Enhancement in visible light photocatalytic performance using silver-decorated nickel titanate nanofiber composite

Assessment of photocatalytic activity of novel PrBiFeO3 perovskite composites in visible-light photocatalytic decomposition reaction

In this study, the visible-light photocatalytic reaction properties of perovskite catalysts was investigated with excellent visible-light sensitivity. Titanate-based and ferrite-based perovskites were introduced as light-responsive catalysts. A novel ferrite-based perovskite composite, PrBiFeO3, was synthesized, which demonstrated significantly enhanced light absorption under both visible light and UV illumination. The composite was prepared according to a combined sol-gel and solvothermal method. The newly synthesized PrBiFeO3 exhibited excellent absorption capabilities for both UV and visible light, with a band gap energy of about 2.0 eV. These perovskites showed photocatalytic activity in the decomposition of methylene blue and formaldehyde under visible light LED lamp illumination. Notably, the ferrite-based perovskites, including PrFeO3, displayed better photocatalytic activity under visible light compared to the titanate-based perovskites. The novel PrBiFeO3 composite also produced hydrogen and oxygen through water splitting under artificial sunlight and liquid plasma discharging. The amount of hydrogen produced by photocatalytic water splitting in PrBiFeO3 under liquid plasma irradiation was approximately 50 times higher than that produced under artificial sunlight irradiation.

CdTe QD-decorated GO nanosheet heterojunction for efficient photocurrent generation and photocatalytic activity

Cadmium telluride quantum dot (CdTe QD)-decorated graphene oxide (GO) nanosheets are promising heterojunctions for the environmental remediation of organic pollutants in water. However, assembling these two materials is a challenge. For this purpose, we have developed a one-step approach for the decoration of QDs onto the surface of GO nanosheets/intercalation of QDs into GO nanosheets through self-assembly, resulting in the formation of sandwiched hybrid heterojunctions. After synthesis, the samples were analysed for variations in their structural, morphological, compositional, optical and photoelectrochemical characteristics using various analytical tools. Interlinking QDs and GO nanosheets enhanced the photocurrent generation (∼5.8 μA cm-2), resulting in faster electron transfer by delaying the decay time (58.25 ms). A higher rate constant value (k = 0.135 min-1) was obtained for degrading 93% MB dye in 20 min. This work demonstrates a cost-effective strategy for constructing CdTe QDs/GO nanosheet hybrid heterojunctions for potential application in the field of photocatalysis.

Development of a visible-light-active-NiTiO3 coating for the efficient removal of the persistent herbicide 2,6-dichlorobenzamide (BAM) from drinking water

In the present research work, the photocatalytic evaluation of NiTiO3 nanoparticles immobilized on glass plates by the spin-coating procedure was carried out in the degradation of the recalcitrant herbicide 2,6-dichlorobenzamide (BAM). The concentrations of Ni employed to synthesize NiTiO3 nanoparticles were 1 wt% (1TESNi) and 2 wt% (2TESNi). The stability of coatings was evaluated by several washings and thermal treatments, which were verified by UV-vis analyses. The morphology of the coatings was studied by scanning electron microscopy (SEM-EDS). The coatings displayed thickness values of 1.35 and 2.56 μm for TiO2 and 1TESNi, respectively. The crystalline phases of the coatings were analyzed by X-ray diffraction (XRD), confirming the presence of NiTiO3 and other phases related to TiO2. The bandgap of 1TESNi, compared with the bare TiO2, was reduced from 2.96 to 2.40 eV as a consequence of Ni addition. The TiO2, 1TESNi and 2TESNi coatings were evaluated in the photodegradation of BAM using visible-light for 240 min. The highest effectiveness was displayed by the 1TESNi coating, obtaining degradation of 92.56% after 240 min. Also, the photocatalytic efficiency of the 1TESNi coating was only reduced 1.99% after 3 reuse cycles in the BAM degradation. The scavenger tests revealed that the main oxidizing species involved in the reaction were the •OH- and •O2- radicals. The 1TESNi coating showed the highest photocatalytic efficiency because of its absorption in the visible-light region, valuable surface area and electronic charge separation. Thus, these advantageous features guarantee that NiTiO3 coatings are an efficient method for degrading recalcitrant herbicides from drinking water using a practical way to recover and reuse photocatalysts.

Enhanced charge carrier transfer process in nickel titanate nanostructures for environmental remediation of industrial dye

The effective charge carrier transfer process in one-dimensional (1D) NiTiO₃ nanofibers and NiTiO₃ nanoparticles was demonstrated experimentally, showcasing an effective photocatalytic enhancement under visible light ambience. The rhombohedral crystal structure of NiTiO₃ nanostructures was confirmed using X-ray diffractometer (XRD). The morphology and optical characteristics of the synthesized nanostructures were characterized using scanning electron microscopy (SEM) and UV-visible spectroscopy (UV-Vis). Nitrogen adsorption-desorption analysis corresponding to NiTiO₃ nanofibers showcased porous structures with an average pore size of ~3.9 nm. The photoelectrochemical (PEC) measurement studies revealed an enhanced photocurrent for the NiTiO₃ nanostructures, confirming enhanced charge carriers transportation in fibers than in particles due to the delocalized electrons in the conduction band, thereby hindering the photoexcited charge carrier's recombination. The photodegradation efficiency of methylene blue (MB) dye under the visible light irradiation revealed an enhancement in the rate of degradation for NiTiO₃ nanofibers when compared to NiTiO₃ nanoparticles.