Department of Microelectronics
Faculty of Electrical Engineering, Mathematics, and Computer Science

Xiangdong Feng

Publications

  1. Sheet-on-sheet architectural assembly of MOF/graphene for high-stability NO sensing at room temperature
    Yanwei Chang; Jingxing Zhang; Ruofei Lu; Weiran Li; Yuchen Feng; Yixun Gao; Haihong Yang; Fengnan Wang; Hao Li; Yi-Kuen Lee; Patrick J. French; Ahmad M. Umar Siddiqui; Yao Wang; Guofu Zhou;
    Journal of Materials Chemistry C,
    Volume 12, pp. 7520-7531, 2024. DOI: DOI: 10.1039/d4tc00091a
    Abstract: ... Fractional exhaled nitric oxide (FeNO) can be used to describe inflammatory processes in the respiratory tract. Directly detecting ppb-level nitric oxide (NO) with chemiresistive sensors at room temperature faces the challenges of simultaneously obtaining high sensitivity and high stability for sensors. We aimed to improve the stability and sensitivity of NO sensors. We assembled sheet-like porphyrin-based MOF DLS-2D-Co-TCPP(Fe) with 5-aminonaphthalene-1-sulfonic acid–rGO (ANS–rGO) nanosheets through coordination interactions. In this way, we offered a room-temperature NO-sensing hybrid, DLS-2D-Co-TCPP(Fe)/ANS–rGO, with a sheet-on-sheet (SOS) architectural heterojunction. The DLS-2D-Co-TCPP(Fe)/ANS–rGO-based sensor demonstrated superior NO-sensing performance, including high sensitivity (Ra/Rg = 1.33, 250 ppb), reliable repeatability, high selectivity, and fast response/recovery (150 s/185 s, 1 ppm) at a sensing concentration from 100 ppb to 10 ppm at room temperature. The obtained sensor showed high stability, retaining >85% of its initial response after 60 days. Designing NO-responsive Fe–N4 active units containing MOF nanosheets, along with constructing a heterojunction with an SOS architecture to facilitate carrier migration, collaboratively dominated the superior performance of synthesized NO sensors. This work provides a strategy for designing SOS architectural heterojunctions to obtain high-performance MOF-based gas-sensing materials.

  2. Patching sulfur vacancies: A versatile approach for achieving ultrasensitive gas sensors based on transition metal dichalcogenides
    Xiangcheng Liu; Yue Niu; Duo Jin; Junwei Zeng; Wanjiang Li; Lirong Wang; Zhipeng Hou; Yancong Feng; Hao Li; Haihong Yang; Yi-Kuen Lee; Paddy J. French; Yao Wang; Guofu Zhou;
    Journal of Colloid and Interface Science,
    Volume 649, pp. 909-917, 2023. DOI: https://doi.org/10.1016/j.jcis.2023.06.092.
    Keywords: ... 2D materials Transition metal dichalcogenides Gas sensing Patching sulfur vacancies N-doping.

    Abstract: ... Transition metal dichalcogenides (TMDCs) garner significant attention for their potential to create high-performance gas sensors. Despite their favorable properties such as tunable bandgap, high carrier mobility, and large surface-to-volume ratio, the performance of TMDCs devices is compromised by sulfur vacancies, which reduce carrier mobility. To mitigate this issue, we propose a simple and universal approach for patching sulfur vacancies, wherein thiol groups are inserted to repair sulfur vacancies. The sulfur vacancy patching (SVP) approach is applied to fabricate a MoS2-based gas sensor using mechanical exfoliation and all-dry transfer methods, and the resulting 4-nitrothiophenol (4NTP) repaired molybdenum disulfide (4NTP-MoS2) is prepared via a sample solution process. Our results show that 4NTP-MoS2 exhibits higher response (increased by 200 %) to ppb-level NO2 with shorter response/recovery times (61/82 s) and better selectivity at 25 °C compared to pristine MoS2. Notably, the limit of detection (LOD) toward NO2 of 4NTP-MoS2 is 10 ppb. Kelvin probe force microscopy (KPFM) and density functional theory (DFT) reveal that the improved gas sensing performance is mainly attributed to the 4NTP-induced n-doping effect on MoS2 and the corresponding increment of surface absorption energy to NO2. Additionally, our 4NTP-induced SVP approach is universal for enhancing gas sensing properties of other TMDCs, such as MoSe2, WS2, and WSe2.

  3. Self-Assembled Lenalidomide/AIE Prodrug Nanobomb for Tumor Imaging and Cancer Therapy
    Zhijian Mai; Nengjie Cao; Erzhuo Cheng; Zhiwen Zeng; Yancong Feng; Yao Wang; Paddy J. French; Yi-Kuen Lee; Haihong Yang; Bin Yang; Hao Li; Guofu Zhou;
    Applied Nano Materials,
    Volume 6, pp. 19807-19817, 2023. DOI: https://doi.org/10.1021/acsanm.3c03611
    Keywords: ... small-molecule prodrug, Schiff base linkage, aggregation-induced emission, self-assembly, tumor-targeted diagnosis and therapy.

