Efficient inactivation of <i>Pseudomonas aeruginosa</i> by Cu/Co-α-NiMoO₄ in visible light

Ray, Schindra Kumar,Dhakal, Dipesh,Sohng, Jae Kyung,Kim, Seung-Young,Lee, Soo Wohn Elsevier 2018 Chemical engineering journal Vol.347 No.-

<P><B>Abstract</B></P> <P>The Cu/Co-α-NiMoO<SUB>4</SUB> nanorods were fabricated by microwave hydrothermal process and characterized by various techniques. According to XRD/HRTEM/SAED/EDS analysis, the dopant ions were existed in the lattice of α-NiMoO<SUB>4</SUB>.The Cu/Co-α-NiMoO<SUB>4</SUB> samples have capacity to inactivate the multidrug resistant <I>Pseudomonas aeruginosa</I> in visible light within 180 min. Also, they revealed the excellent stability with reusability. The scavengers test indicates that H<SUB>2</SUB>O<SUB>2</SUB>/OH<SUP> </SUP>/O<SUB>2</SUB> <SUP> −</SUP>/h<SUP>+</SUP> play a crucial work for pathogen inactivation. Also, NBT assay suggested the enhancement of intracellular O<SUB>2</SUB> <SUP> −</SUP> production in Cu (33 folds) and Co doped (29 folds) α-NiMoO<SUB>4</SUB>. The FESEM analysis revealed dead bacteria cells by attack of active species on cell wall. Also, DNA fragmentation (gel electrophoresis) and protein degradation (Bradford assay) confirmed the inactivation of bacteria by active species. The evidence of superior biofilm penetration ability (69%) by doped photocatalyst was exhibited by well plate based crystal violet assay and TEM/EDS mapping. The band gap reduction, surface plasmon resonance effect, oxygen vacancy, electron-hole trapping by Cu<SUP>2+</SUP>/Co<SUP>2+</SUP>/Co<SUP>3+</SUP>, formation of intermediate energy band, and efficient separation of electron-hole pair were contributed for enhancement of the pathogen inactivation in visible light by doping of Cu and Co in α-NiMoO<SUB>4</SUB>. Also, Cu doped photocatalyst has slightly more pathogen inactivation efficacy than Co doped photocatalyst. The toxicity of photocatalyst was evaluated by using RAW 264.7 cells via MTT assay and the result revealed the toxicity. In conclusion, the Cu/Co-α-NiMoO<SUB>4</SUB> photocatalyst can be applied for efficient inactivation of multidrug resistant pathogen in biological waste water treatment.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Microwave hydrothermal synthesized Cu/Co-α-NiMoO<SUB>4</SUB> stable/reusable photocatalyst. </LI> <LI> Complete inactivation of <I>P</I>. <I>aeruginosa</I> within 180 min in visible light. </LI> <LI> Inactivation analysis by DNA fragmentation/protein degradation/FESEM of bacteria. </LI> <LI> Analysis of intracellular O<SUB>2</SUB> <SUP> −</SUP> production and toxicity effect in RAW 264.7 cells. </LI> <LI> TEM/EDS mapping/CV assay of biofilm for efficient inactivation. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

A review on monoclinic metal molybdate photocatalyst for environmental remediation

Schindra Kumar Ray,허진 한국공업화학회 2021 Journal of Industrial and Engineering Chemistry Vol.101 No.-

Utilization of solar energy by photocatalysts is a promising green technology for the degradation oforganic pollutants in wastewater. Among the various types of metal molybdate photocatalysts appliedfor environmental remediation, those with monoclinic structures (NiMoO4, CoMoO4, MnMoO4,ZnMoO4, Ce2(MoO4)3, Fe2(MoO4)3, and Bi2MoO6) constitute the largest group of them. These materialspossess many valuable properties such as tunable band structures, environmental friendliness, low cost,large surface areas, and tunable electrical conductivity. These promising materials have evidenced effectiveremoval capability for organic pollutants in wastewater. This review focuses on semiconductingmetal molybdates containing a monoclinic structure, with an emphasis on various modification strategiesemploying morphology control, doping, plasmonic material fabrication, or composite fabrication toenhance the photocatalytic activities for the degradation of organic pollutants. This review also discussesthe possible obstacles to environmental applications targeted at the removal of organic pollutants, as wellas the key challenges, future directions, and prospects.

