Facile synthesis of a porous 3D g-C3N4 photocatalyst for the degradation of organics in shale gas brines

Treatment and subsequent re-use of wastewater from shale gas extraction is a feasible strategy to ensure sustainability and reduce the environmental impact of the process. Here we demonstrate the photocatalytic benefits of improved three-dimensional graphitic carbon nitride (3D g-C3N4) during the degradation of organic contaminants. We show that precursor ratio (melamine to cyanuric acid) affects both the properties of 3D g-C3N4 as well as catalytic performance. When optimized, 3D g-C3N4 displayed the highest organics removal rate in brine-free solutions, achieving 99% conversion within 240 min. Significantly, the 3D g-C3N4 materials improved photocatalytic activity even in simulated shale gas brine solutions

Microwave synthesis of ZnIn2S4/WS2 composites for photocatalytic hydrogen production and hexavalent chromium reduction

A rapid microwave synthesis route for the fabrication of ZnIn2S4 powder and ZnIn2S4/WS2 composites is presented. Firstly, the effects of different sulfur sources – thioacetamide and L-cysteine – on the physicochemical properties and photocatalytic H2 production of the synthesized ZnIn2S4 were investigated. It was found that well-defined flower-like ZnIn2S4 microspheres obtained from L-cysteine facilitated a relatively higher H2 production rate. Then, different loadings of WS2 were introduced into the well-defined flower-like ZnIn2S4 microspheres aiming to improve its photocatalytic H2 production. Compared to pure ZnIn2S4 and WS2, all ZnIn2S4/WS2 composite photocatalysts exhibited enhanced photocatalytic H2 production in the presence of Na2S/Na2SO3 as sacrificial reagents under UV-visible irradiation, where the ZnIn2S4/WS2-40% wt composite had the highest photocatalytic activity. For this material, 293.3 and 76.6 μmol h−1 g−1 of H2 gas were produced under UV-visible and visible light irradiation, respectively. In addition, the photoreduction activity of hexavalent chromium (Cr(VI)) by ZnIn2S4/WS2-40% wt was also investigated under visible light irradiation and it was observed that 98.5% of Cr(VI) was reduced within 90 min at pH 4

Enhanced visible-light-driven photocatalytic H2 production and Cr(vi) reduction of a ZnIn2S4/MoS2 heterojunction synthesized by the biomolecule-assisted microwave heating method

In this work, the biomolecule-assisted microwave heating synthesis of ZnIn2S4, along with the ZnIn2S4/MoS2 composites and their photocatalytic applications, were studied. Well-defined flower-like ZnIn2S4 microspheres synthesized at microwave heating time of 1 h provided the highest surface area and total pore volume, which offered the highest H2 production rate (111.6 μmol h−1 g−1). Different amounts of MoS2 were loaded into the ZnIn2S4 microspheres to form ZnIn2S4/MoS2 composites aiming to improve the H2 production rate. Among the fabricated ZnIn2S4/MoS2 composites, the ZnIn2S4/MoS2-40% wt composite exhibited the highest H2 production rate (200.1 μmol h−1 g−1) under UV-visible light irradiation. In addition, for the first time, this composite was applied for the photoreduction reaction of Cr(VI) ion under visible light irradiation. It provided higher photoreduction efficiency than the single components, where the efficiency was improved in the acidic solutions over the levels recorded in the basic solution. The charge transfer pathway and photocatalytic mechanisms of the ZnIn2S4/MoS2-40% wt photocatalyst have been proposed based on the results obtained from UV-visible diffuse reflectance spectroscopy, photoluminescence spectroscopy, electrochemical impedance spectroscopy, Mott–Schottky measurements and the silver photo-deposition experiment

Effect of the preparation method of LaSrCoFeOx perovskites on the activity of N2O decomposition

