Conversion of γ-Valerolactone to Ethyl Valerate over Metal Promoted Ni/ZSM-5 Catalysts : Influence of Ni0/Ni2+ Heterojunctions on Activity and Product Selectivity

Promoter (Cr, Mo and W) modified Ni/ZSM-5 catalysts were explored in the vapor phase conversion of γ-valerolactone (GVL) to ethyl valerate (EV; gasoline blender) at atmospheric pressure. Among the three different promoters (Cr, Mo and W) tested the Mo-modified catalyst was found to be the best candidate. In addition, this catalyst was found to be stable up to 50 h reaction time with an insignificant decrease in activity. The good catalytic performance is related to an optimal ratio of acid and hydrogenation functions provided by Ni2+ and Ni0, respectively. In situ FTIR spectroscopic studies revealed a strong adsorption of GVL on all catalysts which quickly reacts with dosed ethanol by formation of EV, most pronounced on the Mo-modified catalyst, while VA was identified as side product. These findings suggest the preferred GVL ring opening by cracking the C−O bond on the methyl side of the GVL molecule on this type of catalysts leading to pentenoic acid as intermediate, which is quickly hydrogenated and esterified. © 2019 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA

Impact of surface defects on LaNiO3 perovskite electrocatalysts for the oxygen evolution reaction

Perovskite oxides are regarded as promising electrocatalysts for water splitting due to their cost-effectiveness, high efficiency and durability in the oxygen evolution reaction (OER). Despite these advantages, a fundamental understanding of how critical structural parameters of perovskite electrocatalysts influence their activity and stability is lacking. Here, we investigate the impact of structural defects on OER performance for representative LaNiO3 perovskite electrocatalysts. Hydrogen reduction of 700¿°C calcined LaNiO3 induces a high density of surface oxygen vacancies, and confers significantly enhanced OER activity and stability compared to unreduced LaNiO3; the former exhibit a low onset overpotential of 380 mV at 10 mA¿cm-2 and a small Tafel slope of 70.8 mV¿dec-1. Oxygen vacancy formation is accompanied by mixed Ni2+/Ni3+ valence states, which quantum-chemical DFT calculations reveal modify the perovskite electronic structure. Further, it reveals that the formation of oxygen vacancies is thermodynamically more favourable on the surface than in the bulk; it increases the electronic conductivity of reduced LaNiO3 in accordance with the enhanced OER activity that is observed.Peer ReviewedPostprint (author's final draft

Oxygen-deficient photostable Cu2O for enhanced visible light photocatalytic activity

Oxygen vacancies in inorganic semiconductors play an important role in reducing electron-hole recombination, which may have important implications in photocatalysis. Cuprous oxide (Cu2O), a visible light active p-type semiconductor, is a promising photocatalyst. However, the synthesis of photostable Cu2O enriched with oxygen defects remains a challenge. We report a simple method for the gram-scale synthesis of highly photostable Cu2O nanoparticles by the hydrolysis of a Cu(i)-triethylamine [Cu(i)-TEA] complex at low temperature. The oxygen vacancies in these Cu2O nanoparticles led to a significant increase in the lifetimes of photogenerated charge carriers upon excitation with visible light. This, in combination with a suitable energy band structure, allowed Cu2O nanoparticles to exhibit outstanding photoactivity in visible light through the generation of electron-mediated hydroxyl (OH) radicals. This study highlights the significance of oxygen defects in enhancing the photocatalytic performance of promising semiconductor photocatalysts.V. B. thanks the Australian Research Council (ARC) for a Future Fellowship (FT140101285) and funding support through an ARC Discovery (DP170103477). ARC is also acknowledged for DECRA Fellowships to E. D. G. (DE170100164) and J. v. E. (DE150100427) and a Future Fellowship to N. C. (FT1401000834). M. S. acknowledges RMIT University for an Australian Postgraduate Award (APA). A. E. K., E. D. G., P. R. and R. R. acknowledge RMIT University for Vice Chancellor Fellowships. V. B. recognizes the generous support of the Ian Potter Foundation toward establishing an Ian Potter NanoBioSensing Facility at RMIT University. The authors acknowledge the support from the RMIT Microscopy and Microanalysis Facility (RMMF) for technical assistance and providing access to characterization facilities. This work was also supported by the ARC Centre of Excellence for Nanoscale BioPhotonics (CE140100003)

