From Serendipity to Exploration: Synthesis and Properties of PtSiSb

PtSiSb is a compound with covalent Si-Sb bonds, which are relatively rare instances in solid-state materials. The original report on PtSiSb indicates synthetic challenges for the isolation of single-phase samples, as well as potential discrepancies in the predicted electronic structure and experimental transport properties. We considered PtSiSb as a case study with the objective of demonstrating the importance of synthesis as a bridge between theoretical predictions and experimental properties. Using guidance from in situ powder X-ray diffraction, the synthesis of single-phase polycrystalline samples was developed, allowing further experimental characterization of transport and catalytic properties. Thermal conductivity and heat capacity demonstrated anomalous behavior, indicating an unconventional phonon scattering mechanism in PtSiSb. Charge transport measurements indicated semimetallic behavior. Hydrogen evolution reaction (HER) tests in acidic electrolyte revealed that the PtSiSb cathode needs an overpotential η₁₀ = 120 mV to achieve a current density j = -10 mA/cm². This is lower activity than elemental Pt but comparable to known and active transition-metal phosphide HER catalysts, such as CoP, with η₁₀ = 93 mV when measured at identical conditions.