NbC/C heterojunction for efficient photodegradation of methylene blue under visible irradiation

[Display omitted] •In-situ NbC/C heterojunction has been synthesized at low temperature (800 °C).•Multi-layered g-C sheets exhibited the defects associated to grain boundaries.•Presence of NbCxOy/NbOx centers and defected graphite induce optical absorption ability.•100% discoloration of MB dye has b...

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Bibliographic Details
Published in:Solar energy 2019-05, Vol.183, p.398-409
Main Authors: Gupta, Aayush, Pandey, O.P.
Format: Article
Language:English
Subjects:
Carbon sources
Carrot grass
Chemical reduction
Degradation mechanism
Dyes
Electrochemistry
Heterojunctions
Heterostructures
Hydrogen evolution reactions
Irradiation
Low temperature
Mass spectrometry
Mass spectroscopy
Metal powders
Methylene blue
Nanocomposite
Nanoparticles
NbC
Niobium
Niobium carbide
Niobium oxides
Organic chemistry
Oxygen reduction reactions
Photocatalysis
Photodegradation
Purification
Solar energy
Titanium dioxide
Transmission electron microscopy
Waste utilization
Wastewater
Wastewater purification
Water purification
Water splitting
Water treatment
X ray photoelectron spectroscopy
X-ray diffraction
Zinc oxide
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Summary:[Display omitted] •In-situ NbC/C heterojunction has been synthesized at low temperature (800 °C).•Multi-layered g-C sheets exhibited the defects associated to grain boundaries.•Presence of NbCxOy/NbOx centers and defected graphite induce optical absorption ability.•100% discoloration of MB dye has been observed under visible irradiation of 8 h. Photocatalysis has emerged as a vital tool for purification of waste water and also to obtain alternate fuels (H2) through water splitting. TiO2, ZnO and other non-carbide systems (ZnS, metallic nanoparticles (NPs), etc.) have been studied thoroughly to enhance their photocatalytic performances through doping and the formation of heterojunctions. But, niobium carbide (NbC) is gaining interest of researchers due to its ability to catalyze electrochemical reactions (hydrogen evolution reaction and oxygen reduction reaction) along with excellent thermal and chemical stability. In the present work, NbC has been synthesized using conventional oxide precursor (Nb2O5), Mg metal powder and parthenium hysterophorous (PH; carrot grass, an agricultural hazardous weed) as carbon source at relatively low temperature (800 °C) as compared to conventional synthesis temperature (1200 °C). For the phase confirmation and morphological studies, X-ray diffraction and transmission electron microscopy have been done. It has been observed that the presence of NbCxOy/NbOz inside NbC nanoparticles induced the optical active sites resulting photocatalytic degradation of methylene blue (MB) dye under visible irradiation. With the help of various techniques (UV–visible, PL, XPS, RAMAN spectroscopies and scavenger tests), degradation mechanism has been established for the observed photocatalytic performance of synthesized NbCxOy/NbOz/NbCx/g-C heterostructure under optimized conditions. Further, for the confirmation of photodegradation of MB dye, mass spectrometry and TOC have also been carried out.
ISSN:0038-092X
1471-1257
DOI:10.1016/j.solener.2019.03.040