Search

Calcination temperature is a crucial parameter that can be easily controlled to induce a change in material properties. Herein, iron tungstate (FeWO4) was synthesized via a hydrothermal method using iron(II) sulfate heptahydrate and sodium tungstate dihydrate as precursors and calcined at the temperature between 300 oC and 700 oC. With increasing calcination temperature, the saturation magnetization of FeWO4nanoparticles decreased from 6.6 emu/g for FeWO4to 0.4 emu/g for FeWO4_700, whereas their band gaps increased from 1.95 eV for FeWO4to 2.20 eV for FeWO4_700. More crystallinity and crystal defects, and morphological changes at higher calcination temperatures contributed to varying magneto-optical properties of FeWO4nanoparticles.

Elevating the electrocatalytic performance of both cathode and anode catalysts is critical to the advancement and widespread utilization of low-temperature fuel cells. Herein, we report an effective Pt3Ir/Ti0.7W0.3O2catalyst for the oxygen reduction reaction (ORR) and ethanol electro-oxidation reaction (EOR) using a facile reduction process. In terms of the ORR, the Pt3Ir/Ti0.7W0.3O2catalyst shows a specific activity of 0.99 mA cm−2and a mass activity of 0.802 A mgPt−1, which are 6.72- and 7.22-fold improvements compared to the commercial Pt/C catalyst. The result of the 10 000-cycle accelerated durability test (ADT) under an O2atmosphere indicates that the impressive ORR stability of the Pt3Ir/Ti0.7W0.3O2catalyst with a decay of 12.26% in mass activity, against a large decrease of 45.76% for Pt/C (E-TEK). In addition, the Pt3Ir/Ti0.7W0.3O2catalyst exhibits better EOR performance compared to the Pt/C catalyst with a high mass activity (810.03 mA mgPt−1) along with superior CO-tolerant ability and durability. The improved electrocatalytic performance of the Pt3Ir/Ti0.7W0.3O2catalyst is attributed to the beneficial effect of alloying Pt with Ir and the merit of the TiO2-based support along with the synergistic effect between the Pt3Ir alloy and Ti0.7W0.3O2support. These findings can offer a robust catalyst platform for fuel cells, solar cells, and biosensors.

In this work, we prepared an Ir,N-doped TiO2nanomaterial via a facile HNO3-assisted hydrothermal process that was used as an advanced support for nano-sized Pt nanoparticles (NPs) for the formic acid oxidation reaction (FAOR). The physical and electrochemical behaviours of the as-made Pt/Ir,N-doped TiO2catalyst were systemically investigated through X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), field emission scanning electron microscopes coupled with energy dispersive X-ray analysis (FE-SEM/EDX mapping), transmission electron microscopy (TEM), linear sweep voltammetry (LSV), Tafel slope, CO-stripping, and chronoamperometric (CA) test. The Pt NPs (ca. 3 nm) were anchored on the Ir,N-doped TiO2support, being formed by a mixture of rutile and brookite with a particle size of several ten nanometers. Due to the small size and uniform distribution of Pt NPs, the Pt/Ir,N-doped TiO2catalyst had an electrochemical surface area of 79.88 m2g−1, which was greater than that of the commercial Pt/C (77.63 m2g−1). In terms of the FAOR, the Pt/Ir,N-doped TiO2catalyst showed a negative FAOR onset potential, high current density (11.85 mA cm−2), and superior CO-tolerance compared to the commercially available catalyst. Also, the as-made catalyst possessed high electrochemical durability after 3600 s for testing. The enhanced FAOR efficiency was assigned to the formation of a dual-doping effect and strong interplay between Pt and TiO2-based support, which not only improved the electron transfer but also weakened the adsorption of carbonaceous species, thereby boosting the reaction kinetics. This study could open up a facile but effective strategy to promote particular electrochemical applications.

Developing robust catalysts is still challenging for further commercialization of low-temperature fuel cell technologies. In this study, we introduce platinum nanocatalyst loading on Ti0.7Ir0.3O2to assemble a robust Pt/Ti0.7Ir0.3O2catalyst toward the methanol oxidation reaction (MOR) in direct methanol fuel cell systems. These observational results demonstrated that the Pt/Ti0.7Ir0.3O2catalyst is a promising anodic electrocatalyst due to the superior electrocatalytic activity and durability toward MOR, which was exhibited from the onset potential of ∼0.1 V and high current density of ∼21.69 mA/cm2versus that of the state-of-the-art Pt/C (E-TEK) catalyst. We also demonstrated the electronic transfer from the Ti0.7Ir0.3O2catalyst support to Pt NPs resulting in the modified surface electronic structure of Pt NPs, which could be the reason for the high activity and durability of the Pt/Ti0.7Ir0.3O2catalyst. In addition, this approach could supply a promising potential catalyst for fuel cell technology and other applications such as solar cells, biosensors, and water splitting.

