CO2 sensing properties and mechanism of PrFeO3 and NdFeO3 thick film sensor

LPG Sensing Study of Calcium-Doped Praseodymium Orthoferrite Nanomaterial

Liquefied petroleum gas (LPG) is a modern fuel for kitchens, vehicles, and industry. Leakage of LPG is extremely fatal for humans and the atmosphere; therefore, quick detection is a vital need. The sol-gel self-combustion process was applied to synthesize the calcium-doped praseodymium orthoferrite (PrFeO3) nanomaterials. Synthesized nanoparticles were analyzed by powder X-ray diffraction (PXRD) for phase and crystallite size, energy dispersive X-ray (EDX) for elemental composition and field emission scanning electron microscopy (FESEM) for surface morphology, high-resolution transmission electron microscopy (HR-TEM) for structural and morphology, ultraviolet-visible (UV-vis) spectroscopy for absorption behavior and energy band gap, Brunauer-Emmett-Teller (BET) for surface analysis, and Fourier transform infrared spectroscopy (FTIR) for the vibrational study. The PXRD illustrates that the crystallite size reduces from 27.72 to 20.49 with the rising content of calcium. The FESEM and EDX interpret the morphology and elemental composition/mapping. The UV-vis spectroscopy reveals that the band gap is decreasing from 2.25 to 1.87 eV with the increasing concentration of calcium. The optimized nanomaterials were explored for LPG sensing. Recovery time, response time, sensor response, etc., were determined and discussed. This study divulges that the composition Pr0.8Ca0.2FeO3 has optimum sensor response, selectivity, and least response and recovery times of 7.5 and 7.1 s, respectively. The designed sensor shows good selectivity for LPG at ambient temperature. The current study points out that the developed sensor outperforms in terms of response and recovery times when compared with other LPG sensors based on perovskite materials. The gas sensing mechanism has been explained.

A novel nanoparticles spilled-over In2O3microcubes-enabled sustainable chemiresistor for environmental carbon dioxide monitoring

Achieving sustainable future energy goals includes enhancing renewable energy production, optimizing daily energy consumption using feedback loops and minimizing/monitoring contributions to atmospheric carbon dioxide (CO2). Developing economic next-generation CO2sensors enables local monitoring of industrial CO2emissions, aiding energy management and climate monitoring. This study elucidates the efficacy of CO2chemiresistor based on indium oxide (In2O3) micro cubes with spilled-over nanoparticles. The investigation primarily focuses on fabricating and optimising In2O3-based CO2chemiresistors utilizing a hydrothermal technique, creating porous micro cubes essential for enhanced CO2monitoring. As revealed by various characterization techniques, the minimum crystallite size was found to be 24.92 nm with optimum porosity and a high surface-to-volume ratio comprising spilled-over nanoparticle morphology. The fabricated chemiresistor demonstrated excellent CO2 sensing efficacy with a maximum response of around 4.1% at room temperature with selectivity, repeatability, and reversible sensing behavior. The sensing mechanism has been revealed, which is supported by theoretical density functional theory evaluations. Notably, the sensing results reveal the capability of In2O3-based sensors to detect CO2at low concentrations as low as ⩽10 ppm, which enables the chemiresistor for practical implementation in diverse sectors to achieve sustainability.

Advancements in lanthanide-based perovskite oxide semiconductors for gas sensing applications: a focus on doping effects and development

Lanthanide-based perovskite oxide semiconductors have garnered significant attention due to their exceptional electrical and sensing properties, making them promising candidates for gas sensing applications. This review paper focuses on developments and the impact of doping in lanthanide-based perovskite oxide semiconductors for gas sensing purposes. The review explores the factors influencing gas sensing performance, such as operating temperature, dopant selection, and target gas species. The role of dopants in enhancing gas sensing selectivity, sensitivity, response/recovery times, and stability is discussed in detail. Comparisons are drawn between doped perovskite oxide semiconductors, undoped counterparts, and other gas-sensing materials. Practical applications of lanthanide-based perovskite oxide semiconductor gas sensors are outlined, including environmental monitoring, industrial process control, and healthcare. The review also identifies current challenges and future perspectives in the field, such as the exploration of novel doping strategies and integration with emerging technologies like the Internet of Things (IoT). The findings emphasize the potential of these materials in advancing gas sensing technology and the importance of continued research in this field.

