Valiyaveettil, SM, Nguyen D-L, Wong DP, Hsing C-R, Paradis-Fortin L, Qorbani M, Sabbah A, Chou T-L, Wu K-K, Rathinam V, Wei C-M, Chen L-C, Chen K-H.
2022.
Enhanced Thermoelectric Performance in Ternary Skutterudite Co(Ge0.5Te0.5)3 via Band Engineering, 2022. Inorganic Chemistry. : American Chemical Society
Abstract
Valiyaveettil, SM, Qorbani M, Hsing C-R, Chou T-L, Paradis-Fortin L, Sabbah A, Srivastava D, Nguyen D-L, Ho T-T, Billo T, Ganesan P, Wei C-M, Chen L-C, Chen K-H.
2022.
Enhanced thermoelectric performance of skutterudite Co1−yNiySn1.5Te1.5−x with switchable conduction behavior, 2022. Materials Today Physics. 28:100889.
AbstractA fine control of carriers in solids is the most essential thing while exploring any functionality. For a ternary skutterudite like CoSn1·5Te1.5−x, which has been recently recognized as a potential material for thermoelectric conversion, the dominant carrier could be either electrons or holes via chemically tuning the quaternary Sn2Te2 rings in the structure. Both theoretical calculation and different spectroscopic probes, such as X-ray photoelectron spectroscopy (XPS) and X-ray absorption spectroscopy (XAS) were employed to unveil the conduction type switching details. On the other hand, a Ni-for-Co substitution was applied to enhance electronic transport, and thereby the thermoelectric power factor. Thanks to the substantial cut-off of lattice thermal conductivity by the characteristic Sn2Te2 rings in the skutterudite structure, ultimately a 70-fold increase in the dimensionless figure-of-merit (zT) is achieved at 723 K with the nominal composition Co0·95Ni0·05Sn1·5Te1.5.
Venugopal, B, Syum Z, Yu S-Y, Sabbah A, Shown I, Chu C-W, Chen L-C, Lee C-H, Wu H-L, Chen K-H.
2022.
Enhancing the Areal Capacity and Stability of Cu2ZnSnS4 Anode Materials by Carbon Coating: Mechanistic and Structural Studies During Lithiation and Delithiation, 2022. ACS Omega. 7(11):9152-9163.: American Chemical Society
Abstract
Ho, T-T, Jokar E, Quadir S, Chen R-S, Liu F-C, Cheng-YingChen, Chen K-H, Chen L-C.
2022.
Enhancing the photovoltaic properties of SnS-Based solar cells by crystallographic orientation engineering, 2022. Solar Energy Materials and Solar Cells. 236:111499.
AbstractTin monosulfide (SnS) is a promising light-harvesting material for solar cell applications, owing to its potential for large-scale production, cost-effectiveness, eco-friendly source materials, and long-term stability. However, SnS crystallizes in an orthorhombic structure, which results in a highly anisotropic charge transport behavior. Tailoring the crystallographic orientation of the SnS absorber layer plays a critical role in the enhancement of the transfer of charge carriers and the power conversion efficiency (PCE). By controlling the substrate tilting angle and temperature ramp rate in vapor transport deposition, the crystal growth orientation was tuned to a preferred direction which significantly suppressed the unfavorable (040) crystallographic plane. Through the combination of these two approaches, the PCE could be increased from 0.11% to 2%. The effect of the tilting angle was numerically simulated to investigate its role in controlling the film uniformity and directing the film growth. In addition, the correlation between the texture coefficient of the (040) plane and the charge transport properties was determined by a combination of analytical methods such as device performance studies, electrochemical impedance spectroscopy, along with transient photovoltage, space-charge-limited current, and dark current measurements. These techniques were blended together to prove that the marked improvement in PCE can be ascribed to a reduced charge recombination (in both SnS bulk and interfaces) and an enhanced hole mobility.
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
Fu, F-Y, Fan C-C, Qorbani M, Huang C-Y, Kuo P-C, Hwang J-S, Shu G-J, Chang S-M, Wu H-L, Wu C-I, Chen K-H, Chen L-C.
2022.
Selective CO2-to-CO photoreduction over an orthophosphate semiconductor via the direct Z-scheme heterojunction of Ag3PO4 quantum dots decorated on SnS2 nanosheets, 2022. Sustainable Energy & Fuels. 6(19):4418-4428.: The Royal Society of Chemistry
AbstractDirect Z-scheme heterojunctions are widely used for photocatalytic water splitting and CO2 reduction due to facilitating well-separated photogenerated charge carriers and spatial isolation of redox reactions. Here, using a facile two-step hydrothermal and ion-exchange method, we uniformly decorate silver orthophosphate (i.e., Ag3PO4) quantum dots with an average characteristic size of ∼10 nm over tin(iv) sulphide (i.e., SnS2) nanosheets to form a 0D/2D heterojunction. The direct Z-scheme mechanism, i.e. charge transport for efficient electron (from SnS2) and hole (from Ag3PO4) recombination, is confirmed by the following experiments: (i) ultraviolet and X-ray photoelectron spectroscopies; (ii) photodeposition of Pt and PbO2 nanoparticles on reduction and oxidation sites, respectively; (iii) in situ X-ray photoelectron spectroscopy; and (iv) electron paramagnetic resonance spectroscopy. Owing to the photoreduction properties of Ag3PO4 with orthophosphate vacancies, Z-scheme charge carrier transfer, and efficient exciton dissociation, an optimized heterojunction shows a high CO2-to-CO reduction yield of 18.3 μmol g−1 h−1 with an illustrious selectivity of ∼95% under light illumination, which is about 3.0 and 47.8 times larger than that of Ag3PO4 and SnS2, respectively. The carbon source for the CO product is verified using a 13CO2 isotopic experiment. Moreover, by tracing the peak at ∼1190 cm−1 in the dark and under light irradiation, in situ diffuse reflectance infrared Fourier transform spectroscopy demonstrates that the CO2 reduction pathway goes through the COOH* intermediate.
