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Papers by Kaykobad Rezaul Karim

As rising atmospheric CO2 levels change Earth’s climate change, CO2 reduction has become an incre... more As rising atmospheric CO2 levels change Earth’s climate change, CO2 reduction has become an increasingly active area in energy research over the past several years. The present work is developing artificial photosynthesis technologies that use visible light to convert CO2 and water into methanol. In this study, TiO2 loaded copper oxide (CuO-TiO2) was synthesized, characterized and studied for photoelectrochemical (PEC) reduction of CO2 into methanol under visible light (λ > 470 nm) irradiation. In this perspective, the catalyst was synthesized via Sol-gel method. Catalyst characterization was done by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), UV-vis absorption spectra, and Mott-Schottky (MS). Linear sweep voltammetry (LSV) was employed to evaluate the photocatalytic activity of the prepared photocatalyst under visible light (λ >420 nm) irradiation for CO2 reduction reactions. XRD results indicated that the particle size of the as-prepared photocatalyst wa...

SSRN Electronic Journal, 2021

Bulletin of Chemical Reaction Engineering & Catalysis, 2018

In this work, p-type CuFe2O4 was synthesized by sol gel method. The prepared CuFe2O4 was used as ... more In this work, p-type CuFe2O4 was synthesized by sol gel method. The prepared CuFe2O4 was used as photocathode catalyst for photoelectrochemical (PEC) CO2 reduction. The XRD, UV-Visible Spectroscopy (UV-Vis), and Mott-Schottky (MS) experiments were done to characterize the catalyst. Linear sweep voltammetry (LSV) was employed to evaluate the visible light (λ>400 nm) effect of this catalyst for CO2 reduction. The band gap energy of the catalyst was calculated from the UV-Vis and was found 1.30 eV. Flat band potential of the prepared CuFe2O4 was also calculated and found 0.27 V versus Ag/AgCl. Under light irradiation in the CO2-saturated NaHCO3 solution, a remarkable current development associated with CO2 reduction was found during LSV for the prepared electrode from onset potential -0.89 V with a peak current emerged at -1.01 V (vs Ag/AgCl) representing the occurrence of CO2 reduction reaction. In addition, the mechanism of PEC was proposed for the photocathode where the necessit...

Bulletin of Chemical Reaction Engineering & Catalysis, 2019

This paper reports the photocatalytic decomposition of methylene blue (MB) over titania doped cop... more This paper reports the photocatalytic decomposition of methylene blue (MB) over titania doped copper ferrite, CuFe2O4/TiO2 with 50 wt% loading, synthesized via sol-gel method. The synthesized photocatalyst was characterized by X-ray diffraction, UV-vis diffuse reflectance, and photoluminescence, Mott-Schottky (MS) analysis and linear sweep voltammetry (LSV). The catalyst loadings were varied from 0.25 – 1.0 g/L and the optimum catalyst loading found to be 0.5 g/L. At the optimum loading, the conversion achieved was 83.7%. The other loadings produced slightly lower conversions at 82.7%, 80.6% and 80.0%, corresponding to 0.25, 1 and 0.75 g/L after 3 hours of irradiation. The study on the effect of initial concentration indicated that 20 ppm as the optimum concentration, tested with 0.5 g/L catalyst loading. The spent catalyst was used for the recyclability test and demonstrated a high longevity with a degradation efficiency less than 6 % for each time interval. The novelty of this stu...

Environmental Research, 2020

In this work, the photocatalytic property of p-type CuO was tailored by creating a heterojunction... more In this work, the photocatalytic property of p-type CuO was tailored by creating a heterojunction with n-type CdS. The CuO/CdS nanocomposite photocatalyst was synthesized by the ultrasound-assisted-wet-impregnation method and the physicochemical and optical properties of the catalysts were evaluated by using N2 physisorption, X-Ray Diffraction (XRD),X-Ray Photoelectron Spectroscopy (XPS), Raman spectroscopy, Transmission electron microscopy (TEM), Energy dispersive X-Ray (EDX) mapping, Field Emission Scanning Electron Microscope (FE-SEM), UV-Vis and photoluminescence spectroscopy experiments. Detailed characterization revealed the formation of a nanocomposite with a remarkable improvement in the charge carrier (electron/hole) separation. The photocatalytic degradation efficiencies of CuO and CuO/CdS were investigated for different dyes, for instance, rhodamine B (RhB), methylene blue (MLB), methyl blue (MB) and methyl orange (MO) under visible light irradiation. The obtained dye degradation efficiencies were ~93%, ~75%, ~83% and ~80%, respectively. The quantum yield for RhB degradation under visible light was 6.5 × 10-5. Reusability tests revealed that the CuO/CdS photocatalyst was recyclable up to four times. The possible mechanisms for the photocatalytic dye degradation over CuO/CdS nanocomposite were elucidated by utilizing various scavengers. Through these studies, it can be confirmed that the conduction band edges of CuO and CdS play a significant role in producing O2-. The produced O2- degraded the dye molecules in the bulk solution whereas the valence band position of CuO acted as the water oxidation site. In conclusion, the incorporation of CuO with CdS was demonstrated to be a viable strategy for the efficient photocatalytic degradation of dyes in aqueous solutions.

