Fig. 4. Characterization of electronic properties and surface H₂ and H₂-CO₂ chemistry of the samples S1 and S4.

a Photocurrent saturation and decay plot acquired at ~200 °C with a 1:1 ratio of CO₂/H₂ and under a 100 W LED white lamp. b Corresponding in situ I−V plot. In situ DRIFTS spectra of S4 obtained c under H₂ at room temperature and d under both H₂ and CO₂ (1:1) with increased temperatures. The collected DRIFTS spectra are subtracted by the background signal of S4 obtained under He.