Testing Novel Water Oxidation Catalysts for Solar Fuels Production by Carminna Ottone & Simelys Hernández & Marco Armandi & Barbara Bonelli

Author:Carminna Ottone & Simelys Hernández & Marco Armandi & Barbara Bonelli
Language: eng
Format: epub
ISBN: 9783030127121
Publisher: Springer International Publishing

4.3 Description of the Catalytic Activity Measurements

Two methods have been adopted for measuring the catalytic activity. In one set of experiments, close batch reactors were used in the absence of any stripping gas, so to measure the concentration of DO, hereafter denoted as , by means of a Clark electrode. A small reactor (20 ml) was used to minimize headspace volume. Reactant concentrations and WOCs amount (mg/l) were the same of BR experiments reported below. Also in this case, any O2 present was previously removed by flowing Ar through the liquid phase, under dark conditions before measurements. After sealing the reactor, the stirred solution was illuminated, and O2 production rate was measured by the slope of the linear portion of DO curves [dDO/dt]0.

Most measurements have been run in the BR, using the lab-made equipment shown in Fig. 4.4. In a typical test, the reactor was filled with 130 ml of a solution containing 10 mM buffer phosphate (NaPi) (2 mM NaH2PO4 plus 8 mM Na2HPO4, starting pH = 7.5); 250 mg Na2SO4; 150 mg Na2S2O8 and 45 mg [Ru(bpy)3]Cl2. Then, a specific amount of WOC (in the range of 10–100 mg), degassed at 150 °C for 3 h under vacuum, was introduced into the reactor, then hermetically closed. Pressure and temperature were maintained at 1.01 bar and 20 °C, respectively. Prior to each measurement, O2 was removed by flowing Ar through the liquid phase, under dark conditions. Then, the reactor was illuminated with simulated solar light (100 mW/cm2, LIFI STA-40 model plasma lamp by Luxim). In order to decrease the photon flux, different metallic filters (FSQ-ND01, FSQ-ND 02, FSQ-ND04, Newport) were used to reduce the light intensity. The area illuminated was constant for all the measurements. The irradiance was measured with a Delta Ohm model HD2102.1 photo-radiometer.

Fig. 4.4Picture of the lab-made bubbling reactor system [6]

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