Journal of Nanoscience and Nanotechnology, 2019

Corn-cobs are an agro-industrial waste and composed of cellulose mostly. In this study cellulose ... more Corn-cobs are an agro-industrial waste and composed of cellulose mostly. In this study cellulose was isolated from the waste corn-cobs and modified to polymeric hydroxamic acid palladium complex 1 and characterized by using a variety of spectroscopic methods such as field emission scanning electron microscopy (FE-SEM), energy-dispersive X-ray spectroscopy (EDX), transmission electron microscopy (TEM), X-ray powder diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and inductively coupled plasma atomic emission spectroscopy (ICP-AES). The complex 1 exhibited high catalytic activity towards Suzuki and Heck coupling reactions of activated and deactivated aryl halides to give the respective coupling products with high yield. Moreover, the complex 1 was recovered and recycled five times with no considerable loss of catalytic overall performance.

Bioresource Technology Reports, 2020

Abstract In this present study, the extracted oil from the mesocarp fibers was characterized by t... more Abstract In this present study, the extracted oil from the mesocarp fibers was characterized by the determination of iodine, free fatty acid, ester and acid value found in a reasonable range which contained a remarkable amount of fatty acids. The Reichert-Meissl values were found zero indicating the lower rancidity properties of these oils. B. flabellifer crude oil contains lauric, tetradecanoic, palmitic, palmitoleic, octadecanoic, cis-9-oleic, linoleic, linolenic, docosanoic acid whereas the N. fruticans contains the same fatty acids with an extra arachidic, except palmitic acid. The phytochemical screening revealed the presence of tannin, phenolic, and flavonoid content for both samples. Antioxidant results showed that the IC50 for B. flabellifer was lower than N. fruticans suggesting that the B. flabellifer was more effective than N. fruticans as a preservative which might be due to the presence of phenolic and flavonoid contents that could be used as potential medicinal and preservative agents.

As rising atmospheric CO2 levels change Earth’s climate change, CO2 reduction has become an incre... more As rising atmospheric CO2 levels change Earth’s climate change, CO2 reduction has become an increasingly active area in energy research over the past several years. The present work is developing artificial photosynthesis technologies that use visible light to convert CO2 and water into methanol. In this study, TiO2 loaded copper oxide (CuO-TiO2) was synthesized, characterized and studied for photoelectrochemical (PEC) reduction of CO2 into methanol under visible light (λ > 470 nm) irradiation. In this perspective, the catalyst was synthesized via Sol-gel method. Catalyst characterization was done by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), UV-vis absorption spectra, and Mott-Schottky (MS). Linear sweep voltammetry (LSV) was employed to evaluate the photocatalytic activity of the prepared photocatalyst under visible light (λ >420 nm) irradiation for CO2 reduction reactions. XRD results indicated that the particle size of the as-prepared photocatalyst wa...

SSRN Electronic Journal, 2021

Bulletin of Chemical Reaction Engineering & Catalysis, 2018

In this work, p-type CuFe2O4 was synthesized by sol gel method. The prepared CuFe2O4 was used as ... more In this work, p-type CuFe2O4 was synthesized by sol gel method. The prepared CuFe2O4 was used as photocathode catalyst for photoelectrochemical (PEC) CO2 reduction. The XRD, UV-Visible Spectroscopy (UV-Vis), and Mott-Schottky (MS) experiments were done to characterize the catalyst. Linear sweep voltammetry (LSV) was employed to evaluate the visible light (λ>400 nm) effect of this catalyst for CO2 reduction. The band gap energy of the catalyst was calculated from the UV-Vis and was found 1.30 eV. Flat band potential of the prepared CuFe2O4 was also calculated and found 0.27 V versus Ag/AgCl. Under light irradiation in the CO2-saturated NaHCO3 solution, a remarkable current development associated with CO2 reduction was found during LSV for the prepared electrode from onset potential -0.89 V with a peak current emerged at -1.01 V (vs Ag/AgCl) representing the occurrence of CO2 reduction reaction. In addition, the mechanism of PEC was proposed for the photocathode where the necessit...

