Cost effective green synthesis of NiO nanostructures as highly efficient photocatalysts for degradation of organic dyes

Abstract

Here, the cost effective green synthesis of nickel oxide (NiO) nanostructures has been reported. The organic capping and/or reducing agents were obtained by extraction from wastes of three different vegetables (cauliflower, potatoes and peas). The extracts of cauliflower and peas peels gave nanowhiskers while the extract of potato peels gave nanorods of NiO, as confirmed by scanning electron microscopy. X-ray diffraction analyses demonstrated the nanocrystalline cubic phase of NiO in all the samples. However, crystallite size varied with the extract of vegetable waste used. Fourier transform infrared analysis helps in identifying different vibrations, particularly Ni-O stretching vibrations, and diffuse reflectance spectra analyses led to the establishment of bandgap energies. The resulting NiO nanostructures were tested for their efficiencies as photocatalysts for Methylene blue degradation. All the three samples have shown significant photocatalytic activities. The exploration in this study clearly demonstrates the very high photocatalytic activities of the synthesised NiO nanostructures, which can be used as competent agents for treatment of wastewater to remove toxic dyes.

Steering Unit Cell Dipole and Internal Electric Field by Highly Dispersed Er atoms Embedded into NiO for Efficient CO2 Photoreduction

“…Similarly, CO was not detected while there is no light or without triethanolamine (TEOA) or replacing CO 2 with N 2 , indicating that any change of reaction condition will greatly affect the activity. To explore the source of CO, we have tracked carbon using 13 CO 2 isotope marker as the gas source (with and without catalyst in the system, respectively), as displayed in Figure 4e, the peak at m/z = 29 was attributed to 13 CO. As shown in Figure S17, Supporting Information, there is only negligible CO signal with the absence of catalyst in the system, which indeed proves that 13 CO is derived from the photoreduction of 13 CO 2 molecules rather than fragmentation of 13 CO 2 . In order to further explore the utilization efficiency of light, the activity tests over 2Er/NiO 1−x were also carried out under light irradiation of 420 nm and 550 nm (Figure S18, Supporting Information) respectively.…”

“…As a traditional antiferromagnetic material, NiO is widely used as cocatalyst in photocatalysis due to its high chemical stability. [ 12 ] In addition, the bandgap of traditional NiO (TNiO) is about 3.6–4.0 eV (related to surface defects and density), [ 13 ] and its conduction band (CB) position lies at −0.5 V (vs. NHE pH = 7), which is insufficient for reducing CO 2 to CO (−0.53 V) on the thermodynamics. Therefore, the reported activities of CO 2 photocatalytic reduction over T‐NiO are very low.…”

Green synthesis and characterisation of ZnMn 2 O 4 nanoparticles for photocatalytic degradation of Congo red dye and kinetic study

“…Measurement of optical absorption feature and electronic state of ZnMn 2 O 4 nanoparticles were surveyed by DRS. The bandgap energy was measured using a reflectance technique by exerting the Tauc theory (1) [37] (ahv) 2…”

“…1. Introduction: Approximately 15% of the total world manufacture of dyes is lost during the dyeing process and is released in the textile sewerages [1,2]. The release of those coloured wastewaters in the ecosystem is a demonstrative source of non-aesthetic pollution, eutrophication and perturbations in the aquatic life.…”

Green sol–gel synthesis of CoMnCrO 4 spinel nanoparticles and their photocatalytic application

“…In the present decade, nanoparticles have received serious attention in literature because of their properties and applications in gene and drug delivery, electronic devices, permanent magnet, microwave devices, biosensors and sensors, catalyst for diverse reactions, photocatalyst, and so on. Various methods were introduced for synthesis nanoparticles [1–5]. Green synthesis by plant extracts is a favourite method for researchers.…”