Fig. 3. (A) UV-vis absorption spectra of the catalytic reduction of 4-NP to 4-AP at different reaction times using conditions CAT 1; (B) kinetics and corresponding rate constants the reduction reaction of 4-NP⁻ to 4-AP with different HCP·NHC@AuNP loadings (CAT 1–3); (C) conversion of 4-NP⁻ over 10 consecutive cycles in the flow reactor (flow 0.25 mL min⁻¹); FCAT 1; (D) schematic of the flow reactor setup; (E) high resolution XPS of N 1s and (F) Au 4f scans after 10 flow-through cycles.