Fig. 2: Characterization of the heterogeneous catalyst.

a Typical transmission electron microscopy (TEM) of Rh2O3 nanoparticles on GaN and size distribution. b X-ray diffraction (XRD) patterns of pristine Rh2O3/GaN (red), commercial GaN (black), and spent Rh2O3/GaN (gray). c X-ray photoelectron spectroscopy (XPS) spectra of pristine (red) and spent (gray) Rh2O3/GaN in the Ga 3d and Rh 3d regions. d Recycling experiments of the heterogeneous catalyst.