Enhanced ammonia gas sensing performance at room temperature of binder-free NiO, Cu and Co-doped NiO thin films synthesized via the SILAR method

We have comprehensively analyzed the influence of Cu and Co-doping on the structural, compositional, optical, and ammonia sensing characteristics of NiO thin films. The X-ray diffraction analysis revealed that pure NiO, Cu, and Co-doped NiO thin films possess a cubic structure. Remarkably, the Co-dopant caused a transformation in the crystallite size and surface structure of NiO. This alteration ultimately enhanced the sensing capabilities of Co-doped NiO thin films. The presence of Co decreased the amount of energy needed to activate Co-doped NiO, resulting in enhanced sensing capabilities of the doped samples for detecting 50 parts per million of ammonia with a response time of 20 s and recovery time of 16 s and having a percentage response of 76.25 %. The enhanced sensor responsiveness and selectivity of the Co-doped NiO sensor towards ammonia can be attributed to its increased surface area, smaller crystallite sizes, and superior surface properties. The remarkable results of Co-doped NiO thin films exhibited show a potential for use in the production of highly efficient ammonia gas-detecting devices.