Previous research on the ternary Ti-Fe-Sb system has revealed that stoichiometric TiFeSb cannot exist as a stable compound, whereas a single-phase TiFe_1.33Sb alloy with the half-Heusler-like structure has been synthesized by adding excessive Fe. In this work, we report that TiFeSb can also be stabilized by filling additional Cu to the vacant 4d site of the half-Heusler lattice. Our experiments indicate that the TiFeCu_xSb (x = 0–0.25) samples exhibit a p-type conduction with extremely high carrier concentration ((0.5 –2.5) × 10²² cm⁻³)), while these samples attain very large Seebeck coefficients, over 100 μV/K in the whole measured temperature range for the samples with x = 0.15–0.25. In addition, a logarithmic divergence of the temperature-dependent specific heat capacity (C_P/T) is observed at low temperatures, implying the strange-metal behavior of TiFeCu_xSb samples. The partial filling of the vacant 4d site results in significantly reduced lattice thermal conductivity, leading to the low total thermal conductivity of 2.8 W·m⁻¹·K⁻¹ at 823 K for the TiFeCu_0.20Sb sample. Consequently, a dimensionless figure of merit zT of 0.54 at 923 K is realized for TiFeCu_0.20Sb, demonstrating that promising thermoelectric materials with intriguing physical properties can be discovered in the composition gap of half- and full-Heusler alloys.

Cluster catalysts are rapidly growing into an important sub-field in heterogeneous catalysis, owing to their distinct geometric structure, neighboring metal sites, and unique electronic structure. Although the thermodynamics and kinetics of the formation of nanoparticles have been largely investigated, the precise synthesis of clusters in wet chemical methods still faces great challenges. In the study, a quenching strategy of asymmetric temperature in solution for the rapid generation of vacancy-defect rich clusters is reported. The quenching process can be used to synthesize multitudinous metal compound clusters, including metal oxides, fluorides, oxygen-sulfur compounds, and tungstate. For oxygen evolution reaction (OER), IrO₂ clusters with abundant oxygen vacancies were obtained and uniformly dispersed in the solution. Compared to commercial IrO₂, the prepared IrO₂ cluster can be directly loaded on carbon paper and used as binder-free electrodes, which exhibit higher OER activity and long-term operational stability in alkaline electrolytes. The quenching strategy provides a simple and efficient method for the synthesis of clusters, which has tremendous potential for industrial-scale preparation and application, especially can be further applied to flow electrochemical generators.