Single Au Anion Can Catalyze Acetylene Hydrochlorination: Tunable Catalytic Performance from Rational Doping

In this work, for the first time it is demonstrated that supported single Au in either a positive or a negative charge state can catalyze acetylene hydrochlorination competitively with regard to other reported Au catalysts by using first-principle calculations. The nitrogen and boron dopants on the single-walled carbon nanotube (SWCNT) not only behave as stable anchoring positions for the single Au but also effectively adjust the electronic structure of Au. It is revealed that Au becomes positively and negatively charged on nitrogen- and boron-doped SWCNT, respectively. The different charge state of Au directly influences the interactions with the reactants C2H2. Moreover, the charge transfer during C2H2 adsorption exhibits an opposite effect for Au cation and anion. Therefore, the dopant on the support is effectively a tool to tune the properties of the supported single Au. The reaction obeys an Eley–Rideal-like mechanism, in which C2H2 binds first, followed by HCl activation and product formation. Detailed reaction pathway analysis reveals that both positively and negatively charged Au are active acetylene hydrochlorination catalysts with comparable reaction barriers. The current work not only broadens the scope of Au catalysts in acetylene hydrochlorination, with the inclusion of negative Au, but also verifies the effectiveness of support doping to tune the catalytic performance.