The tungsten-modified titanium dioxide, which prepared through the one-pot solvothermal process, exhibited the large specific surface area (~ 202 m2/g) and greater electrical conductivity (~ 0.022 S/cm). Furthermore, for the comparison purpose to find appropriate approach for the synthesis 20 wt. % Pt NPs/Ti0.7W0.3O2 catalyst, the modified chemical reduction utilizing NaBH4 and the rapid microwave-assisted polyol using ethylene glycol were employed without any surfactants or stabilizers. The characterization of Pt-based electrocatalyst was investigated through XRD, SEM-EDX, TEM measurements. As result, the platinum nanocatalyst formation with the face-centered cubic structure (fcc) and the amount loading on Ti0.7W0.3O2 support approximately 20 wt. % of two synthesized methods. However, the diameter size and distribution of Pt nanoforms have clearly classified in two reduction route. For example, the Pt nanocatalyst, which was created by the rapid microwave-assisted polyol at 160 °C for 2 min, exhibited the good distribution on support with ~3 nm diameter. This could be ascribed to the fast and uniform heating of microwave-assisted and moderate reducing possibility of ethylene glycol. These results indicate that the rapid microwave-assisted polyol was an appropriate approach not only for synthesizing 20 wt. % Pt NPs/Ti0.7W0.3O2 catalyst but also for preparing Pt-based electrocatalysts.

Constructing robust support plays a key role in governing the overall catalytic efficiency of metal-based catalysts for electrochemical reactions in sustainable energy-related conversion systems. We herein use a solvothermal method to assemble Ti0.9Ir0.1O2-Activated C composites, exhibiting high surface area and electrical conductivity compared to the pure TiO2material. The material characterisations and electrochemical behaviours of the as-obtained composites are systemically studied by XRD, FE-SEM-EDX mapping, FT-IR, XPS, BET, four-point technique, cyclic voltammetry, etc Notably, the effect of composition on the physical and electrochemical properties of the as-made composites is also explored, which indicated the significant improvement in surface area and electrical conductivity with increasing carbon content, while a reverse trend is observed in the electrochemical durability. Among all studied composites, the Ti0.9Ir0.1O2-Activated C (50:50 wt%) composite can be a suitable support for metal-based catalysts due to its balance in physical properties (electrical conductivity of 1.5 S cm−1and surface area of 152.12 m2g−1) and electrochemical corrosion resistance (high durability after 2000-cycling ADT). This study can open up an efficient strategy to enhance the catalytic performance of electrochemical processes.

Noncarbon materials were recognized as the catalyst support to increase the durability of Proton Exchange Membrane Fuel Cells (PEMFC). One of the most noncarbon materials studied to be an emerging candidate for Pt nanoparticles (Pt NPs) support on the cathode side of PEMFC was M doped-TiO2 due to the highly stable structure of TiO2 and the good conductivity of M-doped TiO2. In this paper, the novel nanostructure Ti0.7Ir0.3O2 was prepared for the first time via low temperature hydrothermal process. The synthesis process for the new nanostructure Ti0.7Ir0.3O2 was studied in detail in this work. The impact of hydrothermal temperature as well as the reaction time on the dominant phase formation is extensively investigated in this work. We found that the Ti0.7Ir0.3O2 nanoparticles exist in both rutile and anatase phase. We found that the Ti0.7Ir0.3O2 nanoparticles with an irregular spherical shape with particle size of approximately 20-30nm with high crystallinity. In addition, we also found that the optimal condition to synthesize the Ti0.7Ir0.3O2 NPs is obtained at 210°C and 10 hours. The result not only introduces a promising catalyst support Ti0.7Ir0.3O2 for much needed fuel cells, but it also open a new material type of Ir doped TiO2.

