Fig. 5. Simulation of defect reactivity in binary mixtures.

(A) Simulation setup of a 50% water-methanol mixture on hBN. Oxygen is shown in red. Hydrogen is shown in white. Carbon is shown in teal. Boron is shown in brown, and nitrogen is shown in dark blue. The gray dashed lines represent the hydrogen bonds between oxygen and hydrogen atoms. (B) Energy barriers for a proton reacting with the negatively charged boron vacancy $V_B^{-}$ in a 50% mixture of methanol and water with one water and one methanol molecule in the first solvation shells of the hydronium ion near the defect as shown in (A). Blue: Defect in the ground state. Red: Defect in the excited state. The desorption energy barrier is shown as ΔE. The inset further shows the difference in the electron density between the excited and the ground state (blue indicates a positive value of charge density difference and yellow indicates a negative charge density difference). (C) Desorption energy barrier ΔE_GS and ΔE_ES for a defect in ground state and excited state, respectively, with different molecules in the first solvation shell of the hydronium ion. (i) Two water molecules; (ii) one water and one methanol molecule; (iii) two methanol molecules.