system for many luminescence usages other than laser crystals,scintillation crystals,phosphors,contains many phases,such as Gd4Al2O9(GAM) ,GdAlO3(GAP) ,Gd3Al5O12(GAG) ,so precise stoichoimetry of the amorphous ingredient layers is very important to the final single phase film synthesis. In our work,Gd2O3 and Al amorphous layers(ingredients for gadolinium aluminate film) were deposited in a certain sequence on MgO(100) and Si(100) substrate by IM100(an ion beam sputtering instrument) . The multi-amorphous-layered precursor was annealed with two-step thermal treatment(diffusion at a low temperature and then crystallization at a high temperature) . The XRD(X-ray diffraction pattern) ,SEM(scanning electron microscope second electron image) and AES(Auger electron spectroscopy depth profiles) analyses were used to detect the film microstructures and properties. The analyses results showed that ion beam sputtering deposition could control ingredient stoichoimetric ratio by an in site depositing thickness measurement. During the two-step thermal treatment,diffusion at a low temperature would cost a rather long time to make the amorphous precursor film uniform(more than 120 h) ,and the suitable diffusion temperature should be around 400 oC. The crystallization temperature should be decided by the gadolinium aluminate phase types and cost rather less time(about 4 h) . The stable phases GAP and GAM should be annealed at 1300 oC or higher temperatures,but the metastable phase GAG should just be annealed at around 1100 °C.