Laying waste to mercury: inexpensive sorbents made from sulfur and recycled cooking oils

Mercury pollution threatens the environment and human health across the globe. This neurotoxic substance is encountered in artisanal gold mining, coal combustion, oil and gas refining, waste incineration, chloralkali plant operation, metallurgy, and areas of agriculture in which mercury-rich fungicides are used. Thousands of tonnes of mercury are emitted annually through these activities. With the Minamata Convention on Mercury entering force this year, increasing regulation of mercury pollution is imminent. It is therefore critical to provide inexpensive and scalable mercury sorbents. The research herein addresses this need by introducing low-cost mercury sorbents made solely from sulfur and unsaturated cooking oils. A porous version of the polymer was prepared by simply synthesising the polymer in the presence of a sodium chloride porogen. The resulting material is a rubber that captures liquid mercury metal, mercury vapour, inorganic mercury bound to organic matter, and highly toxic alkylmercury compounds. Mercury removal from air, water and soil was demonstrated. Because sulfur is a by-product of petroleum refining and spent cooking oils from the food industry are suitable starting materials, these mercury-capturing polymers can be synthesised entirely from waste and supplied on multi-kilogram scales. This study is therefore an advance in waste valorisation and environmental chemistry.Max J. H. Worthington, Renata L. Kucera, Inês S. Albuquerque, Christopher T. Gibson, Alexander Sibley, Ashley D. Slattery, Jonathan A. Campbell, Salah F. K. Alboaiji, Katherine A. Muller, Jason Young, Nick Adamson, Jason R. Gascooke, Deshetti Jampaiah, Ylias M. Sabri, Suresh K. Bhargava, Samuel J. Ippolito, David A. Lewis, Jamie S. Quinton, Amanda V. Ellis, Alexander Johs, Gonçalo J.L. Bernardes and Justin M. Chalke

Gond’s Nagoba Jatara; Performance of Bheati Koriyal

Nagoba Jatara is the biggest and ancient festival of Gonds with full of rituals. Gonds are aboriginal tribes of India who live in the Adilabad district of Telangana State. Amongst the many cultural practices of the Nagoba festival (Serpent God), Bheati Koriyal is an interesting ritual practice in this annual festival, young girls or women who are newly or previously married are introduced to the community members and their God (Nagoba). Then these brides are deemed eligible to worship their supreme God on their own. The present paper aims to understand the ‘Performance of Bheati Koriyal Process. Participant observation and interview methods were used in data collection. The documentation of ritual practices also done during data collection

Cold vapor integrated quartz crystal microbalance (CV-QCM) based detection of mercury ions with gold nanostructures

In this study, we developed a novel method of integrating the well-accepted cold vapor technique with gold nanostructured based quartz crystal microbalance (QCM) devices to selectively detect mercury ions (Hg2+). This method allows for the conversion of aqueous mercury ions into elemental mercury (Hg°) vapor form and thereon use the highly sensitive QCM based mercury vapor sensors to detect the evolved mercury. The method involves reducing mercury chloride (HgCl2) in contaminated water by mixing it with a 2% tin chloride (SnCl2) solution in order to evolve Hg° vapor from the liquid mixture. The selectivity and sensitivity performance of each gold nanostructure, namely, the control Au thin film (Au-ctrl), Au-nanospheres (Au-NS) and Au-nanourchins (Au-NU), towards mercury vapor was evaluated. It was found that Au-NS and Au-NU sensors displayed up to 79% and 243% higher response magnitudes than the Au-ctrl sensor for various concentrations of HgCl2, respectively. All three sensors exhibited repeatable sensing performance when reporting the concentrations from 5 sensing events involving 500 ppb HgCl2 solution with Au-ctrl, Au-NS and Au-NU having the coefficient of variance (CoV) values of ˜5.7, 2.9 and 3.8%, respectively. Moreover, the sensors were observed to operate in the linear region with the mercury ion concentration range calibrated and tested. Importantly, the sensors showed no cross-interference effects when tested toward Hg2+ ions with and without the presence of other metal ions such as lead, cadmium, manganese, iron, and zinc. The results indicate that the CV-QCM technique developed is feasible to be potentially used in real-world mercury monitoring applications