Hot-pressing synthesis and first-principles investigation of Au-bearing arsenopyrite

Arsenopyrite, a significant natural Au-host mineral, is often intergrown with sulfide minerals, complicating its isolation. Synthesizing high-purity, dense Au-bearing arsenopyrite is essential for studying its properties. This study employed hot-press sintering (with optimal conditions identified at 450°C and 1.0 GPa) using purified arsenopyrite and Au powders to fabricate conductive, dense Au-bearing arsenopyrite. The sintered product exhibited high purity and increased density (6.259 ± 0.021 g/cm 3 vs. the original 5.923 ± 0.037 g/cm3). Electrochemical testing (via open-circuit potential and cyclic voltammetry) demonstrated favorable performance of the synthesized material. Density functional theory (DFT) calculations confirmed phase stability under 0–10 GPa, revealing that Au preferentially substitutes for Fe in arsenopyrite, introducing gap states that convert it from a semiconductor (indirect bandgap: 0.7075 eV) to a conductor. Bader charge analysis indicated Au carries a negative charge (-0.056 e), while As exhibits positive charges. Fe was identified as the most reactive site. These results provide a high-purity material platform for studying Au-bearing arsenopyrite and a theoretical basis for elucidating its properties.