Photocatalytic improvement of Mn-adsorbed <i>g</i>-C₃N₄

Zhang, Weibin,Zhang, Zhijun,Kwon, Sangwoo,Zhang, Fuchun,Stephen, Boandoh,Kim, Ki Kang,Jung, Ranju,Kwon, Sera,Chung, Kwun-Bum,Yang, Woochul Elsevier BV 2017 Applied Catalysis B Vol.206 No.-

<P><B>Abstract</B></P> <P>This study employed experimental results and theoretical calculations to investigate Mn-adsorbed <I>g</I>-C<SUB>3</SUB>N<SUB>4</SUB> as a potential photocatalyst with high efficiency. Mn was chosen as the incorporating element, because among the 3<I>d</I> transition metals it exhibits the highest binding energy and most suitable band edge positions. The photocatalytic efficiency of Mn-adsorbed <I>g</I>-C<SUB>3</SUB>N<SUB>4</SUB> is 3 times higher that of pristine <I>g</I>-C<SUB>3</SUB>N<SUB>4</SUB>. Although small variations in the phase and surface morphology were observed, which were confirmed to not be the determining factors to improve efficiency. The factors that affect the high photocatalytic efficiency are therefore the electronic structure, optical absorption, and band edge variations after Mn-adsorption. The Mn atoms stably are bonded with N atoms, due to the strong absorption energy and ionic bond. Moreover, reduction of the <I>g</I>-C<SUB>3</SUB>N<SUB>4</SUB> band gap after Mn-adsorption results in a red shift of the absorption band edge. The half-filled Mn 3<I>d</I> state introduces impurity states into the forbidden band gap, which will increase the life time of charge carriers. In addition, the up-shifting of band edges of Mn-adsorbed <I>g</I>-C<SUB>3</SUB>N<SUB>4</SUB> leads to inhibition of the electron-hole recombination. As a consequence, the photocatalytic efficiency of Mn-adsorbed <I>g</I>-C<SUB>3</SUB>N<SUB>4</SUB> is enhanced due to the combination of the aforementioned effects.</P> <P><B>Highlights</B></P> <P> <UL> <LI> The photocatalytic efficiency of Mn-adsorbed <I>g</I>-C<SUB>3</SUB>N<SUB>4</SUB> is three times higher that of pristine <I>g</I>-C<SUB>3</SUB>N<SUB>4</SUB>. </LI> <LI> The Mn atoms adsorbed on <I>g</I>-C<SUB>3</SUB>N<SUB>4</SUB> stably form ionic bond with N atoms, as confirmed by DFT calculation and experiment. </LI> <LI> The photocatalytic efficiency enhancement of Mn-adsorbed <I>g</I>-C<SUB>3</SUB>N<SUB>4</SUB> is attributed to the decrease of band gap, the half-filled Mn 3d states in the forbidden gap, and the up-shifting of band edges. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

First-Principles Calculation the Electronic Structure and the Optical Properties of Mn-Decorated g-C3N4 for Photocatalytic Applications

Weibin Zhang,Hoon Young Cho,Zhijun Zhang,Woochul Yang,Ki Kang Kim,Fuchun Zhang 한국물리학회 2016 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.69 No.9

The electronic structure and the optical properties of Mn-decorated graphitic carbon nitride (g- C3N4) were investigated using the density functional method. The large absorption energy of the Mn atoms on the g-C3N4 surface was found to suppress the clustering of the Mn atoms, which led to a conservation of the photocatalytic activity. The electronic structures of the Mn-decorated g-C3N4 showed that impurity energy levels emerged in the forbidden band of g-C3N4 and that the band edge of g-C3N4 shifted upward to 0.40 eV. In addition, the calculated optical constants showed that the novel photon absorption in the range of visible light originated from electronic transitions from the N 2p states in the upper valence band to impurity Mn 3d states. Moreover, the photon absorption reached a maximum when all sites of triangular N holes were decorated with Mn atoms. Our results provide evidence that the Mn-decorated C3N4 system could be a highly-efficient photocatalyst for solar light due to the extension of the range of photon absorption to include almost all visible light.

