Single Au atom supported defect mediated boron nitride monolayer as an efficient catalyst for acetylene hydrochlorination: A first principles study

Abstract

• Monovacancy defect (nitrogen and boron) in boron nitride effectively adjust the properties of single gold and create the different charge state of Au. • Defective sites are stable active site for Au adsorption compare to pristine one. Single gold anion shows good catalytic performance in reaction which is comparable with single gold cation. • An E-R like reaction mechanism is revealed which begins with C 2 H 2 adsorption followed by HCl activation. • A novel LH mechanism with comparatively lower energy barrier than ER mechanism observed for Au/hBN • Defective boron nitride supported single Au atom catalyst show excellent stability and good catalytic performance towards acetylene hydrochlorination reaction. Hexagonal boron nitride (hBN) with defects shows remarkable performance as catalyst support for single-atom stabilization in several catalytic reactions, such as CO oxidation, N 2 fixation, and ORR. However, the anchoring sites for single-atoms and their catalytic performance towards acetylene hydrochlorination still needs a comprehensive investigation. The boron and nitrogen-vacancy in hBN not only stabilizes Au but can also effectively tune its electronic structure. The single-atom Au has charged negatively and positively on hBN with the formation nitrogen (hBNv) and boron (hBvN) vacancy, respectively. The electronic structure analysis, MD simulations, phonon band structure, and migration barrier uncovered the stability of Au supported on hBN. The reaction proceeded either with Eley–Rideal (E-R) mechanism, starting with C 2 H 2 adsorption after that HCl activation, product formation, or with Langmuir–Hinshelwood (L-H) method, starting with co-adsorption of C 2 H 2 and HCl. The L-H mechanism results in a smaller reaction barrier of 0.90 and 1.15 eV compared to the counterpart E-R mechanism with a barrier of 1.14 and 1.25 eV for Au/hBNv and Au/hBvN respectively. Moreover, both Au in cation and anion state can efficiently catalyze acetylene hydrochlorination with a competing energy barrier. Overall, current research gives a comprehensive explanation of the catalytic properties of hBN-based single-atom Au catalyst. Defected boron nitride can tune the electronic structure of Au and both Au cation and anion shows comparable performance towards acetylene hydrochlorination.