Enhancement of Upconversion Luminescence in BaMoO₄: Er³⁺/Yb³⁺ Microcrystals by the Addition of KCl

Ray, Schindra Kumar,Adhikari, Rajesh,Joshi, Bhupendra,Gyawali, Gobinda,Kshetri, Yuwaraj K.,Regmi, Chhabilal,Tripathi, Khagendra,Lee, Soo Wohn American Scientific Publishers 2016 Journal of Nanoscience and Nanotechnology Vol.16 No.11

<P>BaMoO4, co-doped with Er3+, Yb3+ and K+, microcrystals were synthesized by the microwave hydrothermal process. The crystal structure and particle morphology were investigated by X-ray diffraction (XRD) and scanning electron microscopy (SEM), respectively. The XRD pattern revealed the tetragonal scheelite structure of BaMoO4. In addition, octahedron microcrystals around 0.5-2 mu m were found by SEM analysis. Compositional analysis and the chemical states of the samples were analyzed by X-ray photoelectron spectroscopy (XPS). UV-Vis diffuse reflectance spectra and luminescence properties were also analyzed by UV-Vis diffuse reflectance spectroscopy and photoluminescence spectroscopy. Two strong green emission peaks (526 nm and 554 nm) and one weak red emission peak (661 nm) were observed, which are related to the H-2(11/2) -> I-4(15/2), S-4(3/2) -> I-4(15/2) and F-4(9/2) -> I-4(15/2) transitions of the Er3+ ions, respectively, under 980 nm (CW) laser diode excitation. The green upconversion luminescence intensity was enhanced two times with the KCl addition.</P>

Rapid degradation of naproxen by AgBr-α-NiMoO₄ composite photocatalyst in visible light: Mechanism and pathways

Ray, Schindra Kumar,Dhakal, Dipesh,Lee, Soo Wohn Elsevier 2018 Chemical engineering journal Vol.347 No.-

<P><B>Abstract</B></P> <P>A novel strategy for fabrication of visible light driven AgBr-α-NiMoO<SUB>4</SUB> composite photocatalyst has been developed, including microwave hydrothermal and precipitation-deposition method. The fabrication of heterojunction photocatalyst was proved by XRD, FESEM mapping, HRTEM, SAED, EDS, and XPS techniques. The composite photocatalyst degraded naproxen drug around 84% within 20 min under visible light irradiation. The active species trapping experiment confirmed that OH<SUP> </SUP>, O<SUB>2</SUB> <SUP> −</SUP>, and h<SUP>+</SUP> play a crucial role for naproxen degradation. Due to efficient charge separation, well matched energy band of AgBr and α-NiMoO<SUB>4</SUB> as well as surface plasmon resonance of silver particles, the composite revealed the high photocatalytic performance with excellent stability up to fifth cycle. In addition, the composite is photochemical stable. Furthermore, the five degradation pathways were proposed on the basis of retention time and theoretical/observed molecular masses of 19 degraded organic fragments that was confirmed by high-performance liquid chromatography-photodiode array (HPLC-PDA) and high resolution-quadruple time of flight electrospray ionization mass spectroscopy (HR-QTOF ESI/MS) techniques. The different reactions (methylation, demethylation, decarboxylation, hydroxylation, oxidation, and coupling) were observed during NPX degradation by photocatalyst. TOC (total organic carbon) analysis revealed that naproxen drug was completely mineralized by composite photocatalyst within 100 min. So, this work represents the fabrication of visible light induced novel composite photocatalyst for rapid degradation of pharmaceutical pollutant with detailed mechanism and pathways.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Rapid degradation of naproxen by AgBr-α-NiMoO<SUB>4</SUB> in visible light within 20 min. </LI> <LI> Excellent photochemical stability of composite up to 5th cycle. </LI> <LI> Identification of nineteen degraded naproxen fragments by HR-QTOF ESI/MS. </LI> <LI> Proposed five different pathways for naproxen degradation. </LI> <LI> Complete mineralization of naproxen within 100 min. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Ag-BaMoO₄: Er³⁺/Yb³⁺ photocatalyst for antibacterial application

Ray, Schindra Kumar,Dhakal, Dipesh,Pandey, Ramesh Prasad,Lee, Soo Wohn Elsevier S.A. 2017 Materials Science and Engineering C Vol. No.

<P>Silver loaded and Er3+/Yb3+ doped BaMoO4 octahedron microcrystals were fabricated by microwave hydrothermal process. The synthesized samples were characterized by X-ray diffraction (XRD), Field emission scanning electron microscopy (FESEM), Energy dispersive X-ray spectroscopy (EDS), and Ultraviolet-visible diffuse reflection spectroscopy (UV-Vis DRS). The antibacterial application of samples were investigated by visible light irradiation and disk-diffusion method towards representative Gram-negative pathogen (Escherichia coli and Pseudomonas aeruginosa) and Gram-positive pathogen (methicillin resistant Staphylococcus aureus). The complete inactivation of Escherichia coli, Pseudomonas aeruginosa, and Staphylococcus aureus were observed by Ag-BaMoO4: Er3+/Yb3+ photocatalyst within 1 h, 4 h, and 5 h, respectively, under visible light irradiation. The high killing percentage and superior zone of inhibition revealed the excellent antibacterial performance. The FESEM images were used to visualize the morphology with the extent of damage in the phospholipid layer present in the cell membrane of bacteria. The synergistic effect of loaded silver particles and doped Er3+/Yb3+ ions in BaMoO4 contributed for efficient antibacterial performance in visible light as well as in the dark. The excellent antibacterial performance of Ag-BaMoO4: Er3+/Yb3+ photocatalyst makes the material suitable for smart weapon for multidrug-resistant microorganisms and disinfectants in biomedical application. (C) 2017 Elsevier B.V. All rights reserved.</P>