Correlation between lateral size and gas sensing performance of MoSe₂ nanosheets

Zhang, Shaolin,Nguyen, Thuy Hang,Zhang, Weibin,Park, Youngsin,Yang, Woochul American Institute of Physics 2017 APPLIED PHYSICS LETTERS Vol.111 No.16

Synthesis of molybdenum diselenide nanosheets and its ethanol-sensing mechanism

Zhang, Shaolin,Zhang, Weibin,Nguyen, Thuy Hang,Jian, Jiawen,Yang, Woochul Elsevier 2019 Materials chemistry and physics Vol.222 No.-

<P><B>Abstract</B></P> <P>Molybdenum diselenide (MoSe<SUB>2</SUB>) nanosheets thin film gas sensor was firstly fabricated and its sensing potential to ppm-level ethanol vapor at low operating temperature was investigated. Ultrathin MoSe<SUB>2</SUB> nanosheets were prepared in large scale through a facile liquid-phase exfoliation method using low-boiling-temperature solvent. The exfoliated MoSe<SUB>2</SUB> nanosheets exhibited high purity and crystallinity with few atomic layer thickness. Systematical gas sensing tests demonstrated that MoSe<SUB>2</SUB> nanosheets based thin film could be utilized as ethanol gas sensor with linear response, quick recovery, and good repeatability at 90 °C. The sensing mechanism of MoSe<SUB>2</SUB> toward ethanol was investigated based on first principle calculation. The adsorption behavior of ethanol molecules on MoSe<SUB>2</SUB> surface was revealed in light of adsorption orientation, adsorption energy, charge transfer, projected electronic density of state, and molecular orbital. The calculation well matched with experimental results. It is found the quick and completed recovery of MoSe<SUB>2</SUB> nanosheets sensor was benefited by the appropriate physical interaction between ethanol and MoSe<SUB>2</SUB> surface. This finding offers a competitive option instead of conventional graphene sensor for ethanol gas detection at low temperature.</P>

Facile enhancement of photocatalytic efficiency of g-C₃N₄ by Li-intercalation

Zhang, Weibin,Zhang, Zhijun,Choi, Soo Ho,Yang, Woochul Elsevier 2019 CATALYSIS TODAY - Vol.321 No.-

<P><B>Abstract</B></P> <P>We report significant enhancement of photocatalytic properties of g-C<SUB>3</SUB>N<SUB>4</SUB> by a facile Lithium (Li)-intercalation method. The Li atoms are successfully and stably intercalated into the interlayer of g-C<SUB>3</SUB>N<SUB>4</SUB> by <I>n</I>-butyl lithium (<I>n</I>-BuLi). The photocatalytic activity of the Li-intercalated g-C<SUB>3</SUB>N<SUB>4</SUB> was observed to be significantly improved by 2.8 times in degradation of a dye (RhB), compared to that of pristine g-C<SUB>3</SUB>N<SUB>4</SUB>. The synergetic effects of the narrowed band gap, enhanced surface area, establishment of an interlayer pathway, and positive shift in the valence band position improve the photocatalytic activity of the Li-intercalated g-C<SUB>3</SUB>N<SUB>4</SUB>. Our discovery provides a promising route to manipulate the photocatalytic activity simply by increasing the Li concentration after the growth process of the g-C<SUB>3</SUB>N<SUB>4</SUB>, gaining a deeper understanding of the improvement in the photocatalytic efficiency.</P> <P><B>Highlights</B></P> <P> <UL> <LI> The Li atoms are stably intercalated into the interlayer of g-C<SUB>3</SUB>N<SUB>4</SUB>. </LI> <LI> The photocatalytic efficiency of Li-intercalated g-C<SUB>3</SUB>N<SUB>4</SUB> improves 2.8 times. </LI> <LI> The enhanced efficiency is due to synergetic effects induced by Li-intercalation. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Stability and Electronic Properties of Hydrogenated MoS₂ Monolayer: A First-Principles Study

Zhang, Weibin,Zhang, Zhijun,Yang, Woochul American Scientific Publishers 2015 Journal of Nanoscience and Nanotechnology Vol.15 No.10

