Ultrananocrystalline diamond films as a high QE photocathode

Baryshev, Sergey V.; Antipov, Sergey; Jing, Chunguang; Quintero, Kenneth J. Pérez; Sumant, Anirudha V.

doi:10.1063/1.4965658

Cited by 3 publications

(2 citation statements)

References 10 publications

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“…Our calculations show that UNCD has a relatively low work function (3.35 eV, Figure S1) and thus easily gives electrons to the metal oxide clusters. Note that the experimental value of the work function is 3.3 eV for nanocrystalline diamond − and 3.6 eV for nitrogen-doped UNCD . The Bader charge analysis shows that the total charge on the cluster in Cu 5 O 3 /UNCD and Cu 5 O 5 /UNCD can be up to −1.69 and −3.50 e , respectively, with the charge on Cu varying from −0.14 to 0.76 e .…”

Section: Results and Discussionmentioning

confidence: 94%

“…Note that the experimental value of the work function is 3.3 eV for nanocrystalline diamond 80−83 and 3.6 eV for nitrogen-doped UNCD. 84 The Bader charge analysis shows that the total charge on the cluster in Cu 5 O 3 / UNCD and Cu 5 O 5 /UNCD can be up to −1.69 and −3.50e, respectively, with the charge on Cu varying from −0.14 to 0.76e. 79 Bader charge analysis shows that the average charge of Cu in the Cu 5 O 3 isomers is 0.49, 0.28, and 0.26e, and in the Cu 5 O 5 isomers it is 0.62, 0.38, and 0.35e, respectively.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

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Interpreting the Operando XANES of Surface-Supported Subnanometer Clusters: When Fluxionality, Oxidation State, and Size Effect Fight

et al. 2020

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X-ray absorption near edge structure (XANES) spectroscopy is widely used for operando catalyst characterization. We show that, for highly fluxional supported nanoclusters, the customary extraction of the oxidation state of the metal from the XANES data by fitting to the bulk standards is highly questionable. The XANES signatures, as well as the apparent oxidation state for such clusters arise from a complex combination of many factors, and not only from the chemical composition in reaction conditions (e.g. oxygen content in oxidizing astrosphere). The thermallyaccessible isomerization and population of several structurally distinct cluster forms, clustersupport interaction, and intrinsic size effects all impact the metal oxidation state and XANES signal. We demonstrate this on copper oxide clusters with different compositions, Cu4Ox(x = 2-5) and Cu5Oy (y = 3, 5), deposited on amorphous alumina and ultrananocrystalline diamond (UNCD), for which we computed the XANES spectra and compare the results to the experiment. We show in addition that fitting the experimental spectrum to calculated spectra of supported clusters can in contrast provide good agreement and insight on the spectrum-composition-structure relation. Experimental XANES interpreted using the proposed fitting scheme shows the partial reduction of Cu oxide clusters at rising temperatures, and pinpoints the specific stoichiometries that dominate in the ensemble of cluster states as the temperature changes.

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