Browsing by Author "Chen, Jing-Han"

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    Bifunctional metal phosphide FeMnP films from single source metal organic chemical vapor deposition for efficient overall water splitting
    (Elsevier, 2017) Zhao, Zhenhuan; Schipper, Desmond E.; Leitner, Andrew P.; Thirumalai, Hari; Chen, Jing-Han; Xie, Lixin; Qin, Fan; Alam, Md Kamrul; Grabow, Lars C.; Chen, Shuo; Wang, Dezhi; Ren, Zhifeng; Wang, Zhiming; Whitmire, Kenton H.; Bao, Jiming
    Developing stable and efficient bifunctional catalysts for overall water splitting into hydrogen and oxygen is a critical step in the realization of several clean-energy technologies. Here we report a robust and highly active electrocatalyst that is constructed by deposition of the ternary metal phosphide FeMnP onto graphene-protected nickel foam by metal-organic chemical vapor deposition from a single source precursor. FeMnP exhibits high electrocatalytic activity toward both the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER). Utilizing FeMnP/GNF as both the anode and the cathode for overall water splitting, a current density of 10 mA cm−2 is achieved at a cell voltage of as low as 1.55 V with excellent stability. Complementary density functional theory (DFT) calculations suggest that facets exposing both Fe and Mn sites are necessary to achieve high HER activity. The present work provides a facile strategy for fabricating highly efficient electrocatalysts from earth-abundant materials for overall water splitting.
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    Iron carbonyl clusters with ECl2 units (E = P, As)
    (Elsevier, 2017) Schipper, Desmond E.; Chen, Jing-Han; Whitmire, Kenton H.
    Reaction of [PPN][HFe(CO)4] (PPN = bis(triphenylphosphine)iminium) with PCl3 in a 1:1 ratio produced small amounts of [PPN][P{Fe(CO)4}2Cl2] ([PPN][Ia]). Reaction of [Et4N][HFe(CO)4] with AsCl3 in a 1:0.75 ratio in THF at −78 °C produced [Et4N][As{Fe(CO)4}2Cl2] ([PPN][Ib]) as the majority product. The compound [PPN][(CO)4FePCl2O] ([PPN][II]) was obtained from the reaction of Fe2(CO)9 with PCl3 in THF. In contrast, [Et4N][HFe(CO)4] reacted with PCl3 at −78 °C in a 2:1 ratio to yield [Et4N][Fe2(CO)6{(μ4-PFe(CO)4)2(μ-CO)}{μ-PCl2}] ([Et4N][III]) as the majority product. The compounds were characterized spectroscopically and by single-crystal X-ray diffraction analyses.
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    Thin Films of (Fe1–xCox)3P and Fe3(P1–xTex) from the Co-Decomposition of Organometallic Precursors by MOCVD
    (American Chemical Society, 2016) Leitner, Andrew P.; Chen, Jing-Han; Schipper, Desmond E.; Whitmire, Kenton H.
    A new method for preparing thin films of ternary transition metal phosphides has been developed. The ferromagnetic compound Fe3P has been doped with cobalt and tellurium by decomposing H2Fe3(CO)9PtBu with either Co3(CO)9PtBu or H2Fe3(CO)9Te via metal–organic chemical vapor deposition (MOCVD) onto a quartz substrate. Solid mixtures of the organometallic clusters were vaporized and decomposed at 400 °C to produce films that were subsequently annealed under vacuum at 650 °C for 24 h to afford crystalline films of (Fe1–xCox)3P (0.09 < x < 0.22) and Fe3(P1–xTex) (0.04 < x < 0.42). The films exhibit phase purity as confirmed by powder X-ray diffraction and X-ray photoelectron spectroscopy, which also confirmed the homogeneity of the films. Changes in elemental ratios were tracked by unit cell constants and ICP-OES analysis. Field-dependent magnetization measurements showed magnetic hysteresis with similar magnetic saturation values for each doped material. Thermogravimetric analysis was used to compare the Curie temperatures (Tc) of pristine Fe3P (thin film) and the doped films; Co-doping was found to lower the Tc by up to 7 °C and Te-doping had no observable effect on the Tc.