Fig. 2: Characterisation of the photocatalysts.

a XRD spectra of TiO2, Pd/TiO2, Cu/TiO2 and PdCu/TiO2. b Raman spectra of TiO2, Pd/TiO2, Cu/TiO2 and PdCu/TiO2. c UV-Vis absorption spectra of TiO2, Pd/TiO2, Cu/TiO2 and PdCu/TiO2. d HR-TEM image of PdCu/TiO2. e HAADF-STEM image and EDX elements mapping of PdCu/TiO2. f XPS spectra of Pd1/TiO2 and Pd1Cu1/TiO2 (Pd 3d) before reaction. g Cu K-edge XANES spectra of PdCu/TiO2 and PdCu/TiO2 after reaction in reference to Cu foil, Cu2O and CuO. Source data are provided as a Source Data file.