Chien-Neng Liao

The inefficient carrier transport of earth-abundant tin sulfide (SnS), arising from its intrinsically low crystal symmetry, limits its thermoelectric performance at low temperatures. Here, the substitutional Ag ⁺ doping modified the Na-doped SnS crystal structure by reinforcing lattice dynamical anisotropy and enhancing in-plane transport properties. Concurrently, the reconstructed valence-band structure evolved into a modulated multiband configuration, increasing the density-of-states effective mass while preserving high carrier mobility. The resulting highly metallic conductivity combined with high thermopower yields an ultrahigh room-temperature power factor of ~ 101 µW cm ^-1 K ^-2 in Sn _0.96 Na _0.01 Ag _0.03 S single crystals. Coupled with the intrinsically low thermal conductivity of SnS, the optimized crystal achieved the figure of merit ( zT ) of ~ 1.06 at 300 K and ~ 2.0 at 573 K, delivering a conversion efficiency of ~ 3.3% and an output power density of ~ 0.31 W cm ^-2 in a single-leg module under a 243 K temperature gradient. These results demonstrate the effectiveness of multiband engineering in SnS and establish it as a highly promising low-cost thermoelectric material for near-room-temperature energy conversion.

Copper nanowires with fivefold twinned structures (t-CuNWs) are shown to be effective as cathode catalysts for the electrochemical reduction of CO₂ (CO₂RR) in a zero-gap electrolyzer to produce ethylene.

Cuprous oxide (Cu₂O) is a promising material for photoelectrochemical water splitting due to its favorable band structure, environmental acceptability, nontoxicity, and ease of fabrication. In this study, (111)-textured Cu₂O films decorated with numerous ZnO nanoparticles (NPs), namely ZCO films, are synthesized by a facile one-step electrodeposition method. The mechanism for forming ZnO NPs during the electrodeposition of Cu₂O films is proposed. Based on the Mott-Schottky analysis and electrochemical impedance spectroscopy measurements, the presence of ZnO NPs on the Cu₂O films enhances band bending and reduces charge transfer resistance to the electrolyte, which is advantageous for separating photoexcited electron and hole carriers in the illuminated ZCO films. Additionally, excess oxygen vacancy defects may facilitate the interdefect hopping of photoelectrons by minimizing the recombination probability of transporting photocarriers within the ZCO films according to photoluminescence spectroscopy analysis. The ZCO film exhibits a 40% increase in photocurrent density over the pristine Cu₂O film in 1 M Na₂SO₄ solution under AM1.5G illumination. This study provides a facile synthesis route for creating high-performance Cu₂O-based photocathodes through heterojunction and crystal defect engineering.

This study investigates copper nanowires with fivefold twinned structures (t-CuNWs) as catalysts for the electrochemical reduction of CO2 (CO2RR) in a zero-gap flow cell with 1 M KOH as anolyte. The t-CuNWs, with surfaces enclosed by (100) facets, were selected for their enhanced CO adsorption strength, which promotes C–C coupling—a key pathway toward multi-carbon (C2+) products. Additionally, the entangled t-CuNWs exhibits enhanced hydrophobicity when compared to commercial Cu nanoparticles (CuNPs), which can reduce flooding issues and contribute to high stability during electrochemical operation. These characteristics distinguish t-CuNWs from CuNPs in terms of activity and stability. The t-CuNWs exhibited ~ 40% C2H4 faradic efficiency (FE) for more than 4 hours under a current density of 100 mA/cm2, while commercial CuNPs exhibited ~ 20% C2H4 FE for less than 4 hours under the same condition. These findings highlight the potential of (100) faceted t-CuNWs for efficient and durable C2+ product formation in CO2RR with facet engineering and hydrophobicity control.

Ultrahigh-density coherent twin boundaries are introduced in copper nanowires through the process of template-assisted electrodeposition.