title: Sub-surface alloying largely influences graphene nucleation and growth over transition metal substrates.
abstract: Sub-surface alloying (SSA) can be an effective approach to tuning surface functionalities. Focusing on Rh(111) as a typical substrate for graphene nucleation, we show strong modulation by SSA atoms of both the energetics and kinetics of graphene nucleation simulated by first-principles calculations. Counter-intuitively, when the sub-surface atoms are replaced by more active solute metal elements to the left of Rh in the periodic table, such as the early transition metals (TMs), Ru and Tc, the binding between a C atom and the substrate is weakened and two C atoms favor dimerization. Alternatively, when the alloying elements are the late TMs to the right of Rh, such as the relatively inert Pd and Ag, the repulsion between the two C atoms is enhanced. Such distinct results can be well addressed by the delicately modulated activities of the surface host atoms in the framework of the d-band theory. More specifically, we establish a very simple selection rule for optimizing the metal substrate for high quality graphene growth: the introduction of an early (late) solute TM in the SSA lowers (raises) the d-band center and the activity of the top-most host metal atoms, weakening (strengthening) the C-substrate binding, meanwhile both energetically and kinetically facilitating (hindering) the graphene nucleation, and simultaneously promoting (suppressing) the orientation disordering the graphene domains. Importantly, our preliminary theoretical results also show that such a simple rule is also proposed to be operative for graphene growth on the widely invoked Cu(111) catalytic substrate.
authors.affiliation: International Laboratory for Quantum Functional Materials of Henan, School of Physics and Engineering, Zhengzhou University, Zhengzhou, 450001, China. z.x.guo@ucl.ac.uk sflizzu@zzu.edu.cn.
authors.forename: Liying
authors.initials: L
authors.lastname: Zhang
authors.affiliation: International Laboratory for Quantum Functional Materials of Henan, School of Physics and Engineering, Zhengzhou University, Zhengzhou, 450001, China. z.x.guo@ucl.ac.uk sflizzu@zzu.edu.cn.
authors.forename: Xingju
authors.initials: X
authors.lastname: Zhao
authors.affiliation: International Laboratory for Quantum Functional Materials of Henan, School of Physics and Engineering, Zhengzhou University, Zhengzhou, 450001, China. z.x.guo@ucl.ac.uk sflizzu@zzu.edu.cn.
authors.forename: Xinlian
authors.initials: X
authors.lastname: Xue
authors.affiliation: International Laboratory for Quantum Functional Materials of Henan, School of Physics and Engineering, Zhengzhou University, Zhengzhou, 450001, China. z.x.guo@ucl.ac.uk sflizzu@zzu.edu.cn.
authors.forename: Jinlei
authors.initials: J
authors.lastname: Shi
authors.affiliation: International Laboratory for Quantum Functional Materials of Henan, School of Physics and Engineering, Zhengzhou University, Zhengzhou, 450001, China. z.x.guo@ucl.ac.uk sflizzu@zzu.edu.cn.
authors.forename: Chong
authors.initials: C
authors.lastname: Li
authors.affiliation: International Laboratory for Quantum Functional Materials of Henan, School of Physics and Engineering, Zhengzhou University, Zhengzhou, 450001, China. z.x.guo@ucl.ac.uk sflizzu@zzu.edu.cn.
authors.forename: Xiaoyan
authors.initials: X
authors.lastname: Ren
authors.affiliation: International Laboratory for Quantum Functional Materials of Henan, School of Physics and Engineering, Zhengzhou University, Zhengzhou, 450001, China. z.x.guo@ucl.ac.uk sflizzu@zzu.edu.cn.
authors.forename: Chunyao
authors.initials: C
authors.lastname: Niu
authors.affiliation: International Laboratory for Quantum Functional Materials of Henan, School of Physics and Engineering, Zhengzhou University, Zhengzhou, 450001, China. z.x.guo@ucl.ac.uk sflizzu@zzu.edu.cn.
authors.forename: Yu
authors.initials: Y
authors.lastname: Jia
authors.affiliation: International Laboratory for Quantum Functional Materials of Henan, School of Physics and Engineering, Zhengzhou University, Zhengzhou, 450001, China. z.x.guo@ucl.ac.uk sflizzu@zzu.edu.cn and Department of Chemistry, University College London, London WC1H 0AJ, UK.
authors.forename: Zhengxiao
authors.initials: Z
authors.lastname: Guo
authors.affiliation: International Laboratory for Quantum Functional Materials of Henan, School of Physics and Engineering, Zhengzhou University, Zhengzhou, 450001, China. z.x.guo@ucl.ac.uk sflizzu@zzu.edu.cn.
authors.forename: Shunfang
authors.initials: S
authors.lastname: Li