H2O2 rejuvenation-mediated synthesis of stable mixed-morphology Ag3PO4 photocatalysts.

Ag3PO4 photocatalyst has attracted interest of the scientific community in recent times due to its reported high efficiency for water oxidation and dye degradation. However, Ag3PO4 photo-corrodes if electron accepter such as AgNO3 is not used as scavenger. Synthesis of efficient Ag3PO4 followed by a simple protocol for regeneration of the photocatalyst is therefore a prerequisite for practical application. Herein, we present a facile method for the synthesis of a highly efficient Ag3PO4, whose photocatalytic efficiency was demonstrated using 3 different organic dyes: Methylene Blue (MB), Methyl orange (MO) and Rhodamine B (RhB) organic dyes for degradation tests. Approximately, 19 % of Ag3PO4 is converted to Ag0 after 4.30 hours of continuous UV-Vis irradiation in presence of MB organic dye. We have shown that the Ag/Ag3PO4 composite can be rejuvenated by a simple chemical oxidation step after several cycles of photocatalysis tests. At an optimal pH of 6.5, a mixture of cubic, rhombic dodecahedron, nanosphere and nanocrystals morphologies of the photocatalyst was formed. H2O2 served as the chemical oxidant to re-insert the surface metallic Ag into the Ag3PO4 photocatalyst but also as the agent that can control morphology of the regenerated as-prepared photocatalyst without the need for any other morphology controlling Agent (MCA). Surprisingly, the as- regenerated Ag3PO4 was found to have higher photocatalytic reactivity than the freshly made material and superior at least 17 times in comparison with the conventional Degussa TiO2, and some of TiO2 composites tested in this work

Inkjet Printing Infiltration of the Doped Ceria Interlayer in Commercial Anode-Supported SOFCs.

Single-step inkjet printing infiltration with doped ceria Ce0.9Ye0.1O1.95 (YDC) and cobalt oxide (CoxOy) precursor inks was performed in order to modify the properties of the doped ceria interlayer in commercial (50 × 50 × 0.5 mm3 size) anode-supported SOFCs. The penetration of the inks throughout the La0.8Sr0.2Co0.5Fe0.5O3-δ porous cathode to the Gd0.1Ce0.9O2 (GDC) interlayer was achieved by optimisation of the inks' rheology jetting parameters. The low-temperature calcination (750 °C) resulted in densification of the Gd-doped ceria porous interlayer as well as decoration of the cathode scaffold with nanoparticles (~20-50 nm in size). The I-V testing in pure hydrogen showed a maximum power density gain of ~20% at 700 °C and ~97% at 800 °C for the infiltrated cells. The latter effect was largely assigned to the improvement in the interfacial Ohmic resistance due to the densification of the interlayer. The EIS study of the polarisation losses of the reference and infiltrated cells revealed a reduction in the activation polarisations losses at 700 °C due to the nano-decoration of the La0.8Sr0.2Co0.5Fe0.5O3-δ scaffold surface. Such was not the case at 800 °C, where the drop in Ohmic losses was dominant. This work demonstrated that single-step inkjet printing infiltration, a non-disruptive, low-cost technique, can produce significant and scalable performance enhancements in commercial anode-supported SOFCs

Advancing the Use of High-Performance Graphene-Based Multimodal Polymer Nanocomposite at Scale.

The production of an innovative, high-performance graphene-based polymer nanocomposite using cost-effective techniques was pursued in this study. Well-dispersed and uniformly distributed graphene platelets within a polymer matrix, with strong interfacial bonding between the platelets and the matrix, provided an optimal nanocomposite system for industrial interest. This study reports on the reinforcement of high molecular weight multimodal-high-density polyethylene reinforced by a microwave-induced plasma graphene, using melt intercalation. The tailored process included designing a suitable screw configuration, paired with coordinating extruder conditions and blending techniques. This enabled the polymer to sufficiently degrade, predominantly through thermomechanical-degradation, as well as thermo-oxidative degradation, which subsequently created a suitable medium for the graphene sheets to disperse readily and distribute evenly within the polymer matrix. Different microscopy techniques were employed to prove the effectiveness. This was then qualitatively assessed by Raman spectroscopy, X-ray diffraction, rheology, mechanical testing, density measurements, thermal expansion, and thermogravimetric analysis, confirming both the originality as well as the effectiveness of the process

Growth of ultrasmall nanoparticles based on thermodynamic size focusing

Abstract This study presents a new concept to synthesize quantum dots or nanoparticles with smaller size (\2 nm) based on the thermodynamic size focusing. Conventionally, control over crystal size is achieved by interrupting crystal growth and/or limiting the reaction rate at lower temperature. Alternatively, we synthesized ultrasmall nanoparticles via a simple thermal quenching-isothermal annealing process called the thermal size focusing. This approach, avoiding the difficulty of controlling the rapid nanoparticles' growth in the interruption method or long synthesis time in the low-temperature process, provides an efficient way for obtaining ultrasmall nanoparticles

Electrolytic preparation and characterization of VCr alloys in molten salt from vanadium slag