<P>First-principles total energy studies are used to investigate the stability of hydrogenated MoS2 monolayer (MoS2-H-x) (x = 1-8), which is a compound with different numbers of H atoms adsorbed on the MoS2 surface. Energetically, the S-top side of the MoS2 is found to be the most favorable for H-adsorption. H2S and graphene are well-known to be stable, and MoS2-H-x is predicted to be even more stable because its binding energy is lower than that of H2S and its formation energy and adsorption energy are lower than those of graphene. The analysis of the electronic density distribution and the orbital hybrid also shows that MoS2-H-x forms stable structures. In addition, the influence of the number of the adsorbed H-atoms in the MoS2-H-x on the electronic structure of the compound is also investigated. The MoS2-H-x band structure exhibits a dispersion and the MoS2-H-x band gap gradually decreases from 1.72 eV to 0 eV as the number of adsorbed H atoms increases. The corresponding work function increases as a result of the strengthening of the dipole moment formed between the H atoms that are adsorbed and the hydrogenated MoS2.</P>

Pallidus Stimulation for Chorea-Acanthocytosis: A Systematic Review and Meta-Analysis of Individual Data

Weibin He,Chencheng Zhang 대한파킨슨병및이상운동질환학회 2022 Journal Of Movement Disorders Vol.15 No.3

A significant proportion of patients with chorea-acanthocytosis (ChAc) fail to respond to standard therapies. Recent evidence suggests that globus pallidus internus (GPi) deep brain stimulation (DBS) is a promising treatment option; however, reports are few and limited by sample sizes. We conducted a systematic literature review to evaluate the clinical outcome of GPi-DBS for ChAc. PubMed, Embase, and Cochrane Library databases were searched for relevant articles published before August 2021. The improvement of multiple motor and nonmotor symptoms was qualitatively presented. Improvements in the Unified Huntington’s Disease Rating Scale motor score (UHDRS-MS) were also analyzed during different follow-up periods.

Self-Supported Bi2MoO6 Nanosheet Arrays as Advanced Integrated Electrodes for Li-Ion Batteries with Super High Capacity and Long Cycle Life

Weibin Chen,Lina Zhang,Zhi-jing Ji,Ya-dan Zheng,Shuang Yuan,QIANG WANG 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2018 NANO Vol.13 No.6

Hierarchical Bi2MoO6 nanosheet arrays (BNAs) growing on three-dimensional (3D) Ni foam are synthesized by one-step template-free route. The obtained BNAs are used as binder-free integrated electrode for Li-ion batteries (LIBs) directly. The electrode exhibits a super high reversible discharge capacity of 2311.7 μAh·cm-2 (1741.4 mAhg-1), and an excellent cycle stability. The outstanding electrochemical properties are reasonable from the self-supported integrated electrode in which the electrolyte is easy to infiltrate active materials, electrons and ions are readily transported along the 3D conductive substrate and the stable electrode structure.

Targeting treatment of bladder cancer using PTK7 aptamer-gemcitabine conjugate

Xiang Wei,Peng Yongbo,Zeng Hongliang,Yu Chunping,Zhang Qun,Liu Biao,Liu Jiahao,Hu Xing,Wei Wensu,Deng Minhua,Wang Ning,Liu Xuewen,Xie Jianfei,Hou Weibin,Tang Jin,Long Zhi,Wang Long,Liu Jianye 한국생체재료학회 2023 생체재료학회지 Vol.27 No.00

Gemcitabine (GEM) is one of the first-line chemotherapies for bladder cancer (BC), but the GEMs cannot recognize cancer cells and have a low long-term response rate and high recurrence rate with side effects during the treatment of BC. Targeted transport of GEMs to mediate cytotoxicity to tumor and avoid the systemic side effects remains a challenge in the treatment of BC.Based on a firstly confirmed biomarker in BC-protein tyrosine kinase 7 (PTK7), which is overexpressed on the cell membrane surface in BC cells, a novel targeting system protein tyrosine kinase 7 aptamer-Gemcitabine conjugate (PTK7-GEMs) was designed and synthesized using a specific PTK7 aptamer and GEM through auto-synthesis method to deliver GEM against BC. In addition, the antitumor effects and safety evaluation of PTK7-GEMs was assessed with a series of in vitro and in vivo assays.PTK7-GEMs can specifically bind and enter to BC cells dependent on the expression levels of PTK7 and via the macropinocytosis pathway, which induced cytotoxicity after GEM cleavage from PTK7-GEMs respond to the intracellular phosphatase. Moreover, PTK7-GEMs showed stronger anti-tumor efficacy and excellent biosafety in three types of tumor xenograft mice models.These results demonstrated that PTK7-GEMs is a successful targeted aptamer-drug conjugates strategy (APDCs) to treat BC, which will provide new directions for the precision treatment of BC in the field of biomarker-oriented tumor targeted therapy.