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
AbstractAbstract 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
AbstractAbstract 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
Abstractn/a
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.
Qorbani, M, Chou T-chin, Lee Y-H, Samireddi S, Naseri N, Ganguly A, Esfandiar A, Wang C-H, Chen L-C, Chen K-H, Moshfegh AZ.
2017.
Multi-porous Co3O4 nanoflakes @ sponge-like few-layer partially reduced graphene oxide hybrids: towards highly stable asymmetric supercapacitors. Journal of Materials Chemistry A. 5:12569-12577.
Roy, PK, Haider G, Lin H-I, Liao Y-M, Lu C-H, Chen K-H, Chen L-C, Shih W-H, Liang C-T, Chen Y-F.
2018.
Multicolor Ultralow-Threshold Random Laser Assisted by Vertical-Graphene Network, 2018. Advanced Optical MaterialsAdvanced Optical Materials. 6(16):1800382.: John Wiley & Sons, Ltd
AbstractAbstract Application of lasers is omnipresent in modern-day technology. However, preparation of a lasing device usually requires sophisticated design of the materials and is costly, which may limit the suitable choice of materials and the lasing wavelengths. Random lasers, on the other hand, can circumvent the aforementioned shortcomings with simpler fabrication process, lower processing cost, material flexibility for any lasing wavelengths with lower lasing threshold, providing a roadmap for the design of super-bright lighting, displays, Li-Fi, etc. In this work, ultralow-threshold random laser action from semiconductor nanoparticles assisted by a highly porous vertical-graphene-nanowalls (GNWs) network is demonstrated. The GNWs embedded by the nanomaterials produce a suitable cavity for trapping the optical photons with semiconductor nanomaterials acting as the gain medium. The observed laser action shows ultralow values of threshold energy density ≈10 nJ cm?2 due to the strong photon trapping within the GNWs. The threshold pump fluence can be further lowered to ≈1 nJ cm?2 by coating Ag/SiO2 upon the GNWs due to the combined effect of photon trapping and strong plasmonic enhancement. In view of the growing demand of functional materials and novel technologies, this work provides an important step toward realization of high-performance optoelectronic devices.
S. Dhara*, KH, Chandra S, Mangamma G, Kalavathi S, Shankar P, Nair KGM, Tyagi AK, Hsu CW, Kuo CC, Chen LC, Chen KH, Sriram KK.
2007.
Multiphonon Raman scattering in GaN nanowires. Appl. Phys. Lett.. 90:213104.