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Due to poor selectivity, existing H2 sensors based on metal oxide semiconductor (MOS) nanostructures do not perform well at low concentrations. In this report, we have developed an improved sub-ppm H2 gas sensor based on Pt-decorated vertically aligned porous V x O y nanofilms (Pt/V x O y ) using the magnetron sputtering technique. The field emission scanning electron microscopy studies revealed that the as-grown V x O y nanofilms are vertically aligned with porous surface structures that are cross-linked. High-resolution transmission electron microscopy image results endorsed the growth of isolated island-like Pt nanoparticles (average size of ∼3.7 ± 0.2 nm). Our X-ray photoelectron spectrophotometry and XRD analyses confirmed the oxidation state and phase of the as-deposited V x O y nanofilm, which consisted of orthorhombic-V2O5 with orthorhombic-VO2 inclusions. The Pt/V x O y nanofilm sensors exhibited high sensing response (99.59%) combined with fast response time (7 s) and short recovery time (18 s) to 100 ppm H2 at 150 °C temperature compared to pristine V x O y (response ∼28.55% and response/recovery time ∼50 s/110 s). Also at room temperature, the Pt/V x O y nanofilm sensor exhibited a far better H2-sensing response of 9.65% compared to 1.13% response of pristine V x O y . In addition, we performed elaborate studies to test the selectivity, repeatability, and durability of the Pt/V x O y nanofilm sensors. With improved sensitivity and selectivity, our fabricated sensor allows the detection of trace-level H2 with an estimated limit of detection value of 97 ppb.

Ichthyofaunal diversity in Jia Bharali River of Assam, Northeast India, has been carried out from September 2018 to March 2021. The study emphasized the documentation of fish faunal diversity in relation to water parameters of previously undocumented ecological pockets of Himalayan foothill zones of north-bank landscapes of Assam. Study revealed altogether 69 fish species belonging to 6 orders and 20 families in Jia Bharali River. Cypriniformes was the most dominant (42 species) order followed by Siluriformes (14 species), Perciformes (8 species), Synbranchiformes (3 species), whereas, Beloniformes and Clupeiformes support one species each. The highest species diversity was found in Site-1 (H’ = 3.76) whereas, in terms of seasons, the highest species diversity was found in retreating monsoon (H’ = 3.80). Among the 69 species of fish, 56 species (81.16%) were IUCN categorized as Least Concern, 6 were Not Evaluated (8.7%), two species were Near Threatened (2.90%), three were Data Deficient (4.34%), and one species each was Endangered (1.45%) and Vulnerable (1.45%) respectively. Analysis of the relationships between water parameters and ichthyofaunal diversity showed a positive correlation between increasing dissolved oxygen and species richness. Water temperature and pH showed a positive correlation with species abundance in the study area.

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