Plasmon and Upconversion Behavior in Ag—BaMoO₄: Er³⁺/Yb³⁺ Microcrystals

Ray, Schindra Kumar,Adhikari, Rajesh,Gyawali, Gobinda,Joshi, Bhupendra,Kshetri, Yuwaraj K.,Regmi, Chhabilal,Tripathi, Khagendra,Lee, Soo Wohn American Scientific Publishers 2016 Journal of Nanoscience and Nanotechnology Vol.16 No.11

<P>Ag-BaMoO4 co-doped with Er3+/Yb3+ microcrystals were synthesized by the microwave hydrothermal process. The crystal structures and particle morphology were observed by X-ray diffraction (XRD) and scanning electron microscopy (SEM), respectively. XRD patterns indicate the tetragonal scheelite structure of BaMoO4. Elemental composition was analyzed by X-ray photoelectron spectroscopy (XPS). UV-Vis diffuse reflectance spectra, Raman spectra and photoluminescence spectra were analyzed by UV-Vis diffuse reflectance spectroscopy, Raman spectroscopy and photoluminescence spectroscopy, respectively. Two strong green emission peaks (526 nm and 554 nm) and a weak red emission peak (661 nm) were identified, which were associated to the H-2(11/2) -> I-4(15/2), S-4(3/2) -> I-4(15/2) and F-4(9/2) -> I-4(15/2) transitions of the Er3+ ions, respectively. Moreover, two photonic processes were observed. The surface plasmon resonance (SPR) with upconversion luminescence behavior of the Ag-BaMoO4: Er3+/Yb3+ samples were clearly described.</P>

Characterization and multicolor upconversion emission properties of BaMoO₄: Yb³⁺, Ln³⁺ (Ln = Tm, Ho, Tm/Ho) microcrystals

Ray, Schindra Kumar,Kshetri, Yuwaraj K.,Yamaguchi, Tokutaro,Kim, Tae-Ho,Lee, Soo Wohn Elsevier 2019 Journal of solid state chemistry Vol.272 No.-

<P><B>Abstract</B></P> <P>Hydrothermal process was employed to synthesize the Yb<SUP>3+</SUP>/Tm<SUP>3+</SUP>, Yb<SUP>3+</SUP>/Ho<SUP>3+</SUP> and Yb<SUP>3+</SUP>/Tm<SUP>3+</SUP>/Ho<SUP>3+</SUP> doped BaMoO<SUB>4</SUB> octahedron microcrystals (0.50–5.0 µm). The synthesized phosphors have scheelite tetragonal structure. The elemental mapping suggests the uniform distribution of elements in the samples. The oxidation state of samples were investigated by X-ray photoelectron spectroscopy (XPS) which indicates the existence of Ba<SUP>2+</SUP>, Mo<SUP>6+</SUP>, O, Yb<SUP>3+</SUP>, Tm<SUP>3+</SUP> and Ho<SUP>3+</SUP> in samples. The presence of rare earth ions was also verified by observation of specific absorption peaks in diffuse reflectance spectra (DRS). The tunable multicolor upconversion (UC) emissions were successfully obtained under 980 nm NIR excitation by precisely adjusting the concentration of rare earth ions. The as prepared sample exhibits blue, green and red emission as a result of energy transfer from the Yb<SUP>3+</SUP> to Tm<SUP>3+</SUP> and Ho<SUP>3+</SUP> ions. The power dependent UC emission spectra show the two photonic processes. The energy transfer mechanism from Yb<SUP>3+</SUP> to Tm<SUP>3+</SUP> and Ho<SUP>3+</SUP> was explained <I>via</I> an energy level analysis.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Synthesis of BaMoO<SUB>4</SUB>: Yb<SUP>3+</SUP>, Ln<SUP>3+</SUP> (Ln = Tm, Ho, Tm/Ho) by hydrothermal process. </LI> <LI> Investigation of upconversion luminescence of phosphors under 980 nm excitation. </LI> <LI> Obtaining the multicolor emission by adjusting doped rare-earth ions concentration. </LI> <LI> Explanation of photonic process and energy transfer mechanism. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>Multicolor upconversion emission properties of BaMoO<SUB>4</SUB>: Yb<SUP>3+</SUP>, Ln<SUP>3+</SUP> (Ln = Tm, Ho, Tm/Ho) octahedrons</P> <P>[DISPLAY OMISSION]</P>

