Fe and Co-doped (Ba, Ca)TiO3 Perovskite as Potential Electrocatalysts for Glutamate Sensing

Barium titanate (BaTiO3) and calcium titanate (CaTiO3) are renown perovskite-structured dielectric materials. Nevertheless, utilization of BaTiO3 and CaTiO3 in sensing applications has not been extensive. This study, therefore, aims at examining potential usage of BaTiO3 and CaTiO3 as enzyme-less sensors.  BaTiO3, CaTiO3, Fe-doped BaTiO3, Co-doped BaTiO3, Fe-doped BaTiO3, and Co-doped CaTiO3 (with Fe and Co 5 at%) were synthesized by solution combustion technique, compositionally and microstructurally examined, and tested for their electrocatalytic activities. All powders consisted of submicrometer-sized particles. Measurements of electrocatalytic activities in 0.01 M glutamate solution by cyclic voltammetry were performed. It was found that oxidation peaks occurred at applied voltage close to 0.6 V. Peak currents, which denoted electrocatalytic performance, were prominent in doped powders. Electrocatalytic activities of the powders were discussed with respect to chemical composition, microstructure, and electronic characteristic of the materials

Electrocatalytic Properties of Calcium Titanate, Strontium Titanate, and Strontium Calcium Titanate Powders Synthesized by Solution Combustion Technique

Calcium titanate (CaTiO3), strontium titanate (SrTiO3), and strontium calcium titanate (SrxCa1−xTiO3) are widely recognized and utilized as dielectric materials. Their electrocatalytic properties, however, have not been extensively examined. The aim of this research is to explore the electrocatalytic performance of calcium titanate, strontium titanate, and strontium calcium titanate, as potential sensing materials. Experimental results revealed that CaTiO3, SrTiO3, and Sr0.5Ca0.5TiO3 powders synthesized by the solution combustion technique consisted of submicrometer-sized particles with specific surface areas ranging from 4.19 to 5.98 m2/g. Optical bandgap results indicated that while CaTiO3 and SrTiO3 had bandgap energies close to 3 eV, Sr0.5Ca0.5TiO3 yielded a lower bandgap energy of 2.6 eV. Cyclic voltammetry tests, measured in 0.1 M sodium nitrite, showed oxidation peaks occurring at 0.58 V applied voltage. The highest peak current was observed in Sr0.5Ca0.5TiO3 powder. The superior electrocatalytic performance of Sr0.5Ca0.5TiO3 might be attributed to lower bandgap energy, which consequently facilitates higher electron transfer. Electrocatalytic performance of Sr0.5Ca0.5TiO3 was subsequently reexamined in a wider concentration range of sodium nitrite. The results revealed that the material responded linearly to nitrite solution in the range of 0.1 mM to 0.1 M and exhibited sensitivity ranging from 3.117 to 0.040 μA/mM, in the entire tested nitrite concentrations. The results suggest that Sr0.5Ca0.5TiO3 could also be used for nitrite detection

Electrocatalytic Properties of a BaTiO₃/MWCNT Composite for Citric Acid Detection

Although barium titanate (BaTiO3) shows prominent dielectric properties for fabricating electronic devices, its utilization in electrochemical applications is limited. Thus, this study examined the potential of a BaTiO3-based composite in the detection of a food additive, i.e., citric acid. First, a submicron-scale BaTiO3 powder was synthesized using the solution combustion method. Then, a BaTiO3/multiwalled carbon nanotube (MWCNT) composite was hydrothermally synthesized at BaTiO3:MWCNT mass ratios of 1:1 and 2:1. This composite was used as a working electrode in a nonenzymatic sensor to evaluate its electrocatalytic activity. Cyclic voltammetric measurements revealed that the BaTiO3/MWCNT composite (2:1) exhibited the highest electrocatalytic activity. Reduction reactions were observed at applied voltages of approximately 0.02 and −0.67 V, whereas oxidation reactions were detected at −0.65 and 0.47 V. With acceptable sensitivity, decent selectivity, and fair stability, the BaTiO3/MWCNT composite (2:1) showed good potential for citric acid detection

Fe-Doped CuO/MWCNT as a Sensing Material for Electrochemical Detection of Nitrite

With unique electrical and catalytic properties, CuO has been ubiquitously employed in many applications including electrochemical sensors. Enhanced electrocatalytic performance of CuO can be achieved through doping. This work explored the potential of 3 mol% Fe-doped CuO/multi-walled carbon nanotube (MWCNT) composite for nitrite detection. The undoped CuO and 3 mol% Fe-doped CuO powders, prepared using a solution combustion technique, had average particle sizes lower than 100 nanometres. Particle refinement and enhancement of the specific surface area were observed in 3 mol% Fe-doped CuO. CuO/MWCNT and 3 mol% Fe-doped CuO/MWCNT composites, prepared using the hydrothermal impregnation technique, were tested for their electrocatalytic activities in the presence of nitrite. Cyclic voltammetry results revealed reduction reaction at an applied voltage of approximately −0.4 V. Superior peak currents were evident in the 3 mol% Fe-doped CuO/MWCNT composite. With acceptable sensitivity, limit of detection, selectivity, reusability, and recovery percentage, the 3 mol% Fe-doped CuO/MWCNT composite demonstrated potential capability in the detection of nitrite

Fe-Doped CuO/MWCNT as a Sensing Material for Electrochemical Detection of Nitrite

With unique electrical and catalytic properties, CuO has been ubiquitously employed in many applications including electrochemical sensors. Enhanced electrocatalytic performance of CuO can be achieved through doping. This work explored the potential of 3 mol% Fe-doped CuO/multi-walled carbon nanotube (MWCNT) composite for nitrite detection. The undoped CuO and 3 mol% Fe-doped CuO powders, prepared using a solution combustion technique, had average particle sizes lower than 100 nanometres. Particle refinement and enhancement of the specific surface area were observed in 3 mol% Fe-doped CuO. CuO/MWCNT and 3 mol% Fe-doped CuO/MWCNT composites, prepared using the hydrothermal impregnation technique, were tested for their electrocatalytic activities in the presence of nitrite. Cyclic voltammetry results revealed reduction reaction at an applied voltage of approximately −0.4 V. Superior peak currents were evident in the 3 mol% Fe-doped CuO/MWCNT composite. With acceptable sensitivity, limit of detection, selectivity, reusability, and recovery percentage, the 3 mol% Fe-doped CuO/MWCNT composite demonstrated potential capability in the detection of nitrite