ln ( C
) versus time. Plots of ln (C
/C0) versus time for the catalytic reduction of 4-NP with NaBH4(a) by Ag/rGO nanocomposite at different temperatures; (b) by different amounts of Ag/rGO nanocomposite; (c) by Ag/rGO nanocomposites 1C, 3C, and 5C; and (d) by Ag/rGO nanocomposite at different initial 4-NP concentrations. C0 and C
denote the concentrations of 4-NP when times were 0 and t, respectively. [NaBH4]/[4-NP] = 100. Unless otherwise specified in the figures, [4-NP] = 0.05 mM, catalyst amount = 0.25 mg/100 mL, temperature = 25°C, and Ag/rGO nanocomposite = 3C. The inset in (a) indicates the corresponding Arrhenius plot. The inset in (b) indicates the relationship between the pseudo-first-order rate constant and catalyst amount.