Synthesis of a porous SiO2-H3BO3-V2O5-P2O5 glassy composite: structural and surface morphological behaviour for CO2 gas sensing applications

The present work mainly focuses on the fabrication of a porous glass 40SiO2-35H3BO3-19V2O5-6P2O5 via a melt-quenching technique. The structural, morphological, and sensing behaviour of the glass sample was investigated successfully. The calculated density and molar volume of the fabricated glass are 2.4813 ± 0.124 g cm-3 and 35.7660 ± 1.708 cm3 mol-1. XRD, SEM and TEM analyses confirmed the amorphous nature of the glass. FTIR results revealed the O-H bond formations, which indicate that the presence of water molecules is probably due to the porous nature of the glass. Further, BET analysis confirmed the mesoporous nature of the glass sample with a mean pore diameter of 7 nm. The sensing response of the synthesized glass at 1000 ppm concentration of CO2 was found to be 3.05 with a response time 22.6 s and recovery time 25.8 s. Hence, this porous glass can be easily synthesized, is affordable, and was found to be useful for CO2 gas sensing applications.

Rare-Earth Doping in Nanostructured Inorganic Materials

Impurity doping is a promising method to impart new properties to various materials. Due to their unique optical, magnetic, and electrical properties, rare-earth ions have been extensively explored as active dopants in inorganic crystal lattices since the 18th century. Rare-earth doping can alter the crystallographic phase, morphology, and size, leading to tunable optical responses of doped nanomaterials. Moreover, rare-earth doping can control the ultimate electronic and catalytic performance of doped nanomaterials in a tunable and scalable manner, enabling significant improvements in energy harvesting and conversion. A better understanding of the critical role of rare-earth doping is a prerequisite for the development of an extensive repertoire of functional nanomaterials for practical applications. In this review, we highlight recent advances in rare-earth doping in inorganic nanomaterials and the associated applications in many fields. This review covers the key criteria for rare-earth doping, including basic electronic structures, lattice environments, and doping strategies, as well as fundamental design principles that enhance the electrical, optical, catalytic, and magnetic properties of the material. We also discuss future research directions and challenges in controlling rare-earth doping for new applications.

Nanostructured Cobalt Doped Barium Strontium Titanate Thin Films with Potential in CO2 Detection

In this work, (Ba_0.75Sr_0.25) (Ti_0.95Co_0.05) O₃ perovskite nanostructured material, denoted subsequently as Co-doped BaSrTiO₃, was synthesized in a one-step process in hydrothermal conditions. The obtained powder was heat-treated at 800 °C and 1000 °C, respectively, in order to study nanostructured powder behavior during thermal treatment. The Co-doped BaSrTiO₃ powder was pressed into pellets of 5.08 cm (2 inches) then used for thin film deposition onto commercial Al₂O₃ substrates by RF sputtering method. The microstructural, thermal, and gas sensing properties were investigated. The electrical and thermodynamic characterization allowed the evaluation of thermodynamic stability and the correlation of structural features with the sensing properties revealed under real operating conditions. The sensing behavior with respect to the temperature range between 23 and 400 °C, for a fixed CO₂ concentration of 3000 ppm, highlighted specific differences between Co-doped BaSrTiO₃ treated at 800 °C compared to that treated at 1000 °C. The influence of the relative humidity level on the CO₂ concentrations and the other potential interfering gases was also analyzed. Two possible mechanisms for CO₂ interaction were then proposed. The simple and low-cost technology, together with the high sensitivity when operating at room temperature corresponding to low power consumption, suggests that Co-doped BaSrTiO₃ has a good potential for use in developing portable CO₂ detectors.

Rare-earth-containing perovskite nanomaterials: design, synthesis, properties and applications

As star material, perovskites have been widely used in the fields of optics, photovoltaics, electronics, magnetics, catalysis, sensing, etc. However, some inherent shortcomings, such as low efficiency (power conversion efficiency, external quantum efficiency, etc.) and poor stability (against water, oxygen, ultraviolet light, etc.), limit their practical applications. Downsizing the materials into nanostructures and incorporating rare earth (RE) ions are effective means to improve their properties and broaden their applications. This review will systematically summarize the key points in the design, synthesis, property improvements and application expansion of RE-containing (including both RE-based and RE-doped) halide and oxide perovskite nanomaterials (PNMs). The critical factors of incorporating RE elements into different perovskite structures and the rational design of functional materials will be discussed in detail. The advantages and disadvantages of different synthesis methods for PNMs will be reviewed. This paper will also summarize some practical experiences in selecting suitable RE elements and designing multi-functional materials according to the mechanisms and principles of REs promoting the properties of perovskites. At the end of this review, we will provide an outlook on the opportunities and challenges of RE-containing PNMs in various fields.