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Aravind, K, Su YW, Chun DS, Kuo W, Wu CS, Chang-Liao KS, Chen KH, Chen LC, Chen CD.  2012.  Magnetic-field and temperature dependence of the energy gap in InN nanobelt. AIP Advances. 2:012155.
Su, YW, Aravind K, Wu CS, Kuo W, Chen KH, Chen LC, Chang-Liao KS, Su WF, Chen CD.  2009.  Magnetoresistance fluctuations in a weak disorder indium nitride nanowire. J. Phys. D: Appl. Phys.. 42:185009.
Chien, SC, Chattopadhyay* S, Chen LC, Lin ST, Chen KH.  2003.  Mechanical properties of amorphous boron carbon nitride films produced by dual gun sputtering. Diamond Relat. Mater. . 12:1463-1471.
Shen, ZH, Hess* P, Huang JP, Lin YC, Chen KH, Chen LC, Lin ST.  2006.  Mechanical properties of nanocrystalline diamond films. J. Appl. Phys.. 99:124302-(1-6).
Dhara*, S, Lu C-Y, Nair KGM, Chen KH, Chen C-P, Huang Y-F, David C, Chen LC, Raj B.  2008.  Mechanism of bright red emission in Si nanoclusters. Nanotechnology. 19:395401-(1-5).
Chen, CH, Chen YF, Lan ZH, Chen LC, Chen KH, Jiang HX, Lin JY.  2004.  Mechanism of enhanced luminescence in InxAlyGa1–x–yN quaternary epilayers. Appl. Phys. Lett.. 84:1480-1482.
Yang, HC, Kuo PF, Lin TY, Chen YF, Chen KH, Chen LC, Chyi JI.  2000.  Mechanism of luminescence in InGaN multiple quantum wells. Appl. Phys. Lett.. 76:3712-3714.
S. Dhara, Datta A, Wu CT, Chen* KH, Wang YL, Muto S, Tanabe T, Shen CH, Hsu CW, Chen LC, Maruyama T.  2005.  Mechanism of nanoblister formation in Ga+ self-ion implanted GaN nanowires. Appl. Phys. Lett.. 86:203119-(1-3).
Das, CR, Dhara S, Hsu HC, Chen LC, Jeng YR, Bhaduri AK, Raj B, Chen KH, Albert SK.  2009.  Mechanism of recrystallization process in epitaxial GaN under dynamic stress field : Atomistic origin of planar defect formation. J. Raman Spect.. 40:1881-1884.
Billo, T, Shown I, kumar Anbalagan A, Effendi TA, Sabbah A, Fu F-Y, Chu C-M, Woon W-Y, Chen R-S, Lee C-H, Chen K-H, Chen L-C.  2020.  A mechanistic study of molecular CO2 interaction and adsorption on carbon implanted SnS2 thin film for photocatalytic CO2 reduction activity, 2020. 72:104717. AbstractWebsite

Gas-phase photocatalytic reactions to convert carbon dioxide and water into oxygen and hydrocarbons are the foundation of life on earth. However, the efficiency of photosynthesis is relatively low (~1%), which leaves much room for artificial photosynthesis to reach the benchmark of the solar cells (>15%). In this work, carbon implanted SnS2 thin films (C–SnS2) were prepared to study photocatalytic activity and adsorbate-catalyst surface interactions during CO2 photoreduction. The electron density distribution in C–SnS2 and its contribution toward the photogenerated charge transfer process has been analyzed by the angle-dependent X-ray absorption near-edge structure (XANES) study. The C–SnS2 surface affinity toward the CO2 molecule was monitored by in-situ dark current and Raman spectroscopy measurements. By optimizing the dose during ion implantation, SnS2 thin film with 1 wt% carbon incorporation shows 108 times enhancement in the CO2 conversion efficiency and more than 89% product selectivity toward CH4 formation compared with the as-grown SnS2 without carbon incorporation. The improved photocatalytic activity can be ascribed to enhanced light harvesting, pronounced charge-transfer between SnS2 and carbon with improved carrier separation and the availability of highly active carbon sites that serve as favorable CO2 adsorption sites.

