Catalysts are required for both the oxidation of water and the reduction of oxygen. Blended oxides of Ir and Ru are superior for water oxidation whereas mixtures of Pt and Ir perform better when both oxidation of water and reduction of oxygen are required on the same electrode. A strategy for rationing these elements is explored by the formation of a thin film using a dry, flame process. IrxPt1-xO2-y and IrxRu1-xO2-y were both deposited from the vapor phase, as thin films, onto substrates of glassy carbon, polypropylene, and quartz. Elemental analysis of the Ir-Pt electrode suggests a stoichiometry of Ir0.56Pt0.44O2-y. Bulk diffraction of the film shows two separate phases consisting of Pt metal and IrO2. The sample showed signs of spallation after 10 cycles when scanned between 1.2 and 1.7 V. A weak oxygen evolution current of 0.8–0.4 mA/mg was measured at 1.6 V. Elemental analysis of the Ru-Ir film suggests a ratio of Ru0.41Ir0.59O2-y. Phases of a homogeneous solid-solution of IrO2 and RuO2 and to a lesser extent Ru metal are shown by bulk X-ray diffraction. An exceptional oxygen evolution current of 25–40 mA/cm2 was observed for the Ru0.41Ir0.59O2-y sample corresponding to a normalized mass activity of 400 mA/mg.

No abstract

No abstract

No abstract

No abstract

a b s t r a c tA porous tungsten oxide (WO 3 ) NO 2 sensor was developed by a one-step flame based process called Reactive Spray Deposition Technology (RSDT). This nano-crystalline WO 3 film was deposited directly on gold interdigitated electrodes. The sensing characteristics of this NO 2 sensor was measured at the parts per million (ppm) level, (0.17-5 ppm in air) at 300 • C. The sensors showed a relatively fast response time (∼7s) and recovery time (∼5 min), respectively. The stability of the sensor was evaluated for 300 h in 0.5 ppm NO 2 at 300 • C in (2000 response-recovery cycles). The sensor was stable up to 6 days (∼150 h) of continuous operation and degraded between 150-300 h. The morphology and surface properties of the WO 3 film were investigated with XRD, Raman spectroscopy, BET, SEM, TEM, and HRTEM.

Thin films of RuxIr1-xO2-y have been deposited by a dry combustion process directly onto polypropylene and quartz coupons for characterization and on a gold disk to evaluate the electrochemical suitability as an oxygen evolution electrode. Compositional analysis on the oxygen evolution catalyst suggests a chemical formula of Ru0.41Ir0.59O2-y. Bulk diffraction of the thin film Ru0.41Ir0.59O2-y suggests phases of IrO2 and RuO2 and to a lesser extent Ru metal with no Ir metal. The photoelectron emission spectrum of the film suggests that Ru exists primarily in the oxidized state. The integrated area of the Ir metal peaks is an order of magnitude larger than the RuO2 peaks and 6 times larger than the corresponding oxide suggesting a surface enriched in Ir metal in contrast to the diffraction findings. An exceptional oxygen evolution current of 25-40 mA/cm2 was observed for a Ru0.41Ir0.59O2-y thin film supported on a gold rotating disk electrode in a 0.5 M H2SO4 electrolyte measured at a potential of 1.6 V. The corresponding mass activity of the electrode is exceptionally high at 400 mA/mg of Ru0.5Ir0.5O2 compared to 50-75 mA/mg of Ru0.5Ir0.5O2 from the literature.

not Available.