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Iron vanadate (FeVO4) nanoparticles (NPs) were synthesized using the sol‐gel auto‐combustion technique, yielding a triclinic nanostructure as revealed by X‐ray diffraction (XRD). The average size, crystalline structure, and morphology of the nanoparticles were analyzed using field emission scanning electron microscopy (FESEM). Energy‐dispersive X‐ray spectroscopy (EDX) was used to investigate the elemental content and purity of the FeVO4 NPs. Fourier transform infrared spectroscopy (FTIR) confirmed the surface stretching frequency of the FeVO4 NPs. Using a doctor blade, the produced FeVO4 NPs were applied to the surface of a stainless steel (SS) substrate. The fabricated electrode was examined using GCD, EIS, and CV techniques. The absorption spectra exhibited strong absorbance in the visible range, with a band gap of 3.43 eV. Additionally, the FeVO4 electrode showed supercapacitor properties, with a maximum specific capacitance of 1151.05 F/g in a 1 M KOH electrolyte at a scan rate of 5 mV/s. These results indicate that the prepared FeVO4 electrode is promising for supercapacitor application due to their excellent electrochemical performance. [ABSTRACT FROM AUTHOR]

The Bismuth vanadate (BiVO4) nanoparticles were synthesized using the simple sol–gel auto-combustion method. The synthesized BiVO4 NPs showed monoclinic nanostructure in their X-ray diffraction (XRD) pattern. The field emission scanning electron microscopy (FESEM) was used to examine the surface morphology of the synthesized BiVO4 and using energy dispersive X-ray spectroscopy (EDX), the elemental content and purity of the fabricated NPs was verified. Fourier transform infrared spectroscopy (FT-IR) was used to identify the functional groups present on the surface of BiVO4 NPs. The absorption spectra of BiVO4 NPs showed large absorbance in visible region and band gap was found 2.32 eV. The photoluminescence (PL) spectroscopy showed a broadband peak of emission at 578 nm. These BiVO4 NPs also demonstrated supercapacitor characteristics. At a scan rate of 5 mV/s, the maximum specific capacitance was found to be 1160.05 F/g in a 1 M Na2SO4 electrolyte. The BiVO4 samples synthesized for use as supercapacitors have very low resistance and show the good electrochemical performance. [ABSTRACT FROM AUTHOR]

The prime objective of the current research was to analyze and utilize the coexistence of basic and acidic metal oxide semiconductors (MOS) for sensing pollutant gases. In the current work, 1 wt.%, 3 wt.%, 5 wt.%, 7 wt.%, and 9 wt.% NiO (basic MOS) was added to MoO3 (acidic MOS), and thick films were prepared using the screen printing technique. Structural characterization was performed by x-ray diffraction (XRD), scanning electron microscopy (SEM), and energy-dispersive x-ray analysis (EDAX). The crystallite size was about 50 nm, with intermediate voids. EDAX analysis confirmed the non-stoichiometric composition of the films. The films were oxygen-deficient as per EDAX data. An electrical analysis involving resistivity, temperature coefficient of resistance (TCR), and activation energy was also performed. NiO3 samples showed maximum resistivity of 103.13 × 104 Ω·m and minimum activation energy of 0.3953 eV. The electrical analysis predicted the distinct behavior of the NiO3 sample. A negative TCR value indicated the semiconductor-like behavior of the samples. The pollutant gas response of the samples was analyzed using a static gas sensing apparatus. NiO3 samples showed gas sensitivity of 87% towards the ethanol vapors, with good selectivity, as compared with the responses towards CO, liquid petroleum gas (LPG), NH3, and NO2 gases. The oxygen vacancy-based gas sensing mechanism was the probable reason for the improved ethanol vapor sensing. The response time of the sample was 28 s, while the recovery time was 38 s. [ABSTRACT FROM AUTHOR]

The aim of this study is to prepare thick films of MoO3 with various weight percentages of aluminum dopant and study its gas sensing characteristics. The thick films were prepared on alumina substrate using easily reproducible, cost-effective screen printing method. The films were characterized using XRD, FESEM, EDS and static gas sensing apparatus. The XRD analysis confirmed the presence of Molybdenum trioxide (JCPDS 05-0508) and aluminum (JCPDS 31-0026). The XRD conveyed that aluminum has occupied an interstitial position and got oxidized to alumina. FESEM showcased the characteristic lamellar structure of MoO3 with voids. The EDS data showed that films were having oxygen excess and the oxygen vacancies increased with aluminum doping percentage. Resistivity and activation energies decreased first and then increased with dopant (aluminum) percentage. The Al5 films showed a minimum resistivity (6 1. 0 5 × 1 0 4 Ω m) and activation energy (0.19 eV). The TCR had a negative value for all five films supporting n-type semiconductor behavior of the films. The Al5 films showed 84.3% sensitivity to 1000 ppm of NO2 gas at 200°C. Authors discussed adsorption-desorption based gas sensing mechanism in detail. Research work tested efficient NO2 gas sensor using aluminum-doped MoO3 thick films. [ABSTRACT FROM AUTHOR]