Effect of Partial Replacement of Pt-Based Catalysts with Fe- and Co-for Oxygen Evolution Reaction in Pem Water Electrolysis: A Combined Theoretical and Experimental Study

The adsorption of Ptn (n = 1−4) clusters and co-adsorption of Ptn-Co and Ptn-Fe on the defect-free anatase TiO2(101) surface have been studied theoretically at density functional theory (DFT) level. The most stable configurations are observed due to Pt2 and Pt3-clusters adsorbed on the titania surface. The electronic structure analyses show that the Fermi level is pinned by Pt, which reduces the band gap from ~3 eV of the clean surface to significantly less than 1 eV for Pt3. For the co-adsorption of Fe-Pt and Co-Pt, there is a strong bond formation of Fe and Co with the surface O and Ti atoms. In both cases, Fe and Co stay far away from the Pt atom. Due to strong interaction of adsorbed elements with Ti, the co-adsorption energy is larger than the corresponding Pt3 adsorption energy. The higher stability of the co-adsorption of Fe-Ptn compared to the Co-Ptn is in agreement with the electrochemical experimental results which confirm that Fe-containing catalysts deposited on titanium dioxide support (Ebonex) will be higher efficient than Co-containing ones toward oxygen evolution in proton-exchange membrane water electrolysis. The observed effect can be explained with formation of solid solution between the metallic components and a realization of synergetic effect

Influence of failure modes on PEFC stack and single cell performance and durability

The paper reports on the influence of low humidity, short-circuiting, hydrogen starvation and open circuit potential on the performance and service life of 11 kW PEFC stack and 25 cm2 single cell. The failure modes in PEFC stack were caused by series of laboratory and software shortcomings during the tests, while tests in a single PEFC were performed for comparison purpose. Due to the impossibility to predict the influence of the failure modes on PEFC stack performance and durability based solely on the results obtained in a single PEFC demonstrated in the paper and having in mind the cost of a high power PEFC stack there is a lack of systematic knowledge in the field. The failure modes’ influence was investigated in detail on the performance of the overall PEFC stack, individually on each membrane electrode assembly (MEA) in the stack and on the single PEFC. The reasons for MEAs failures were explained and recommendations for PEFC stack rehabilitation were given. By analyzing the reasons and shortcomings causing the failure modes the paper also provides information on some specifics in coupling and communication between some conditioning and testing devices.JRC.F.2-Cleaner energ

Influence of sputtering pressure on surface structure and oxygen reduction reaction catalytic activity of thin platinum films

The work presents a study on the influence of the sputtering pressure on the surface structure and morphology of low Pt loaded electrodes and their electrochemical behaviour toward oxygen reduction reaction (orr) in sulphuric acid solution and polymer electrolytemembrane(Nafion 117). Ptwasdeposited as thin film upon hydrophobic carbon paper substrates at sputtering pressure varied in the range 2–13 Pa. The test samples are analysed by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The catalytic activity is assessed by applying the methods of linear sweep voltammetry (LSV) on rotating disc electrode (RDE) and cyclic voltammetry (CV). The results obtained show strong influence of the sputtering pressure on the surface structure and crystal orientation which in turn, affects the orr efficiency. The best electrode performance in both electrolytes used is obtained for the Pt film deposited at pressure of 9 Pa. The results obtained in Nafion 117 show that catalyst utilisation in this electrode exceeds significantly the one for a commercial ELAT electrode at the same operation conditions. The research demonstrated that by simple variations in the sputter regime it is possible to optimise the catalysts morphology in order to increase the catalytic activity toward the electrochemical reaction of interest at the same time controlling precisely the required precious metal loading.JRC.F.2-Cleaner energ

Experimental Validation of the "EasyTest Cell" Operational Principle for Autonomous MEA Characterization

The paper presents the experimental validation of the "EasyTest Cell" operational principle via comparative electrochemical tests on MEAs carried out in three types of electrochemical hydrogen energy conversion (EHEC) testing cells: conventional polymer electrolyte membrane fuel cells (PEMFC) and polymer electrolyte membrane water electrolyzers (PEMWE), properly equipped with all the required auxiliaries (products conditioning and supplying, reagents removal, etc.) and the simple, autonomous EasyTest Cell. Along with EasyTest Cell validation and demonstration of its advantages, the influence of argon pressure during sputtering on the electrode characteristics, including gas diffusion limitations was investigated. The electrodes under investigation were magnetron sputtered C/Ti/IrOx (IrOx loading in the range 0.12-0.4 mg.cm-2), C/Ti/IrOx/Pt/IrOx (IrOx 0.08/Pt 0.06/IrOx 0.08 mg.cm-2), sputtered at various argon pressure C/Ti/Pt (0.15 and 0.25 mg.cm-2), and commercial ELAT electrode (V.21, Lot # MB030105- 1, Pt loading 0.5 mg cm-2, E-TEK). The results obtained proved the reliability, simplicity (running-periphery-free) and broadened experimental possibilities of EasyTest Cell over PEMFC and PEMWE single cell testing. Thus, significant cost reduction and resource saving in R&D laboratory can be achieved. Moreover, validation of EasyTest Cell contributes not only to testing facilitations, but potentially to standardization of MEA testing since it gives possibilities for precise control and more uniform distribution of the working parameters applied to the testing object, which are both compulsory for performance comparison and qualifying.JRC.F.2-Cleaner energ

За кадры. 1977. № 74 (2069)

С праздником, энергетики! / А. Гурченок, Н. ПоповРапортует ЭЭФ / Н. Г. ВолковТЭФ к празднику / А. ЛяликовЗа строкой решения съезда / А. С. ЗаворинЗа эффективность партийного руководства / М. ИвановаПомощь молодым коллегам / В. Н. БеломестныхНакануне сессииДосуг - дело серьезное / Н. БедаревВместе работа спорится. Закон и мы / С. ГореловНужен контакт. Закон и мы / В. КарпачевПрава молодого специалиста. Закон и мы / З. Кошк

Optimization of Platinium/Iridium Ratio in Thin Sputtered Films for PEMFC Cathodes

The paper presents an investigation on the electrocatalytic activity of co-sputtered PtIr thin films towards the ORR. The catalyst composition was controlled by varying the sputtering power of the Ir target in the range 20 - 100 W at constant power of 100 W for the Pt target. The films were analyzed applying SEM, XRD, EDX, XPS (physical characterization); stationary and quasi-stationary polarization curves, cyclic voltammetry and ac impedance ("in situ" tests performed in single PEMFC). The influence of the Pt/Ir ratio on the atomic interaction, morphology, and the resulting electrocatalytic activity was studied in detail. The individual contribution of the film morphology and the Pt/Ir electrocatalytic synergism to the electrode performance was evaluated. The optimal balance between the favourable effect of Ir addition and the lost of active surface sites due to substitution of Pt for Ir was established.JRC.F.2-Cleaner energ