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Proton Exchange Membrane Water Electrolysis
Published in Lei Zhang, Hongbin Zhao, David P. Wilkinson, Xueliang Sun, Jiujun Zhang, Electrochemical Water Electrolysis, 2020
Zhao Jin, Shuai Hou, Zhaoyan Luo, Rongpeng Ma, Yang Li, Yibo Wang, Junjie Ge, Changpeng Liu, Wei Xing
Among the noble metal oxide electrocatalysts, only iridium oxide materials are regarded as promising OER electrocatalysts, because these catalysts exhibit relatively low redox potentials and high operating stability. Platinum, the best catalyst for the oxygen reduction reaction (ORR), has poor performance for the OER, and ruthenium possesses the best catalyst for the OER, but exhibits poor catalytic stability for the oxygen evolution reaction in acidic media. The RuO2 is highly unstable in acidic electrolytes under high operating potential because it will be oxidized to form RuO4 and dissolved in acidic solution.
Corrosion monitoring at the interface using sensors and advanced sensing materials: methods, challenges and opportunities
Published in Corrosion Engineering, Science and Technology, 2023
Vinooth Rajendran, Anil Prathuru, Carlos Fernandez, Nadimul Haque Faisal
Du et al. [247] initiated the non-destructive method of chloride and pH sensors combination to evaluate the chloride ions concentration and pH level at the interface between concrete and steel. The Ag/AgCl electrode prepared by electrochemical anodisation worked as a chloride sensor, and Ir/IrO2 electrode prepared by thermal oxidation in carbonate served as a pH sensor (shown in Figure [29]) and combinations of sensors were designed with epoxy at the interface to prevent the short circuit, and it was embedded in concrete close to the interface of steel. It is well known that Ag/AgCl has the advantage of good stability, small in size and easy fabrication. Compared to the other metal oxide electrodes, iridium oxide shows better stability in a wide range of pH, higher resolution and quick response time even in high pressure and temperature conditions. In their investigation by Du et al. [247], sensor embedded concrete block was immersed for different time periods in the 3.5% NaCl solution to analyse the measuring effect of sensors. The Ag/AgCl electrode measured the potential change based on chloride ions concentration very fast and stable. The sensor measured the maximum level of chloride ion concentration at an interface after 12 days of immersion, followed by small fluctuations in chloride concentration. Initially, the chloride ions concentration difference between the interface and outer surface was large, which led to quick diffusion. The Ir/IrO2 electrode (which served as a pH sensor) measured the values with stability. Results showed that initial pH decreased quickly owing to the diffusion of H+ and OH− happened fast for neutralisation. Overall, the sensor-based measurements (indicating chloride and pH changes) at the interface showed the corrosion behaviour of the reinforced steel [247]. The combination of two sensors (chloride and pH) showed a better measurement of the interface conditions with stability and fast response time. However, owing to the sensor measurement probes being in one place, the sensor measures conditions locally.