Quadir, S, Qorbani M, Sabbah A, Wu T-S, kumar Anbalagan A, Chen W-T, Valiyaveettil SM, Thong H-T, Wang C-W, Cheng-YingChen, Lee C-H, Chen K-H, Chen L-C.
2022.
Short- and Long-Range Cation Disorder in (AgxCu1–x)2ZnSnSe4 Kesterites, 2022. Chemistry of Materials. : American Chemical Society
Abstract
Fathabadi, M, Qorbani M, Sabbah A, Quadir S, Huang C-Y, Chen KH, Chen L-C, Naseri N.
2022.
Ultrathin amorphous defective co-doped hematite passivation layer derived via in-situ electrochemical method for durable photoelectrochemical water oxidation, 2022. Journal of Materials Chemistry A. :-.: The Royal Society of Chemistry
AbstractAlthough hematite (i.e., α-Fe2O3) has been widely investigated in photoelectrochemical water oxidation studies due to its high theoretical photocurrent density, it still suffers from serious surface charge recombination and low photoelectrochemical stability. Here we report an in-situ electrochemical method to form a uniform and ultrathin (i.e., 3–5 nm) passivation layer all over the porosities of the optimized ~3.2% Ti-doped α-Fe2O3 photoanode. We unveil the amorphous and defective nature of the in-situ derived layer assigning to a high concentration of oxygen vacancy and intercalated potassium atoms there, i.e., the formation of Ti/K co-doped defective α-Fe2O3-x. Owing to the efficient passivation of surface states, alleviated surface-potential fluctuations, and low charge-transfer resistance at the interface, photoanodes show an average of ~60% enhancement in the photoelectrochemical performance, applied bias absorbed photon-to-current efficiency of 0.43%, and Faradaic efficiency of ~88%. Moreover, the passivation layer prevents direct contact between the electrode material and electrolyte, resulting in less degradation and outstanding photoelectrochemical stability with photocurrent retention of ~95% after ~100 hours, albeit by performing several successive in-situ electrochemical passivation processes. This work presents an industrially scalable method to controllably engineer the interfaces of semiconductors–electrolytes with precious metal-free defective hematite-based co-catalysts for sustainable photoelectrochemical solar-to-fuel conversion applications.
Shelke, AR, Wang H-T, Chiou J-W, Shown I, Sabbah A, Chen K-H, Teng S-A, Lin I-A, Lee C-C, Hsueh H-C, Liang Y-H, Du C-H, Yadav PL, Ray SC, Hsieh S-H, Pao C-W, Tsai H-M, Chen C-H, Chen K-H, Chen L-C, Pong W-F.
2022.
Bandgap Shrinkage and Charge Transfer in 2D Layered SnS2 Doped with V for Photocatalytic Efficiency Improvement. Small. n/a:2105076., Number n/a
AbstractAbstract Effects of electronic and atomic structures of V-doped 2D layered SnS2 are studied using X-ray spectroscopy for the development of photocatalytic/photovoltaic applications. Extended X-ray absorption fine structure measurements at V K-edge reveal the presence of VO and VS bonds which form the intercalation of tetrahedral OVS sites in the van der Waals (vdW) gap of SnS2 layers. X-ray absorption near-edge structure (XANES) reveals not only valence state of V dopant in SnS2 is ≈4+ but also the charge transfer (CT) from V to ligands, supported by V Lα,β resonant inelastic X-ray scattering. These results suggest V doping produces extra interlayer covalent interactions and additional conducting channels, which increase the electronic conductivity and CT. This gives rapid transport of photo-excited electrons and effective carrier separation in layered SnS2. Additionally, valence-band photoemission spectra and S K-edge XANES indicate that the density of states near/at valence-band maximum is shifted to lower binding energy in V-doped SnS2 compare to pristine SnS2 and exhibits band gap shrinkage. These findings support first-principles density functional theory calculations of the interstitially tetrahedral OVS site intercalated in the vdW gap, highlighting the CT from V to ligands in V-doped SnS2.
Daichakomphu, N, Abbas S, Chou T-L, Chen L-C, Chen K-H, Sakulkalavek A, Sakdanuphab R.
2022.
Understanding the effect of sputtering pressures on the thermoelectric properties of GeTe films. Journal of Alloys and Compounds. 893:162342.
AbstractIn this work, we study the effect of sputtering pressures on the thermoelectric properties of GeTe films. The working pressures were differentiated from 3 to 30 mTorr, and the as-deposited films were annealed at 623 K for 10 min in Ar atmosphere. The results show that the working pressure has a significant effect on the Ge content and crystalline size. The turning trend of the Seebeck coefficient with different sputtering pressures corresponds to the Ge content. The surface morphology of annealed film will change from cracks to voids with increasing sputtering pressure. This behavior can be explained by the growth mechanisms model. The voids and relatively low crystalline size of GeTe films affect to the reduction of the electrical conductivity. In addition, the void content decreased as film thickness was increased. Therefore, controlling the working pressures in the sputtering process and film thickness is important for the thermoelectric performance of GeTe thin film. In our work, we prove that the thermoelectric properties of GeTe films could be optimized effectively by simply tuning different sputtering conditions.