Search or ask a question
Pricing
Login
Sign up
Home
Notebook
BETA
Literature Review
Copilot
Citation generator
Paraphraser
AI Detector
Chrome Extension
Talk with us
Use on ChatGPT
All figures (14)
Figure 2. TEM images of the Ga-Zn-oxynitrides obtained by nitridation of different precursors (Zn/Ganom=0.32). A: nitridation of the precipitate from Zn- and Ga- nitrate solution; B: nitridation of oxide mixture; C: commercial GaN. Electron diffraction patterns (inserts) reveal the presence of hexagonal wurtzite (# 76-0703).
Figure 10. Pt 4f spectra of a calcined and a used Pt/Ga-Zn-oxynitride sample obtained from nitridation of the oxide mixture. Zn/Ganom=0.14; Pt content= 1 w%.
Table 4. Characteristic binding energies and element ratios obtained from XPS measurements on the spent Pt-loaded GaN-ZnO photocatalysts Sample/co-catalyst formation Zn/Ganom Ga 3d (eV) Ga AP a (eV) N 1s (eV) N/Ga ratio O 1s (eV) Zn 2p Zn/Ga ratio Pt 4f Ga2O3, Pt calcined -- 20.2 1082.7 -- -- 531.1
Figure 11. Influence of the Pt co-catalyst formation method on the initial period of the hydrogen production reaction. The Ga-Zn-oxyinitride was obtained from oxide mixture; Zn/Ganom=0.14. Lines are only guides to the eye.
Figure 7. XRD pattern of recovered catalysts after the photocatalytic H2 production (reaction conditions in Figure 5) a=sample obtained from precipitate, co-catalyst formation by calcination; b= sample obtained from precipitate, co-catalyst formation by hydrogenation, c= sample obtained from precipitate, co-catalyst formation by hydrogenation, blank experiment, d= sample obtained from oxides, co-catalyst formation by calcination; e= sample obtained from oxides, cocatalyst formation by hydrogenation; f= GaN (commercial), co-catalyst formation by calcination, blank experiment.
Figure 8. TEM images of the Pt/Ga-Zn-oxynitride photocatalysts recovered after the photocatalytic H2 production (reaction conditions in Figure 5). A: used catalyst from precipitate, Pt co-catalyst formed by hydrogenation at 450oC; B: used catalyst from oxide mixture, Pt co-catalyst formed by hydrogenation at 450oC; C: used catalyst from precipitate, Pt co-catalyst formed by calcination at 300oC; D: used catalyst from oxide, Pt co-catalyst formed by calcination at 300oC. Consistently with XRD result, arrows in electron diffraction patterns (inserts) point to GaOOH diffractions (# 87-1901). 101 and 110 indices in C indicate hexagonal wurtzite (# 76-0703) contributions.
Table 1. Characteristic binding energies and element ratios obtained from XPS measurements on untreated Ga-Zn-oxynitride samples Sample Zn/Ganom Ga 3d (eV) Ga AP a (eV) N 1s (eV) N/GaXPS O 1s (eV) Zn 2p (eV) Zn/GaXPS Ga2O3 -- 20.5 1082.7 -- -- 531.4
Figure 3. XRD patterns of the Pt loaded Ga-Zn-oxynitrides after different treatments of the Pt precursor. a= nitrided precipitate, Pt formation by calcination; b= nitrided precipitate, calcination after “blank” impregnation (impregnation with no Pt precursor in the solution); c= nitrided precipitate, calcination without impregnation; d= nitrided precipitate, Pt formation by hydrogenation; e= nitrided oxides, Pt formation by calcination; f= nitrided oxides, Pt formation by hydrogenation g= GaN (commercial), Pt formation by calcination. Zn/Ganom: a-d=0.32, e-f=0.14, Pt load (when applicable) = 1%.
Figure 5. Pt 4f spectra of an impregnated, a hydrogen treated and a calcined Pt/Ga-Znoxynitride sample obtained from nitridation of the precipitate. Zn/Ganom=0.14; Pt content= 1 w%.
Table 3. Characteristic binding energies and element ratios obtained from XPS measurements on 1% Pt-loaded Ga-Zn-oxynitride samples Sample/co-catalyst formation Zn/Ganom Ga 3d (eV) Ga AP a (eV) N 1s (eV) N/Ga ratio O 1s (eV) Zn 2p Zn/Ga ratio Pt 4f GaN, Pt calcined - 20.1 1083.4 397.6 0.49 530.9
Figure 12. Evolution of the investigated samples during their lifetime.
Figure 9. O 1s spectra of the reduced and used Pt/GaN-ZnO photocatalysts derived from precipitates (Zn/Ganom=0.32). Top line: reduced, before the photocatalytic reaction; bottom spectrum: the same sample recovered after the photocatalytic reaction
Figure 1. XRD patterns of the Ga-Zn-oxynitrides obtained by nitridation of different precursors. a= sample obtained by nitridation of the precipitate from Zn(NO3)2 and Ga(NO3)3 with Zn/Ganom=0.32 (corundum internal standard added); b= sample obtained by nitridation of the precipitate from Zn(NO3)2 and Ga(NO3)3 with Zn/Ganom=0.14 (corundum internal standard added); c= sample obtained by nitridation of oxide mixture with Zn/Ganom=0.32; d= sample obtained by nitridation of oxide mixture with Zn/Ganom=0.14; e= GaN (commercial)
Figure 4. TEM images of the Pt/Ga-Zn-oxynitrides (Zn/Ganom=0.32) obtained by different formation of Pt co-catalyst. A: sample from precipitate, Pt co-catalyst formed by hydrogenation at 450oC; B: sample from oxide mixture, Pt co-catalyst formed by hydrogenation at 450oC; C: sample from precipitate, Pt co-catalyst formed by calcination at 300oC; D: sample from oxide, Pt co-catalyst formed by calcination at 300oC. Consistently with XRD result, electron diffraction patterns (inserts) revealed the presence of hexagonal wurtzite (# 76-0703) and for C GaOOH diffractions (# 87-1901), which are indicated by arrows.
Journal Article
•
DOI
•
Structural evolution in Pt/Ga-Zn-oxynitride catalysts for photocatalytic reforming of methanol
[...]
ÿdám Vass
1
,
Zoltán Pászti
1
,
Szabolcs Bálint
1
,
Péter Németh
1
,
Gábor P. Szijjártó
1
,
András Tompos
1
,
Emília Tálas
1
- Show less
+3 more
•
Institutions (1)
Hungarian Academy of Sciences
1
01 Nov 2016
-
Materials Research Bulletin