Structural and electrical characterisation of PtS from H2S-converted Pt

Monaghan, Scott; Coleman, E.; Ansari, Lida; Lin, Jun; Buttimer, Alexandra; Coleman, Patrick A.; Connolly, J.P.; Povey, Ian M.; Kelleher, Bryan; Coileáin, Cormac Ó; McEvoy, Niall; Hurley, Paul K.; Gity, Farzan

doi:10.1016/j.apmt.2021.101163

Cited by 8 publications

(7 citation statements)

References 37 publications

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“… 45 Recently, a DFT study was conducted to calculate cooperite band gaps using GGA and the Heyd–Scuseria–Ernzerhof hybrid functional (HSE06), where band gaps of 0.43 and 1.58 eV were found, respectively. 46 As expected, a larger band gap was obtained with the HSE06 approach. It is clear that experiments, TB-LMTO, and DFT using HSE06 established that cooperite had a wide band gap and was a semiconductor.…”

Section: Computational Methodssupporting

confidence: 78%

“…Furthermore, the experimental studies reported a band gap of ∼1.41 eV using X-ray diffraction, and band gaps of 0.8 and 1.40 eV were reported using the absorption curve from X-ray diffraction and diffuse reflectance measurement for cooperite . Recently, a DFT study was conducted to calculate cooperite band gaps using GGA and the Heyd–Scuseria–Ernzerhof hybrid functional (HSE06), where band gaps of 0.43 and 1.58 eV were found, respectively . As expected, a larger band gap was obtained with the HSE06 approach.…”

Section: Computational Methodsmentioning

confidence: 99%

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Reconstruction of Cooperite (PtS) Surfaces: A DFT-D+U Study

Mkhonto

Ngoepe

2022

ACS Omega

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Cooperite (PtS) is one of the main sources of platinum in the world and has not been given much attention, in particular from the computational aspect. Besides, the surface stability of cooperite is not fully understood, in particular the preferred surface cleavage. In the current study, we employed computer modeling methods within the plane-wave framework of density functional theory with dispersion correction and the U parameter to correctly predict the bulk and surface properties. We reconstructed and calculated the geometries and surface energies of (001), (100), (101), (112), (110), (111), and (211) cooperite surfaces of stoichiometric planes. The Pt d-orbitals with U = 4.5 eV and S p-orbitals with U = 5.5 eV were found optimum to correctly predict a band gap of 1.408 eV for the bulk cooperite model, which agreed with an experimental value of 1.41 eV. The PtS-, Pt-, and S-terminated surfaces were investigated. The structural and electronic properties of the reconstructed surfaces were discussed in detail. We observed one major mechanism of relaxation of cooperite surface reconstructions that emerged from this study, which was the formation of Pt–Pt bonds. It emanated that the (110) and (111) cooperite surfaces underwent significant reconstruction in which the Pt2+ cation relaxed into the surface, forming new Pt–Pt (Pt2 2+) bonds. Similar behavior was perceived for (101) and (211) surfaces, where the Pt2+ cation relaxed inward and sideways on the surface, forming new Pt–Pt (Pt2 2+) bonds. The surface stability decreased in the order (101) > (100) ≈ (112) > (211) > (111) > (110) > (001), indicating that the (101) surface was the most stable, leading to an octahedron cooperite crystal morphology with truncated corners under equilibrium conditions. However, the electronic structures indicated that the chemical reactivity stability of the surfaces would be determined by band gaps. It was found that the (112) surface had a larger band gap than the other surfaces and thus was a chemical stability competitor to the (101) surface. In addition, it was established that the surfaces had different reactivities, which largely depended on the atomic coordination and charge state based on population atomic charges. This study has shown that cooperite has many planes/surface cleavages as determined by the computed crystal morphology, which is in agreement with experimental X-ray diffraction (XRD) pattern findings and the formation of irregular morphology shapes.

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Section: Computational Methodssupporting

confidence: 78%

Section: Computational Methodsmentioning

confidence: 99%

Reconstruction of Cooperite (PtS) Surfaces: A DFT-D+U Study

Mkhonto

Ngoepe

2022

ACS Omega

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“…Hydrogen sulfide (H 2 S) is one of the main pollutants in the atmosphere with colorless and highly toxic properties and is usually produced during industrial processes such as coal mines, oil, and sewage treatment plants. Trace amounts of H 2 S gas exposure can be detrimental to human health, so effective and accurate detection of H 2 S gas in the environment is of great significance. − Resistive gas sensors are one of the most researched and widely used H 2 S monitoring devices due to their simplicity of operation, compactness, and robustness . ZnO is one of the most widely used n-type semiconductors, and there are many ZnO-based materials reported in the literature for gas detection.…”

Section: Introductionmentioning

confidence: 99%

Engineering a Heterophase Interface by Tailoring the Pt Coverage Density on an Amorphous Ru Surface for Ultrasensitive H₂S Detection

et al. 2023

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Amorphous/crystalline heterophase engineering is emerging as an attractive strategy to adjust the properties and functions of nanomaterials. Here, we reveal a heterophase interface role by precisely tailoring the crystalline Pt coverage density on an amorphous Ru surface (cPt/aRu) for ultrasensitive H 2 S detection. We found that when the atomic ratio of Pt/Ru increased from 10 to 50%, the loading modes of Pt changed from island coverage (1cPt/aRu) to cross-linkable coverage (3cPt/aRu) and further to dense coverage (5cPt/aRu). The differences in coverage models further regulate the chemical adsorption of H 2 S on Pt and the electronic transformation process on Ru, which can be proved by ex situ X-ray photoelectron spectroscopy experiments. Notably, a special crosslinkable coverage 3cPt/aRu on ZnO shows the best gas-sensitive performance, in which the operating temperature reduces from 240 to 160 °C compared with pristine ZnO and the selectivity coefficient for H 2 S gas improves from ∼1.2 to ∼4.6. This is mainly benefit from the maximized exposure of the amorphous/crystalline heterophase interface. Our work thus provides a new platform for future applications of amorphous/crystalline heterogeneous nanostructures in gas sensors and catalysis.

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“…First, the chemical vapor transport technique leads to formation of bulk crystals of PtS 2 , 35,37–39 in which the confined space of the sealed ampoule facilitates a high partial pressure of S vapor. In contrast, the open-space sintering of mixed Pt/S powders results in the synthesis of PtS crystals 40–44 in the early stage or the sulfurization of Pt metal, 20,45,46 which provided PtS powders for the XRD investigation to obtain the standard diffraction pattern data. By the tuning of S partial pressure during the annealing, one can convert PtS into PtS 2 .…”

Section: Introductionmentioning

confidence: 99%