    Abstract: ... To develop multifunctional small-molecule prodrugs is highly desirable for cancer treatment but remains challenging in intrinsic traceability. As an acid-cleavable linkage, a Schiff bases benefiting from its distinctive fluorescence quenching ability was selected to prepare a small-molecule prodrug with cancer-targeted and self-indicating. In this study, we designed and developed a multifunctional self-assembled nanobomb of amphiphilic TPE-Lenalidomide prodrug, which comprises a hydrophobic aggregation-induced emission (AIE) probe 4-(1,2,2- triphenylvinyl)benzaldehyde (TPE-CHO) and a hydrophilic anticancer drug Lenalidomide via a Schiff base linkage. We investigated the synergistic effect of d-PET and CN isomerization which would keep the fluorescence of TPE-Lenalidomide in the “always off” state by density functional theory (DFT) calculation. Once reaching the pathological site, such a vesicular nanobomb of TPE-Lenalidomide will be acidolyzed to release the AIE probe and Lenalidomide molecules simultaneously, consequently realizing high-efficiency effects of tumor imaging and cancer therapy (cell viability: normal cell L929, ∼79.49%; cancer cell 4T1, ∼27.08%; p = 0.000118). This work may pave an avenue to prepare small-molecule prodrugs for tumor-targeted diagnosis and cancer therapy.

  4. Carbon-Iron Electron Transport Channels in Porphyrin–Graphene Complex for ppb-Level Room Temperature NO Gas Sensing
    Yixun Gao; Jianqiang Wang; Yancong Feng; Nengjie Cao; Hao Li; Nicolaas Frans de Rooij; Ahmad Umar; Paddy J. French; Yao Wang; Guofu Zhou;
    SMALL,
    pp. 9, 2022. DOI: 10.1002/smll.202103259
    Abstract: ... It is a great challenge to develop efficient room-temperature sensing materials and sensors for nitric oxide (NO) gas, which is a biomarker molecule used in the monitoring of inflammatory respiratory diseases. Herein, Hemin (Fe (III)-protoporphyrin IX) is introduced into the nitrogen-doped reduced graphene oxide (N-rGO) to obtain a novel sensing material HNGethanol. Detailed XPS spectra and DFT calculations confirm the formation of carbon–iron bonds in HNG-ethanol during synthesis process, which act as electron transport channels from graphene to Hemin. Owing to this unique chemical structure, HNG-ethanol exhibits superior gas sensing properties toward NO gas (Ra/Rg = 3.05, 20 ppm) with a practical limit of detection (LOD) of 500 ppb and reliable repeatability (over 5 cycles). The HNG-ethanol sensor also possesses high selectivity against other exhaled gases, high humidity resistance, and stability (less than 3% decrease over 30 days). In addition, a deep understanding of the gas sensing mechanisms is proposed for the first time in this work, which is instructive to the community for fabricating sensing materials based on graphene-iron derivatives in the future.

  5. Three-Dimensional Graphene-Based Foams with “Greater Electron Transferring Areas” Deriving High Gas Sensitivity
    Zhuo Chen; Jinrong Wang; Nengjie Cao; Yao Wang; Hao Li; Nicolaas Frans de Rooij; Ahmad Umar; Yancong Feng; Paddy French; Guofu Zhou;
    Applied Nano Materials,
    Volume 4, pp. 13234-13245, 2021. DOI: https://doi.org/10.1021/acsanm.1c02759
    Keywords: ... graphene foams, supramolecular assembly, lyophilization, charge transfer, gas sensors.

    Abstract: ... Graphene foams are promising three-dimensional (3D) architectures with the combination of the intrinsic nature of graphene and unique cellular structures for various realms. Herein, a facile technique is developed by combining supramolecular assembly with lyophilization to functionalize graphene with donor−π-acceptor (D−π- A) molecules and then massively transform the two-dimensional (2D) plane nanosheets into 3D foams. The as-prepared gas sensors work at room temperature (RT) and reveal comprehensive gas sensing performance with an ultrahigh response (Ra/Rg = 3.2, 10 ppm), excellent selectivity, and reliable repeatability toward NO2. Notably, a gas sensing enhancement mechanism with density functional theory (DFT) calculations is proposed to unravel the synergetic effect of the “Greater Electron Transferring Area” and the specific 3D foam structure for the enhancement of charge transfer and NO2 adsorption. The combination of supramolecular assembly and the lyophilization technique provides a strategy to prepare 3D architectural graphene-based materials for high-performance gas sensors and chemical trace detectors.

  6. A Versatile and Efficient 0.1-to-11 Gb/s CML Transmitter in 40-nm CMOS
    Feng, Jun; Beikmirza, Mohammadreza; Mehrpoo, Mohammadreza; de Vreede, Leo C.N.; Alavi, Morteza S.;
    In 2021 18th International SoC Design Conference (ISOCC),
    pp. 41-42, 2021. DOI: 10.1109/ISOCC53507.2021.9613887

  7. First-principles investigation of the adsorption behaviors of CH 2 O on BN, AlN, GaN, InN, BP, and P monolayers
    Feng, C.; Qin, H.; Yang, D.; GuoQi Zhang;
    Materials,
    2019. DOI: 10.3390/ma12040676

  8. MIMO–monopulse target localisation for automotive radar
    R. Feng; F. Uysal; P. Aubry; A. Yarovoy;
    IET Radar, Sonar & Navigation,
    Volume 12, Issue 10, pp. 1131, August 2018. DOI: 10.1049/iet-rsn.2018.5013

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