Tailoring the microstructure of BiVO4 sensing electrode by nanoparticle decoration and its effect on hazardous NH3 sensing.

Real-time monitoring and quantification of exhaust pollutants is crucial but is troublesome because of extremely harsh thermochemical conditions, and in this regard mixed-potential sensing technology can be a realistic solution. In this study, BiVO4 nanoparticles are decorated onto the preformed porous sensing electrode (SE) backbone by homogeneous infiltration process to improve the sensing performance in mixed-potential sensor. The influence of nanoparticle decoration on phase composition, microstructure and sensing performance are analyzed by physical and electrochemical techniques. Corresponding results indicate that the microstructure tailoring enhances the sensor performance, by extending the triple phase boundary (TPB) and surface area of SE itself. The sensitivity (-119.47 mV/decade) and response time (20 s) of i-BVO SE-based sensor at 600 â„ƒ are 20 % higher and 8 s faster than bare BiVO4 SE-based sensor (99.24 mV/decade and 28 s). Additionally, the i-BVOǀYSZǀPt cell exhibits good selectivity and cross-sensitivity toward NH3 without any dependency on oxygen partial pressure (pO2). The fabricated sensor is also found stable towards cyclic and long-term operations. Electrochemical Impendence Spectroscopy (EIS) and DC polarization studies were performed to confirm the mixed-potential behavior. Conclusively, the superior sensing performance of i-BVO SE compared to various oxide based SEs highlights its suitability for mixed-potential NH3 sensing.

Oxygen nonstoichiometry and thermodynamic quantities of Gd and Cu doped misfit-layered calcium cobaltites.

Hyperstoichiometric (p-type) misfit-layered calcium cobaltites have been studied as components in various high-temperature electrochemical devices. Multiple studies have reported their applications or physical properties, but systematic studies on their defect structures and thermodynamic quantities are still insufficient. In this study, the oxygen nonstoichiometry and the electrical conductivity of Gd-Cu co-doped misfit cobalt oxide were measured as functions of temperature and oxygen partial pressure, along with thermodynamic quantities. The behavior of oxygen nonstoichiometry could not be explained by a defect structure assuming the ideal solution, as it showed a positive deviation in Raoult's law. The redesigned nonideal proposed defect structure, considering that the deviation originated from the high concentration of degenerate holes, could describe the oxygen nonstoichiometry precisely; and in this process, the values of , , Nv, , γh, and were quantitatively extracted. These values were compared with those obtained for the undoped system. The total electrical conductivity was measured using a dense specimen obtained via spark plasma sintering, and the anisotropic nature of the material was confirmed.