Bulletin of Chemical Reaction Engineering & Catalysis, 2019

This paper reports the photocatalytic decomposition of methylene blue (MB) over titania doped cop... more This paper reports the photocatalytic decomposition of methylene blue (MB) over titania doped copper ferrite, CuFe2O4/TiO2 with 50 wt% loading, synthesized via sol-gel method. The synthesized photocatalyst was characterized by X-ray diffraction, UV-vis diffuse reflectance, and photoluminescence, Mott-Schottky (MS) analysis and linear sweep voltammetry (LSV). The catalyst loadings were varied from 0.25 – 1.0 g/L and the optimum catalyst loading found to be 0.5 g/L. At the optimum loading, the conversion achieved was 83.7%. The other loadings produced slightly lower conversions at 82.7%, 80.6% and 80.0%, corresponding to 0.25, 1 and 0.75 g/L after 3 hours of irradiation. The study on the effect of initial concentration indicated that 20 ppm as the optimum concentration, tested with 0.5 g/L catalyst loading. The spent catalyst was used for the recyclability test and demonstrated a high longevity with a degradation efficiency less than 6 % for each time interval. The novelty of this stu...

Environmental Research, 2020

In this work, the photocatalytic property of p-type CuO was tailored by creating a heterojunction... more In this work, the photocatalytic property of p-type CuO was tailored by creating a heterojunction with n-type CdS. The CuO/CdS nanocomposite photocatalyst was synthesized by the ultrasound-assisted-wet-impregnation method and the physicochemical and optical properties of the catalysts were evaluated by using N2 physisorption, X-Ray Diffraction (XRD),X-Ray Photoelectron Spectroscopy (XPS), Raman spectroscopy, Transmission electron microscopy (TEM), Energy dispersive X-Ray (EDX) mapping, Field Emission Scanning Electron Microscope (FE-SEM), UV-Vis and photoluminescence spectroscopy experiments. Detailed characterization revealed the formation of a nanocomposite with a remarkable improvement in the charge carrier (electron/hole) separation. The photocatalytic degradation efficiencies of CuO and CuO/CdS were investigated for different dyes, for instance, rhodamine B (RhB), methylene blue (MLB), methyl blue (MB) and methyl orange (MO) under visible light irradiation. The obtained dye degradation efficiencies were ~93%, ~75%, ~83% and ~80%, respectively. The quantum yield for RhB degradation under visible light was 6.5 × 10-5. Reusability tests revealed that the CuO/CdS photocatalyst was recyclable up to four times. The possible mechanisms for the photocatalytic dye degradation over CuO/CdS nanocomposite were elucidated by utilizing various scavengers. Through these studies, it can be confirmed that the conduction band edges of CuO and CdS play a significant role in producing O2-. The produced O2- degraded the dye molecules in the bulk solution whereas the valence band position of CuO acted as the water oxidation site. In conclusion, the incorporation of CuO with CdS was demonstrated to be a viable strategy for the efficient photocatalytic degradation of dyes in aqueous solutions.

Journal of Nanoscience and Nanotechnology, 2019

Corn-cobs are an agro-industrial waste and composed of cellulose mostly. In this study cellulose ... more Corn-cobs are an agro-industrial waste and composed of cellulose mostly. In this study cellulose was isolated from the waste corn-cobs and modified to polymeric hydroxamic acid palladium complex 1 and characterized by using a variety of spectroscopic methods such as field emission scanning electron microscopy (FE-SEM), energy-dispersive X-ray spectroscopy (EDX), transmission electron microscopy (TEM), X-ray powder diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and inductively coupled plasma atomic emission spectroscopy (ICP-AES). The complex 1 exhibited high catalytic activity towards Suzuki and Heck coupling reactions of activated and deactivated aryl halides to give the respective coupling products with high yield. Moreover, the complex 1 was recovered and recycled five times with no considerable loss of catalytic overall performance.

Bioresource Technology Reports, 2020

Abstract In this present study, the extracted oil from the mesocarp fibers was characterized by t... more Abstract In this present study, the extracted oil from the mesocarp fibers was characterized by the determination of iodine, free fatty acid, ester and acid value found in a reasonable range which contained a remarkable amount of fatty acids. The Reichert-Meissl values were found zero indicating the lower rancidity properties of these oils. B. flabellifer crude oil contains lauric, tetradecanoic, palmitic, palmitoleic, octadecanoic, cis-9-oleic, linoleic, linolenic, docosanoic acid whereas the N. fruticans contains the same fatty acids with an extra arachidic, except palmitic acid. The phytochemical screening revealed the presence of tannin, phenolic, and flavonoid content for both samples. Antioxidant results showed that the IC50 for B. flabellifer was lower than N. fruticans suggesting that the B. flabellifer was more effective than N. fruticans as a preservative which might be due to the presence of phenolic and flavonoid contents that could be used as potential medicinal and preservative agents.