Fe-doped NiO nanopowders for advanced photochemical applications: Synthesis, characterization, photo-assisted dye degradation and latent fingerprint visualization

The present study investigates the novel potential of Ni 1-x Fe x O (x = 0, 0.01, 0.03, 0.05, 0.07 & 0.09) nanoparticles fabricated through the solution combustion method using glutamine for the first time. The prepared nanoparticles were comprehensively investigated for their structural, optical, luminescence, dye-degradation (photocatalytic) and latent fingerprint visualization using various spectroscopic techniques. The XRD and XPS analysis confirmed the formation of a NiO in cubic structure and the existence of Ni MNPs when Fe is doped into the NiO matrix. Additionally, XPS investigation reveals the multivalence of Ni (Ni 0 , Ni 2+ , Ni 3+ ) and Fe (Fe 2+ and Fe 3+ ) in the Ni 1-x Fe x O nanocatalysts. The FE-SEM reveal morphological changes and increased agglomeration with higher Fe content, indicating structural modifications, while elemental mapping confirms the homogeneous distribution of Ni and O and effective Fe incorporation, enhancing catalytic properties while potentially compromising mechanical stability. Furthermore, the possible mechanism for the emergence of Ni MNPs is presented. The band gap of pure NiO is estimated to be 3.53 eV and reduces to 2.02 eV for 9 mol% of Fe, making it viable for degrading dyes under visible light . Further, the prepared nanocatalysts were tested against Brilliant Green (BG) dye under visible light and found their remarkable ability to degrade the dye (with a degradation efficiency of 99.4 % by Ni 0.91 Fe 0.09 O) in just 80 min, surpassing other reported nanocatalysts. According to PL studies, the nano-catalysts possess abundant defects induced by the Fe substitution and play a pivotal role in facilitating dye degradation through interactions with reactive oxygen species (ROS). Furthermore, the CIE chromaticity studies have confirmed that the emission occurs in the blue region. Based on the photocatalytic and PL analysis, the possible mechanism for dye degradation has been developed and demonstrated. The investigated results demonstrate the potential of Ni 1-x Fe x O nanoparticles as highly efficient photocatalysts for dye degradation. The nanoparticles revealed latent finger prints (LFPs) on three non-porous surfaces: a glass paperweight, a stapler, and a steel knife. Our results demonstrated the successful detection of three types of ridges – type I (eye, ridge end), type II (cross over, island, bifurcation), and type III (sweat pores) – on all surfaces. Our findings suggest that the synthesized Fe-doped NiO nanoparticles have great potential for advanced forensic applications and can also effectively degrade dye pollutants.