Gold single-atom catalysts (SACs) exhibit outstanding reactivity in acetylene hydrochlorination to vinyl chloride, but their practical applicability is compromised by current synthesis protocols, using aqua regia as chlorine-based dispersing agent, and their high susceptibility to sintering on non-functionalized carbon supports at >500 K and/or under reaction conditions. Herein, a sustainable synthesis route to carbon-supported gold nanostructures in bimetallic catalysts is developed by employing salts as alternative chlorine source, allowing for tailored gold dispersion, ultimately reaching atomic level when using H2 PtCl6 . To rationalize these observations, several synthesis parameters (i.e., pH, Cl-content) as well as the choice of metal chlorides are evaluated, hinting at the key role of platinum in promoting a chlorine-mediated dispersion mechanism. This can be further extrapolated to redisperse large gold agglomerates (>70 nm) on carbon carriers into isolated atoms, which has important implications for catalyst regeneration. Another key role of platinum single atoms is to inhibit the sintering of their spatially isolated gold-based analogs up to 800 K and during acetylene hydrochlorination, without compromising the intrinsic activity of Au(I)-Cl active sites. Accordingly, exploiting cooperativity effects of a second metal is a promising strategy towards practical applicability of gold SACs, opening up exciting opportunities for multifunctional single-atom catalysis.
Keywords: acetylene hydrochlorination; bimetallic catalysts; gold; platinum; single-atom catalysis.
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