Green synthesis and characterization of crystalline copper nanoparticles via sodium borohydride reduction towards enhanced gas sensing application

Copper nanoparticles were produced by a chemical reduction method from precursor copper sulfate using sodium borohydride as a reducing agent. Cu nanoparticles were created by the reduction of Cu2+ ions with NaBH4 in an alkaline solution. NaBH4 and CuSO4 have a molar ratio of 1.2 (6:5). CuSO4 has a concentration of 0.02 M, and 0.04 M NaBH4 was added dropwise to develop the precipitate. Further, characterizations were performed by X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Energy Dispersive X-ray Spectroscopy (EDS), Fourier Transform Infrared (FTIR) and Ultraviolet and Visible Spectroscopy (UV-Vis). The synthesis of the pure copper nanoparticles with a cubic crystalline structure was established. The average crystallite size of copper particle size is about 56.73 nm. The values of resistivity of the Cu conductive films were measured 4.1 × 103 Ω cm, 8 .8 × 10-2 Ω cm and 1.4 × 10-5 Ω cm at different atmospheric environments, including air, nitrogen gas, and hydrogen gas respectively.