Facile Synthesis and Characterization of NiS and Co-doped NiS Nanomaterials for Photocatalytic and Gas Sensing Applications

In this work, we report the synthesis of pristine and cobalt-doped nickel sulfide (Co-NiS) nanomaterials (NMs) via co-precipitation for dual applications in photocatalysis and gas sensing. FTIR, XRD, SEM-EDX, and HR-TEM analyses revealed vibrational modes, high crystallinity, significant reductions in particle size and morphology, and uniform incorporation of Co into NiS. UV-DRS analysis confirmed that Co-doping narrowed the band gap of NiS from 3.2 eV to 2.9 eV and enhanced visible-light absorption. The improved electronic composition facilitated higher photocatalytic degradation of Xylidine dye to 92% under simulated sunlight, exceeding the 87% achieved with pristine NiS, with superoxide radical anion (O₂⁻) as the chief reactive species. Co-doping also significantly altered the selectivity of gas sensing. NiS exhibited a gas-sensing sensitivity of 72% toward CO₂ at 120 °C; however, Co-NiS demonstrated excellent selectivity for liquefied petroleum gas (LPG), responding with 77% at 60 °C, which is highly energy-efficient. This performance enhancement results from a tailored morphology and Co-based electronic structure. Overall, our findings on Co-NiS as a bifunctional NMs are promising for advanced environmental remediation and low-energy gas sensors.

Graphical Abstract