The materials currently used in proton-exchange membrane fuel cells (PEMFCs) require complex control of operating conditions to make them sufficiently durable to permit commercial deployment. One of the major materials challenges to allow simplification of fuel cell operating strategies is the discovery of catalyst supports that are much more stable to oxidative decomposition than currently used carbon blacks. Here, we report the synthesis and characterization of advanced nanostructure Ti0.7W0.3O2 prepared via a low-temperature solvothermal process without using any surfactants or stabilizers. A promising doped metal oxide is a candidate for such a durable catalyst support. The synthesized nanoparticles were characterized by XRD, TEM measurements. Results show that Ti0.7W0.3O2 exists in a single-phase solid solution with anatase phase of TiO2. Interestingly, the average particles size approximately 5 nm that could be promised to have a large specific surface area, which is an extremely important factor for promising catalyst support. Moreover, Ti0.7W0.3O2 synthesized at 200 °C for 6 hours obtains the smaller particles size without particles agglomeration compared to previous researches. These results open a new approach for synthesis nanostructure Ti0.7W0.3O2 by a solvothermal process for further application as catalyst support in PEMFCs.

The chemokine RANTES (regulated on activation normal T cell expressed and secreted) and its cognate receptor CC chemokine receptor 5 (CCR5) have been implicated in regulating immune cell function. Previously we reported that in T cells, RANTES activation of CCR5 results in Stat1 and Stat3 phosphorylation-activation, leading to Stat1:1 and Stat1:3 dimers that exhibit DNA binding activity and the transcriptional induction of a Stat-inducible gene, c-fos. Given that RANTES and CCR5 have been implicated in T cell activation, we have studied RANTES-induced signaling events in a CCR5-expressing T cell line, PM1. RANTES treatment of PM1 T cells results in the rapid phosphorylation-activation of CCR5, Jak2, and Jak3. RANTES-inducible Jak phosphorylation is insensitive to pertussis toxin inhibition, indicating that RANTES-CCR5-mediated tyrosine phosphorylation events are not coupled directly to Gαiprotein-mediated events. In addition to Jaks, several other proteins are rapidly phosphorylated on tyrosine residues in a RANTES-dependent manner, including the Src kinase p56lck, which associates with Jak3. Additionally our data confirm that the amino-terminally modified RANTES proteins, aminooxypentane-RANTES and Met-RANTES, are agonists for CCR5 and induce early tyrosine phosphorylation events that are indistinguishable from those inducible by RANTES with similar kinetics. Our data also demonstrate that RANTES activates the p38 mitogen-activated protein (MAP) kinase pathway. This is evidenced by the rapid RANTES-dependent phosphorylation and activation of p38 MAP kinase as well as the activation of the downstream effector of p38, MAP kinase-activated protein (MAPKAP) kinase-2. Pharmacological inhibition of RANTES-dependent p38 MAP kinase activation blocks MAPKAP kinase-2 activity. Thus, activation of Jak kinases and p38 MAP kinase by RANTES regulates the engagement of multiple signaling pathways.

Developing a cost‐effective electrocatalyst toward ethanol electrochemical oxidation plays a vital role in large‐scale applications of direct ethanol fuel cells (DEFCs). Herein, a rutile Ti0.9Ir0.1O2‐supported low Pt‐loading catalyst is fabricated using a surfactant‐free one‐pot chemical reduction route at room temperature that not only reduces the amount of the Pt loading but also significantly enhances the CO antipoisoning and electrochemical stability toward ethanol electrochemical oxidation compared with the conventional carbon‐supported Pt electrocatalyst. The rutile Ti0.9Ir0.1O2nanosupport with rod‐like morphology is first prepared via a one‐pot hydrothermal route, and then 15.5 wt% Pt nanoparticles with small size (≈3 nm) are anchored on it by the surfactant‐free chemical reduction process. For ethanol electrochemical oxidation, the rutile Ti0.9Ir0.1O2‐supported Pt catalyst shows a moderate current density (≈13.74 mA cm−2), which is comparable with the 20 wt% Pt/C electrocatalyst, despite its low loading (15.5 wt%). In addition, the rutile Ti0.9Ir0.1O2‐supported low Pt‐loading electrocatalyst demonstrates low onset potential (0.45 V vs normal hydrogen electrode [NHE]), superior CO‐tolerance, and impressive electrochemical stability compared with the carbon‐supported Pt catalyst. These enhancements are ascribable to the inherent durability of the rutile TiO2nanostructure and the synergistic effect between Pt and Ti0.9Ir0.1O2nanosupport. Herein, a rutile Ti0.9Ir0.1O2‐supported low Pt‐loading electrocatalyst is fabricated using a surfactant‐free one‐pot chemical reduction route at room temperature that not only reduces the amount of the Pt loading but also significantly enhances the CO antipoisoning and electrochemical stability toward ethanol electrochemical oxidation compared with the conventional carbon‐supported Pt electrocatalyst.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.