Ocimum sanctum Leaf Extract-Assisted Green Synthesis of Pd-Doped CuO Nanoparticles for Highly Sensitive and Selective NO2 Gas Sensors

Anit K Ambedkar; Durvesh Gautam; Sagar Vikal; Manohar Singh; Ashwani Kumar; Amit Sanger; Kavita Sharma; Beer Pal Singh; Yogendra K Gautam

doi:10.1021/acsomega.3c03765

Ocimum sanctum Leaf Extract-Assisted Green Synthesis of Pd-Doped CuO Nanoparticles for Highly Sensitive and Selective NO₂ Gas Sensors

ACS Omega. 2023 Aug 2;8(32):29663-29673. doi: 10.1021/acsomega.3c03765. eCollection 2023 Aug 15.

Authors

Anit K Ambedkar¹, Durvesh Gautam¹, Sagar Vikal¹, Manohar Singh¹, Ashwani Kumar^{2

3}, Amit Sanger⁴, Kavita Sharma¹, Beer Pal Singh¹, Yogendra K Gautam¹

Affiliations

¹ Smart Materials and Sensor Laboratory, Department of Physics, Chaudhary Charan Singh University, Meerut, Uttar Pradesh 250004, India.
² Institute Instrumentation Centre, Indian Institute of Technology Roorkee, Roorkee, Uttrakhand 247667, India.
³ Department of Physics, Graphic Era (Deemed to be University), Dehradun, Uttarakhand 248002, India.
⁴ Department of Physics, Netaji Subhas University of Technology, Dwarka Sector-3, New Delhi 110078, India.

Abstract

In view of facile, cost-effective, and environmentally friendly synthetic methods, palladium-doped copper oxide (Pd-CuO) nanoparticles have been synthesized from Ocimum sanctum (commonly known as "Tulsi") phytoextract for gas-sensing applications. The structural, morphological, and compositional properties of Pd-doped CuO nanoparticles were studied using various techniques such as XRD, FESEM, XPS, and EDX. The characterization results confirmed the doping of Pd on CuO nanoparticles, and Pd-CuO nanostructures appear as nanoflakes in FESEM analysis. The gas-sensing response of Pd (1.12 wt %)-CuO nanoflake-based sensor was measured at 5-100 ppm concentration of different gases, NO₂, H₂S, NH₃, and H₂, at 125 °C. Gas-sensing tests reveal that the sensitivity of the sensor were 81.7 and 38.9% for 100 and 5 ppm concentrations of NO_2, respectively, which was significantly greater than that of pure CuO. The response and recovery times of the sensor were 72 and 98 s for 100 ppm of NO₂ gas, while they were 90 and 50 s for 5 ppm NO₂. The calculated limit of detection (LOD) value of the sensor is 0.8235. This appealing LOD is suitable for real-time gas detection. The gas sensor was found to exhibit excellent selectivity toward NO₂ gas and repeatability and stability in humid (80%) conditions. The Pd doping in CuO nanostructures plays a significant role in escalating the sensitivity and selectivity of CuO-based NO₂ gas sensor suitable to work at low operating temperatures.