Figure 4

(a) A representative time-lapse microscopy image of CO₂ bubbles near the junction and the outlet in the presence of Ni NPs at different salinities (0%, 2%, 4%, 6%, 8%, 10%, 15%, and 30% NaCl). (b) Histograms of sizes of CO₂ bubbles near the junction (the initial location) and the outlet (the final location) to confirm the effect of salinity on Ni NPs’ catalytic potential. (c) The percent changes in average diameter of CO₂ bubbles near the outlet in the presence and absence of Ni NPs at different salinities (**p <0.01). (d) The graphs of experimentally measured ζ potential and conductivity of Ni NPs solution at different salinities. (Error bars show mean ± standard error of the mean from three independent measurements). (e) The electrostatic double layer potential (ϕ_elec) between two Ni NPs from the extended-DLVO theory at various ionic strengths.