Supplementary Material R1 (clean, not marked-up)

STM images of Cu(100), 0.1 ML Ni/Cu(100), 0.3 ML Ni/Cu(100) and 0.6 ML Ni/Cu(100); CO2 TPD profiles of Cu(100) at 100 K; O 1s, C 1s and Ni 2p XPS spectra of clean Cu(100), 0.1 ML Ni/Cu(100) and 0.6 ML Ni/Cu(100), Cu 2p XPS spectra of clean Cu(100) and 0.3 ML Ni/Cu(100) surface after exposed to CO2 from UHV to 1 mbar in sequence; TPD profiles of 0.1 ML Ni/Cu(100) and 0.6 ML Ni/Cu(100) after 1 mbar CO2 treatment; XPS and TPD results of 0.3 ML Ni/Cu(100) with varying O2 pre-coverage, reacting with CO2 of 10-2 mbar; Optimized structural model of CO2 adsorbed on Ni/Cu(100).