Hwang, JY, Chatterjee A, Shen CH, Wang JH, Sun CL, Chyan O, Chen CW, Chen KH, Chen* LC.  2009.  Mesoporous active carbon dispersed with ultra-fine platinum nanoparticles and their electrochemical properties. Diamond Relat. Mater.. 18:303-306.
Kamal Hussien, M, Sabbah A, Qorbani M, Hammad Elsayed M, Raghunath P, Lin T-Y, Quadir S, Wang H-Y, Wu H-L, Tzou D-LM, Lin M-C, Chung P-W, Chou H-H, Chen L-C, Chen K-H.  2021.  Metal-free four-in-one modification of g-C3N4 for superior photocatalytic CO2 reduction and H2 evolution, 2021. Chemical Engineering Journal. :132853. AbstractWebsite

Utilization of g-C3N4 as a single photocatalyst material without combination with other semiconductor remains challenging. Herein, we report a facile green method for synthesizing a metal free modified g-C3N4 photocatalyst. The modification process combines four different strategies in a one-pot thermal reaction: non-metal doping, porosity generation, functionalization with amino groups, and thermal oxidation etching. The as-prepared amino-functionalized ultrathin nanoporous boron-doped g-C3N4 exhibited a high specific surface area of 143.2 m2 g−1 which resulted in abundant adsorption sites for CO2 and water molecules. The surface amino groups act as Lewis basic sites to adsorb acidic CO2 molecules, which can also serve as active sites to facilitate hydrogen generation. Besides, the simultaneous use of ammonium chloride as a dynamic gas bubble template along with thermal oxidation etching efficiently boosts the delamination of the g-C3N4 layers to produce ultrathin sheets; this leads to stronger light–matter interactions and efficient charge generation. Consequently, the newly modified g-C3N4 achieved selective gas-phase CO2 reduction into CO with a production yield of 21.95 µmol g-1, in the absence of any cocatalyst. Moreover, a high hydrogen generation rate of 3800 µmol g-1 h-1 and prominent apparent quantum yield of 10.6% were recorded. This work opens up a new avenue to explore different rational modifications of g-C3N4 nanosheets for the efficient production of clean energy.

Wen, CY, Wu JJ, Lo HJ, Chen LC, Chen KH, Lin ST, Yu Y-C, Wang C-W, Lin E-K.  2000.  Methylamine growth of SiCN films using ECR-CVD. Mat. Res. Soc. Symp.. :606,115-120.
Chen, KH, Lai YL, Lin JC, Song KJ, Chen LC, Huang CY.  1995.  Micro-Raman for Diamond Film Stress Analysis. Diamond and Related Materials. 4:460.
Venugopal, B, Shown I, Samireddi S, Syum Z, Krishnamoorthy V, Wu H-L, Chu C-W, Lee C-H, Chen L-C, Chen K-H.  2021.  Microstructural intra-granular cracking in Cu2ZnSnS4@C thin-film anode enhanced the electrochemical performance in lithium-ion battery applications, 2021. Materials Advances. 2(17):5672-5685.: RSC AbstractWebsite

Cu2ZnSnS4 (CZTS) has demonstrated excellent performance as an anode material for lithium-ion batteries. However, the repeated lithiation and delithiation create a cracking pattern and lead to island formation in the thin-film electrode, resulting in a capacity fading over cycling in lithium-ion batteries (LIB's). In order to control this crack behaviour, we introduce carbon into CZTS thin-films by a hydrothermal method to form CZTS@C composite. CZTS@C significantly reduced the crack pattern formation on the electrode surface as well as improved the conductivity of the CZTS@C electrode. At the early stages of lithiation and delithiation, the volume expansion and contraction of Li–CZTS@C create intra-granular cracking only at the surface level, and it offers a high capacity of about 785 mA h g−1 after 150 cycles at 1000 mA g−1 charging rate, excellent rate capability (942 mA h g−1, 678 mA h g−1 and 435 mA h g−1 at 500 mA g−1, 2000 mA g−1 and 5000 mA g−1), and superior cyclability (925 mA h g−1 even after 200 cycles at 500 mA g−1). The excellent electrochemical performance at high-current rates can be attributed to intra-granular cracking together with carbon coating that provides a short transportation length for both lithium ions and electrons. Moreover, the controlled cracking pattern formation in CZTS@C facilitates faster reaction kinetics, which open up a new solution for the development of high-power thin-film anodes for next-generation LIBs applications.

