Fig. 3. Activity and selectivity for CH₄ over Sr₂CuWO₆.

a DFT-calculated energy diagrams for CH₄ and C₂H₄ formation on Sr₂CuWO₆(001) surface starting with *CO (TS: transition state). b FEs for various gas products over Sr₂CuWO₆ at different applied current densities. c ${\text{FE}}_{\text{C}{\text{H}}_4}$ of Sr₂CuWO₆ and CuO/WO₃ at different applied current densities. d ${\text{FE}}_{\text{C}{\text{H}}_4}/{\text{FE}}_{{\text{C}}_2{\text{H}}_4}$ or $j_{\text{C}{\text{H}}_4}/j_{{\text{C}}_2{\text{H}}_4}$ of Sr₂CuWO₆ and CuO/WO₃ at different applied current densities. e ${\text{FE}}_{\text{C}{\text{H}}_4}$ and $j_{\text{C}{\text{H}}_4}$ of Sr₂CuWO₆, in comparison with those of Cu-based perovskite oxides reported in the literature (Supplementary Table 4). The error bars represent the mean ± standard deviation (SD, n = 3 replicates).