Browsing by Author "Islam, Syed Z."

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Progress in Plasma Doping Semiconductor Photocatalysts for Efficient Pollutant Remediation and Hydrogen Generation
(Elsevier, 2023-09-01) Rahman, Tanzim Ur; Roy, Hridoy; Fariha, Athkia; Shoronika, Afrina Zaman; Al-Mamun, Md. Rashid; Islam, Syed Z.; Islam, Md. Shahinoor; Marwani, Hadi M.; Islam, Aminul; Alsukaibi, Abdulmohsen K.D.; Rahman, Mohammed M.; Awual, Md. Rabiul
In recent years, solar energy-driven photocatalysis materials have drawn significant attention to addressing the global energy and environmental crisis. However, many of the semiconductor photocatalysts are unable to absorb the visible light of the solar spectra due to their wide band gap. The incorporation of a foreign element such as a dopant in the lattice of these photocatalysts was shown to reduce their band gap and enhance visible light absorption. The doping of semiconductors can be performed using several techniques such as sol–gel, hydrothermal, solvothermal, and plasma-based doping. However, plasma-based doping has been considered a highly efficient approach due to the reduction of the band gap to a large extent, enhancement of visible light absorption, and remarkable photocatalytic activities under visible light illumination. The plasma-based doping approach offered many advantages such as high reactivity, process simplicity, scalability, energy efficiency, homogeneous doping, no chemical inventory, low pressure, and low-temperature operation, and flexibility of operation under gas and liquid phase media. Further advancement of plasma-based doping can be achieved through more theoretical studies allowing an in-depth understanding of the mechanisms and interactions of the species involved. This will facilitate the synthesis and application of doped photocatalysts in a cost-effective manner. This review surveyed recent advances in a wide range of semiconductor photocatalysts doped with various dopants using plasma treatment. Various plasma methods for doping semiconductor photocatalysts and their fundamental mechanisms were discussed. The performance characteristics of the plasma-doped photocatalysts were compared to other methods in terms of energy and environmental applications including degradation of environmental contaminants and solar fuel production such as hydrogen production from water splitting using visible light-driven solar energy. Finally, potential future research directions were recommended for the applications of the efficient photocatalysts developed by plasma treatment.
Toxic dye removal, remediation, and mechanism with doped SnO2-based nanocomposite photocatalysts: A critical review
(Daffodil International University, 2023-08) Roy, Hridoy; Rahman, Tanzim Ur; Khan, Md. Atquj Jaman Riad; Mamun, Md. Rashid Al-; Islam, Syed Z.; Khaleque, Md. Abdul; Hossain, Md. Ikram; Khan, Md. Zaved Hossain; Islam, Md. Shahinoor; Marwani, Hadi M.; Islam, Aminul; Hasan, Md. Munjur; Awual, Md. Rabiul
Heterogeneous photo catalysis is considered to be a sustainable solution for treating organic pollutants in wastewater. Tin oxide (SnO2) has received immense attention from researchers due to its excellent photocatalytic activity, low cost, thermal stability, and resistance to photo erosion. The structural properties of SnO2, different strategies for doping of SnO2, organic degradation mechanisms, and optimization of operational parameters for enhanced photocatalysis were critically analyzed. Photocatalytic activity of pristine SnO2 was enhanced by doping with metal oxide-based semiconductor materials, metals (transitional and earth), and non-metals. Doped SnO2 exhibits higher photocatalytic efficiency than pristine SnO2 due to the enhanced charge carrier separation, reduced electron-hole pair recombination, higher surface area, and lower band-gap energy. Green synthesized TiO2 doped SnO2 exhibited reduced band gap energy of 2.8 eV, and degraded 96 % MB within 75 min under visible light irradiation. The lowest bandgap energy for transitional metal-doped SnO2 was achieved by Mn-doping on SnO2 with a bandgap of ∼2.48 eV, whereas Cu-SnO2 and pure SnO2 have bandgap energies of 3.67 eV and ∼3.75 eV, respectively. Copper chromite spinel nanoparticles (CuCr2O4) doped SnO2 with a band gap energy of 1.39 eV degraded crystal violet (CV) dye completely at neutral pH. Gadolinium (Gd) doped SnO2 particles showed the highest surface area (58 m2/g) which was almost double the pristine SnO2 particles. The degradation of organic dyes by doped-SnO2 depended on initial pH, catalyst dosage, pollutants concentration, dose, light intensity, etc. For the degradation of cationic dye (MB), approximately 50 % more degradation was found at basic pH than at acidic pH utilizing pristine SnO2 nanoparticles. On the contrary, about 20 % more degradation was found for anionic dye (Congo Red) degradation at acidic pH compared to basic pH. Moreover, optimization of catalyst dosage can result in about 50 % more degradation of pollutants. The ZnS-doped SnO2 photocatalysts have shown an increased rate constant of photocatalytic reaction by 24.5 times when the concentration was reduced from 30 mg/L to 5 mg/L. This review also assessed the future research directions to develop sustainable organic pollutants-based wastewater using SnO2.