Table 3.

Comparison of the catalytic activity of Pd-ZnO-Scb with those of other catalysts in 4-NP reduction.

Entry	Catalyst	Time	Ref
1	Au/PMMA	600 s	62
2	CuBDC•DMF	5 min	63
3	FPP/Au microspheres	13 min	64
4	AgNPs/ESM	900 s	65
5	AgNPs@MWCNTs-polymer composite	5 min	66
6	Ni-RGO	480 s	67
7	Pt/Fe2O3 MF	12 min	68
8	AgNPs@NC	8 min	69
9	Au@PZS@CNTs	16 min	70
10	RS–AgCl@Ag	4 min	71
11	Pd–ZnO–Scb	135 s	Present study