Fig. 1: Characterization of HKUST-1.

a The SEM image of HKUST-1 single crystal after activation. b The PXRD of HKUST-1 crystals after activation. c A cross-section TEM image of Au/HKUST-1 heterointerfaces prepared by FIB-SEM. d The Raman spectra of Au-coated HKUST-1 crystals after activation and immersed in water for 20, 40, and 70 min.