Tin oxide (SnO2) possesses many qualities that are useful for photonics applications, including a wide band gap (3.6 eV). The study published in Materials Today: Proceedings studied the properties of pristine SnO2 and nickel-doped SnO2 fabricated using the sol-gel method.
Study: Synthesis and photocatalytic activity of Ni doped SnO2 nanoparticles for removal of toxic industrial dyes. Image Credit: Mrs_ya/Shutterstock.com
Importance of Metal Oxide Nanoparticles
Metallic oxide nanoparticles (MONPs) are one of the most highly utilized materials within nanotechnology. As a result, techniques are developed to design MONPs-based systems with limited expense and better detection precision.
These nanostructures have properties that make them irresistible in the configuration of optoelectronics devices. Metal oxide semiconductors (MOSs), which have a significantly wider optical band gap (greater than 3.0 eV), have diverse usage in sensing applications. These materials are also thought to have great potential for degradation of organic pollutants when exposed to ultraviolet light.
What are the Harmful Effects of Dyes?
Pollutants and dyes released from industries such as pharmaceutical, cosmeceutical, and fabric industries can be hazardous. These contaminants are the leading causes of air and water pollution. Dye toxins must be thoroughly removed to prevent negative consequences on the environment and human health.
The Challenges in Dye Degradation
Dyes are resistant to degradation under normal circumstances due to their consistent and complex morphology. As a result, it has become a challenging issue for scientists to develop solutions for the successful, cost-effective removal of dyes in a short period.
Nanoparticles have a large surface area, substantial permeability, and hyperactivity, and the cumulative effect of these properties can aid in the cleanup of dye groundwater pollution.
Advantages of Tin Oxide
Tin oxide (SnO2) has a tetragonal morphological structure, a large bandgap (3.6 eV) and exhibits high thermal conductivity, sensitivity, selectivity, and cytocompatibility. When SnO2 is doped with metal dopants such as iron or copper, its compositional, optoelectronic, ferromagnetic, and electrochemical characteristics are altered.
Why Dope with Nickel?
Using metals as a dopant has contributed to increased responsivity and boosting interfacial preservation. Nickel (Ni) is a highly used doping substance that has resulted in SnO2 achieving excellent photocatalytic activity and selectivity. Ni doping has helped achieve improved photoinduced electrocatalytic activity by increasing SnO2’s light absorption capacity.
Introduction to the Sol-Gel Method
The sol-gel process is a wet chemical preparation method for producing diverse nanomaterials, particularly metal oxide nanomaterials. For nanoparticle synthesis, the sol-gel technique offers enhanced synthetic uniformity, high crystallinity, restricted elemental composition, reduced operating temperature, and other benefits that other wet-chemical methods do not provide. The sol-gel method was utilized in the study to create the nanoparticles.
The researchers utilized industrial-grade Congo red for the optical degradation study. All of the diffraction peaks showed an amorphous tetragonal crystalline morphology of SnO2. The pure and doped specimens were both crystalline in nature, without any other contaminant peaks associated with NiO or Sn2O4. The nanotubes were discovered to overlap, revealing a few densely packed frameworks.
The presence of Ni alloying elements in the SnO2 crystalline structure was confirmed using energy dispersive x-ray (EDX) measurements. Pure SnO2 was absorbed at 332 nm and had an optical absorption of 3.73 eV. This value was greater than the published granular band gap of uncontaminated tin oxide of 3.59 eV.
For photoluminescence (PL) spectrum analysis, to capture the emission spectra, the specimens were energized at 325 nm. The trends of the pure and doped specimens were almost equivalent, except for an increase in the magnitude of the contaminated specimen.
Was it Helpful in Removal of Toxic Dyes?
Congo red (CR) solution was exposed to an ultraviolet beam for 30 minutes under the inﬂuences of photocatalytic substances. In the optical absorption of CR, two significant concentration peaks were detected around 342 nm and 498 nm, whose amplitude significantly lowered and the contour became narrower.
Ni dopant was discovered to participate more actively in hindering the hybridization of photoinduced electron and hole combinations, resulting in the highest dye mineral deposits. It also improved tin oxide's light absorption capacity, leading to improved photocatalysts and higher degradation eﬃciency.
In short, Ni-SnO2 has higher photocatalytic degradation effectiveness (83%) than pristine SnO2 (74%) thanks to the advances in the high recombination inhibitory activity. This research paves the way for the industrialization of metal-doped nanoparticle oxides for the removal of contaminants, especially from water resources.
Mishra, P. K., Biswal, S. K. & Sahu, D., 2022. Synthesis and photocatalytic activity of Ni doped SnO2 nanoparticles for removal of toxic industrial dyes. Materials Today: Proceedings. Available at: https://www.sciencedirect.com/science/article/pii/S2214785322040536?via%3Dihub