Howlader, S, Vasudevan R, Jarwal B, Gupta S, Chen K-H, Sachdev K, Banerjee MK.  2020.  Microstructure and mechanical stability of Bi doped Mg2Si0.4Sn0.6 thermoelectric material, 2020. 818:152888. AbstractWebsite

Bi doped Mg2Si0.4Sn0.6 had been synthesised in a high energy ball mill followed by compaction using a sintering hot press. The structural and compositional characterization of sintered mass indicated the formation of a highly densified single-phase product. The microstructure of the hot-pressed samples had been critically assessed. Thermoelectric properties were measured between room temperature and 723 K. A decrease in electrical conductivity was found with the increase in temperature but the Seebeck coefficient showed a reverse trend justifying the attainment of degenerate semiconducting behaviour. Meanwhile, the lattice thermal conductivity was subdued to 1.5 W/mK at 623 K. However, the highest zT value of 0.8 was achieved at 723 K. Moreover, the detailed X-ray photoelectron spectroscopic analysis was carried for the determination of binding energy of the constituent elements in the experimental alloy; it also provided the correct estimation of atomic percentage of the concerned elements. The Raman spectrum revealed a shift in F2g peak with respect to that of Mg2Sn and Mg2Si in correspondence with the composition of the synthesised alloy. The synthesised alloy showed micro and nano hardness of 3.7 and 4.03 GPa respectively, which implies that good mechanical strength could be achieved in the synthesised alloy.

Lin, YG, Hsu YK, Lin YK, Chen SY, Chen LC, Chen* KH.  2011.  Microwave-activated CuO nanotip/ZnO nanorod nanoarchitectures embedded in a microreactor for efficient hydrogen production. J. Mater. Chem.. 21:324-326.
Muthusamy, S, Sabhapathy P, Raghunath P, Sabbah A, Chang Y-C, Krishnamoorthy V, Ho T-T, Chiou J-W, Lin M-C, Chen L-C, Chen K-H.  2023.  Mimicking Metalloenzyme Microenvironments in the Transition Metal-Single Atom Catalysts for Electrochemical Hydrogen Peroxide Synthesis in an Acidic Medium, 2023. Small Methods. :2300234.: John Wiley & Sons, Ltd AbstractWebsite

Abstract Electrochemical reduction of oxygen into hydrogen peroxide in an acidic medium offers an energy-efficient and green H2O2 synthesis as an alternative to the energy-intensive anthraquinone process. Unfortunately, high overpotential, low production rates, and fierce competition from traditional four-electron reduction limit it. In this study, a metalloenzyme-like active structure is mimicked in carbon-based single-atom electrocatalysts for oxygen reduction to H2O2. Using a carbonization strategy, the primary electronic structure of the metal center with nitrogen and oxygen coordination is modulated, followed by epoxy oxygen functionalities close to the metal active sites. In an acidic medium, CoNOC active structures proceed with greater than 98% H2O2 selectivity (2e?/2H+) rather than CoNC active sites that are selective to H2O (4e?/4H+). Among all MNOC (M = Fe, Co, Mn, and Ni) single-atom electrocatalysts, the CoNOC is the most selective (> 98%) for H2O2 production, with a mass activity of 10 A g?1 at 0.60 V vs. RHE. X-ray absorption spectroscopy is used to identify the formation of unsymmetrical MNOC active structures. Experimental results are also compared to density functional theory calculations, which revealed that the structure-activity relationship of the epoxy-surrounded CoNOC active structure reaches optimum (?G*OOH) binding energies for high selectivity.