Inactivation of <i>Staphylococcus aureus</i> in visible light by morphology tuned α-NiMoO₄

Ray, Schindra Kumar,Dhakal, Dipesh,Regmi, Chhabilal,Yamaguchui, Tokutaro,Lee, Soo Wohn Elsevier 2018 Journal of photochemistry and photobiology. A, Che Vol.350 No.-

<P><B>Abstract</B></P> <P>α-NiMoO<SUB>4</SUB> has been successfully implemented in different morphologies <I>via</I> microwave hydrothermal technique in presence of surfactants (Polyethylene Glycol, Sodium Citrate, and Sodium Dodecyl Sulfate). The inactivation of multidrug-resistant pathogens, <I>Staphylococcus aureus</I> (<I>S. aureus</I>) has been investigated in the presence of visible light as well as in dark. <I>S. aureus</I> was inactivated in 6h under visible light irradiation. A slight inactivation of <I>S. aureus</I> was observed in dark. The generation of intracellular reactive oxygen species, ROS (O<SUB>2</SUB> <SUP>−</SUP>, OH, and H<SUB>2</SUB>O<SUB>2</SUB>) in visible light was observed by using 2, 7-dichloro-dihydro-fluorescein diacetate (DCFA-DA) and nitro blue tetrazolium (NBT), which suggests the bacterial inactivation by ROS. Nanowires morphology of α-NiMoO<SUB>4</SUB> exhibited effective bactericidal efficiency in visible light as compared to small bundle of needles, nanorod, large bundle of needles because of small size/diameter, toxicity, enhancement of ROS generation, and high BET surface area. The damages in the phospholipid layer present in the cell membrane of <I>S. aureus</I> were observed by FESEM analysis. Furthermore, the observation of DNA damages and protein degradation percentage give the evidence of ROS effect for deactivating the bacteria. So, this study offers new insight into the photocatalytic inactivation of multidrug-resistant microorganisms by morphology modulated visible light driven α-NiMoO<SUB>4</SUB> photocatalyst.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Fabrication of different morphologies α-NiMoO<SUB>4</SUB> by Microwave hydrothermal method. </LI> <LI> Tuning of morphology by surfactants (PEG, SC, and SDS). </LI> <LI> <I>S. aureus</I> inactivation in 6h under visible light. </LI> <LI> Analysis of damages in the cell membrane/DNA/protein degradation. </LI> <LI> Detection of ROS (O<SUB>2</SUB> <SUP>−</SUP>, OH, and H<SUB>2</SUB>O<SUB>2</SUB>) by DCFA-DA and NBT assay. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Rapid <i>Escherichia coli</i> inactivation in visible light by Fe/Zn-α-NiMoO₄ nanorod

Ray, Schindra Kumar,Pandey, Ramesh Prasad,Jeong, Sanghoon,Lee, Soo Wohn Elsevier 2018 Journal of photochemistry and photobiology Chemist Vol.367 No.-

<P><B>Abstract</B></P> <P>The microwave hydrothermal synthesized Fe and Zn doped α-NiMoO<SUB>4</SUB> nanorod was characterized by various techniques. The doping of metal ions into the lattice of α-NiMoO<SUB>4</SUB> was verified by HRTEM, SAED, and EDS analysis. The Fe and Zn doped α-NiMoO<SUB>4</SUB> photocatalyst completely inactivated the <I>Escherichia coli</I> in aqueous medium under visible light irradiation within 30 min and 45 min, respectively. The extending of absorption towards the visible light region or reduce in band gap, formation of new energy level in valance band and conduction band, trapping of generation of electron-hole pairs, oxygen vacancy, and efficient separation of electron-hole make the enhancement of photocatalytic disinfection by doped photocatalyst. Furthermore, the TEM images suggest the destruction of bacteria cell. The TEM elemental mapping of bacteria reveals that there is no release of toxic elements into the bacteria cell from the photocatalyst. So, these results demonstrated that the doped efficient photocatalyst can be applied for rapid inactivation of pathogens in infected waste water.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Microwave hydrothermal synthesized Fe and Zn doped α-NiMoO<SUB>4</SUB> nanorod. </LI> <LI> Rapid inactivation of <I>E. coli</I> in aq. medium within 30 min under VL irradiation. </LI> <LI> Visual destruction of bacteria on the basis of TEM images. </LI> <LI> No release of toxic ions from photocatalyst into bacteria cell. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

자성을 띄는 Z-scheme α-NimoO₄/ZnFe₂O₄/바이오차의 합성 및 광촉매 반응을 통한 케토프로펜 분해 연구

윤선호(Sunho Yoon),Schindra Kumar Ray,배성준(Sungjun Bae) 대한환경공학회 2022 대한환경공학회 학술발표논문집 Vol.2022 No.11