N2O remains a major greenhouse gas and contributor to global warming, therefore developing a catalyst that can decompose N2O at low temperatures is of global importance. We have investigated the use of LaSrCoFeOx perovskites for N2O decomposition and the effect of surface area, A and B site elements, Co–O bond strength, redox capabilities and oxygen mobility have been studied. It was found that by using a citric acid preparation method, perovskites with strong redox capabilities and weak Co–O bonds can be formed at relatively low calcination temperatures (550 °C) resulting in highly active catalysts. The enhanced activity is related to the presence of highly mobile oxygen species. Oxygen recombination on the catalyst surface is understood to be a prominent rate limiting step for N2O decomposition. Here the reduced strength of Co–O bonds and mobile lattice oxygen species suggest that the surface oxygen species have enhanced mobility, aiding recombination, and subsequent regeneration of the active sites. La0.75Sr0.25Co0.81Fe0.19Ox prepared by citric acid method converted 50% of the N2O in the feed (T50) at 448 °C

Lowering the operating temperature of perovskite catalysts for N2O decomposition through control of preparation methods

Discovering catalysts that can decompose N2O at low temperatures represents a major challenge in modern catalysis. The effect of preparative route on N2O-decomposition activity has been examined for a PrBaCoO3 perovskite catalyst. Initially, a citric acid preparation was utilised where the A site ratio was altered in order to increase phase purity. Comparable compositions were then prepared by an oxalic acid precipitation method and by a supercritical anti-solvent technique to produce perovskites with a higher surface area (> 30 m2g-1). By altering the A site ratios it was possible to reduce the temperature required to produce a pure phase perovskite whilst maintaining a higher-surface area. The use of the different preparation methods resulted in perovskites with varying properties, as determined by N2 adsorption, XPS and O2-TPD. This work confirms the importance of lattice oxygen species that have high oxygen mobility for enhanced decomposition of N2O, as oxygen recombination is considered the rate-limiting step. Here, the formation of molecular oxygen is limited by surface adsorbed O species being within a distance at which oxygen recombination is possible. The most active PrBaCo-based catalyst did not have the highest percentage of lattice oxygen as shown by XPS, however, the catalytic activity could be correlated to the mobile oxygen species and high surface area. The PrBaCo-based catalyst prepared by supercritical anti-solvent converted 50 % of the N2O present in the feed (T50) at 410 °C, which represents a significant improvement over reported catalytic performance measured under similar conditions

Deactivation Behavior of Supported Gold Palladium Nanoalloy Catalysts during the Selective Oxidation of Benzyl Alcohol in a Micropacked Bed Reactor

Highly active, supported Au–Pd catalysts have been tested for catalyzing benzyl alcohol oxidation in a silicon-glass micropacked bed reactor. The effects of Au–Pd composition and anion content during catalyst preparation on catalyst deactivation were studied, and a relationship between the deactivation rate and the amount of Cl– and Au used in the catalyst formulation was found. While Au aids in enhancing the selectivity to the desired product and the Cl– ions help the formation of uniform 1–2 nm nanoparticles, higher amounts of Au and Cl– become detrimental to the catalyst stability once a certain amount is exceeded. Loss of small (1–2 nm) metal nanoparticles was evident in all catalysts studied, accompanied by agglomeration and the formation of larger >10 nm particles. A secondary deactivation mechanism characterized by the formation of an amorphous surface film was observed via transmission electron microscopy in catalysts with high Cl– and Au and was associated with the detection of carbon species on the catalyst surface using Raman spectroscopy

Investigating periodic table interpolation for the rational design of nanoalloy catalysts for green hydrogen production from ammonia decomposition

Developing highly active catalysts for the decomposition of ammonia to produce hydrogen is an important goal in the context of renewable energy. Allied with this is a need for identification strategies to efficiently design novel catalysts integral to ensuring rapid progress in this research field. We investigated the efficacy of N–binding energy and periodic table interpolation to predict active bimetallic nanoparticle catalysts. Supported iron-platinum and iron-palladium were identified and experimentally shown to be more active than their monometallic analogues. Atomic resolution electron microscopy indicated that the most active catalyst (5 wt% Fe80Pt20/γ-Al2O3) was principally formed of alloyed nanoparticles. It restructured during testing, yet no activity loss was noted at 20 h time-on-line. While these findings show that periodic table interpolation may be a viable tool for identifying active combinations of metals, the activity of the catalysts in the current work were not able to outperform the Ru/Al2O3 benchmark. Further catalyst optimization or refinement of reaction descriptors may facilitate the development of catalysts with higher intrinsic activity than the current state-of-the-art catalysts