Muthusamy, S, Sabbah A, Sabhapathy P, Chang Y-C, Billo T, Syum Z, Chen L-C, Chen K-H.  2023.  Modification of Conductive Carbon with N-Coordinated Fe−Co Dual-Metal Sites for Oxygen Reduction Reaction, 2023. ChemElectroChem. n/a(n/a):e202300272.: John Wiley & Sons, Ltd AbstractWebsite

Abstract Earth-abundant commercial conductive carbon materials are ideal electrocatalyst supports but cannot be directly utilized for single-atom catalysts owing to the lack of anchoring sites. Therefore, we employed crosslink polymerization to modify the conductive carbon surface with Fe?Co dual-site electrocatalysts for oxygen reduction reaction (ORR). First, metal-coordinated polyurea (PU) aerogels were prepared using via crosslinked polymerization at ambient temperature. Then, carbon-supported, atomically dispersed Fe?Co dual-atom sites (FeCoNC/BP) were formed by high-temperatures pyrolysis with a nitrogen source. FTIR and 13C NMR measurements showed PU linkages, while 15N NMR revealed metal?nitrogen coordination in the PU gels. Asymmetric, N-coordinated, and isolated Fe?Co active structures were found after pyrolysis using XAS and STEM. In alkaline media, FeCoNC/BP exhibited excellent ORR activity, with a E1/2 of 0.93?V vs. RHE, higher than that of Pt/C (20?%) (0.90?V), FeNC/BP (0.88?V), and CoNC/BP (0.85?V). An accelerated durability test (ADT) on FeCoNC/BP indicated good durability over 35000 cycles. FeCoNC/BP also showed moderate ORR and ADT performance in acidic media. The macro/mesoporous N-doped carbon structures enhanced the mass transport properties of the dual Fe?Co active-sites. Therefore, modifying carbon supports with nonprecious metal catalysts may be a cost-effective-strategy for sustained electrochemical energy conversion.

Ho, T-T, Yang Z-L, Fu F-Y, Jokar E, Hsu H-C, Liu P-C, Quadir S, Cheng-YingChen, Chiu Y-P, Wu C-I, Chen K-H, Chen L-C.  2022.  Modulation and Direct Mapping of the Interfacial Band Alignment of an Eco-Friendly Zinc-Tin-Oxide Buffer Layer in SnS Solar Cells, 2022. ACS Applied Energy MaterialsACS Applied Energy Materials. 5(11):14531-14540.: American Chemical Society AbstractWebsite
Chattopadhyay*, S, Shi SC, Lan ZH, Chen CF, Chen KH, Chen LC.  2005.  Molecular sensing with ultrafine silver crystals on hexagonal aluminum nitridenanorodtemplate. J. Am. Chem. Soc.. 127:2820-2821.
Chen, RS, Lu CY, Chen KH, Chen LC.  2009.  Molecule-modulated photoconductivity and gain-amplified selective gas sensing in polar GaN nanowires. Appl. Phys. Lett.. 95:233119.
Chen, HM, Chen CK, Chang YC, Tsai CW, Liu RS, Hu SF, Chang WS, Chen KH.  2010.  Monolayer-quantum dots sensitized ZnO nanowires-array photoelectrodes: true efficiency for water splitting. Angew. Chem. Int. Ed.. 49:5966-5969.
Hsu, CH, Huang YF, Chen LC, Chattopadhyay* S, Chen KH, Lo HC, Chen CF.  2006.  Morphology control of Si nanotips fabricated by electron cyclotron resonance plasma etching. J. Vac. Sci. Technol. . B24:308-311.
Chen, HM, Chen CK, Lin CC, Liu RS, Yang H, Chang WS, Chen KH, Chan TS, Lee JF, Tsai DP.  2011.  Multi-bandgap-sensitized ZnO nanorod photoelectrode arrays for water splitting: an X-ray absorption spectroscopy approach for the electronic evolution under solar illumination. J. Phys. Chem. C. 115:21971-21980.