Vanadium slag contains several critical elements like V, Ti, Cr, Fe and Mn. In our previous work, V and Cr have been enriched by selective chlorination, increasing from 10.05% to 14.95% and 5.84%-8.69% separately. V and Cr still maintain the trivalence state in molten salt. In the current work, the electrodeposition behaviors of V3+ and Cr3+ in NaCl-KCl molten salt at 800 degrees C were investigated using cyclic voltammetry (CV) and square wave voltammetry (SWV) with a tungsten electrode. It was found that the reduction processes of V3+ and Cr3+ consist of two steps, M3+/M2+, M2+/M. The diffusion coefficients of V3+ and Cr3+ in NaCl-KCl molten salt were measured by CV. The effect of VCl3/CrCl3 mass ratio on VCr alloy was investigated by a two-electrode under constant voltage. Pure Cr can be obtained at 2.8 V in the NaCl-KCl molten salt, while VCr alloy (3.71 mass % V-94.28 mass% Cr-2.01 mass % O) was obtained when electrolysis voltage was controlled to 2.8 V at 800 degrees C. The composition of VCr alloy can be designed by changing the molten salt composition. This method can be applied for direct preparation of VCr alloy from vanadium slag, thus offering the use of low cost raw materials with direct environmental benefits. (C) 2019 Published by Elsevier B.V

Research data for "Charge-Dependent Crossover in Aqueous Organic Redox Flow Batteries Revealed Using On-Line NMR Spectroscopy"

All raw data 1H NMR data (including calibration experiments, pseudo-2d crossover data, t1ir experiments), electrochemical data, images and MATLAB code associated with the publication 'Charge-Dependent Crossover in Aqueous Organic Redox Flow Batteries Revealed Using On-Line NMR Spectroscopy'. 'README' files detail where and how the data was used in the publication. Abstract of related publication: Aqueous organic redox-flow batteries have emerged as promising candidates for the low-cost long-duration energy storage solution that is required to integrate renewable energy into the electricity grid. However, their widescale deployment is currently limited by crossover of redox-active material through the separator membrane, which leads to capacity decay over time. Traditional membrane permeability measurements only account for diffusional crossover, and do not capture all contributions to membrane transport in working batteries, including migration. Here we present a new method for characterising crossover in operating aqueous organic redox-flow batteries, using on-line 1H NMR analysis. Using the 2,6-dihydroxyantharquinone/ferrocyanide battery as a model, we observed a doubling of 2,6-dihydroxyantharquinone crossover rates during battery charging, which we believe is due to additional transport by migration. This method can distinguish different transport mechanisms during battery charging and will aid the optimisation of charging protocols and membrane design in the future.T. Kress was also supported by an Ernest Oppenheimer studentship

Janus nanostructures for heterogeneous photocatalysis

Water treatment, the hydrogen evolution reaction, and carbon capture are examples of the potential applications for solar photocatalysis. This has led to significant effort in the search for suitable heterogeneous catalysts. However, materials developed to-date often suffer from disadvantages such as charge recombination, low quantum efficiency, chemical instability, and poor economy of production/operation. These factors have made it difficult for the technology to develop beyond laboratory demonstrations. A potential solution to the problem lies with the appropriate design of the catalyst itself, particularly with respect to particle morphology. This review aims to highlight recent efforts directed towards the development and application of an anisotropic, bi-phasic heterodimer, or "Janus" catalyst. While the topic is in its relative infancy, it has been shown that a Janus morphology can improve catalyst performance by almost an order of magnitude. Hence, a systematic review has been undertaken to highlight and assess recent advances in this field. The review begins with the fundamentals of heterogeneous photocatalysis and proceeds to classify modern catalysts, including Janus particles. This is followed by a detailed description of the relevant studies involving Janus morphology and their demonstrated photocatalytic applications. Finally, an overview of the current challenges and future prospects is discussed along with a summary of the key highlights. It is observed that a Janus morphology can impart several intriguing advantages such as amplification of electric near-field and efficient charge separation. In order to unlock the full potential of Janus photocatalyst, further research in this direction is warranted. Published by AIP Publishing

Atmospheric pressure plasma engineered superhydrophilic CuO surfaces with enhanced catalytic activities

Cupric oxide (CuO) thin film has found widespread application as a low-cost, earth-abundant material for electro and photo catalytic applications. High surface wettability is a key factor to achieve enhanced efficiency in these catalytic applications. Here, we report a fast and environment friendly route to fabricate super hydrophilic CuO thin films using a low power (5 to 10 Watts) atmospheric pressure plasma jet (APPJ). With APPJ treatment for 5 minutes, the CuO surface transforms from hydrophobic to super-hydrophilic with threefold increase in catalytic activity. The electrodes were extensively characterized using various bulk and surface-sensitive techniques. APPJ introduces anisotropy in the crystal structure and creates unique three-dimensional surface morphology with distinct surface chemical and electronic features. Interestingly, presence of oxygen in the plasma was found to be critical for the enhanced activities and the activity decreased when the functionalised with nitrogen plasma. Oxygen plasma functionalisation of CuO electrodes resulted in a 130 mV reduction in the onset potential for oxygen evolution reaction along with enhanced current density ,10 mA cm-2 against 3 mA cm-2 at 1 V vs Saturated Calomel Electrode in 0.1M KOH without iR compensation. Importantly, without introducing any external dopants the work function could be decreased by 80mV. Moreover, the treated films exhibited a higher rate of photo degradation (0.0283 min-1 compared to 0.0139 min-1) of Methylene Blue and phenol indicating efficient charge separation. This work presents the potential of APPJ functionalisation of CuO surface to boost the activity of other thin film catalyst materials and solutions processed systems