Sulfur promotion in Au/C catalyzed acetylene hydrochlorination

The formation of highly active and stable acetylene hydrochlorination catalysts is of great industrial importance. The successful replacement of the highly toxic mercuric chloride catalyst with gold has led to a flurry of research in this area. One key aspect, which led to the commercialization of the gold catalyst is the use of thiosulphate as a stabilizing ligand. This study investigates the use of a range of sulfur containing compounds as promoters for production of highly active Au/C catalysts. Promotion is observed across a range of metal sulfates, non‐metal sulfates, and sulfuric acid treatments. This observed enhancement can be optimized by careful consideration of either pre‐ or post‐treatments, concentration of dopants used, and modification of washing steps. Pre‐treatment of the carbon support with sulfuric acid (0.76 m) resulted in the most active Au/C in this series with an acetylene conversion of ≈70% at 200 °C

Generating dialogical practices in mental health : experiences from southern Norway, 1998-2008

Published version of an article in the journal: Administration and Policy in Mental Health and Mental Health Services Research. Also available from the publisher at: http://dx.doi.org/10.1007/s10488-013-0479-3In Norway and many other countries, political guidelines prescribe the development of mental health strategies with both a service user's perspective and a treatment system established by the local authority. The development of new strategies frequently involves challenges regarding procedures and treatment as well as a view of knowledge and humanity. Dialogical practices might provide a solution for these challenges not only because of its procedures but also due to its attitudes toward service users. The aim is to explore the implementation of three dialogical practice programs in Southern Norway from 1998 to 2008 and to critically analyze and discuss the authors' experiences during the implementation process. Three different programs of dialogical practices were initiated, established, and evaluated within the framework of participatory action research. Sustainable changes succeed individually and organizationally when all participants engage as partners during the implementation of new mental health practices. Generating dialogic practice requires shared understanding of the Open Dialogue Approach (ODA) and collaboration between professional networks and among the leaders. Developing a collaboration area that includes service users in all stages of the projects was one of the essential implementation factors. Other factors involved a common vision of ODA by the leaders and the actors, similar experiences, and a culture of collaboration. However, ODA challenged traditional medical therapy and encountered obstacles to collaboration. Perhaps the best way of surmounting those obstacles is to practice ODA itself during the implementation process

Soft power and soft disempowerment: Qatar, global sport and football’s 2022 World Cup finals

This paper examines the critical role of global sport within Qatar’s international strategy, most notably through the successful bid to stage the 2022 football World Cup. Our discussion draws particularly on interviews with key stakeholders in the Qatari sport system, as well as fieldwork in Qatar and the analysis of relevant documents and secondary materials. The paper is separated into five main parts. First, we set out our theoretical framework, which draws on the concepts of globalization and soft power; to assist in the analysis of Qatar’s engagement with global sport, we introduce the two further concepts of ‘glocal consciousness’ and ‘soft disempowerment’. Second, we provide the reader with background information on Qatar and Qatari sport. Third, we discuss three key themes that emerged mainly from our interviews on Qatar and global sport: exhibiting Qatar’s supremacies as a microstate; the pursuit of peace, security and integrity; and confronting national health crises. Fourth, we explore issues of soft disempowerment and reputational risk with regard to these three themes and, in particular, critical international comment surrounding Qatar’s hosting of the 2022 World Cup. Fifth, we conclude by arguing that Qatar’s soft disempowerment, although damaging in the short term, leaves the door open for the state to respond in a positive manner, regenerating its soft power capabilities in the process