Performance comparison of NO₂⁻ oxidation of the as-synthesised ZnO (our work) with other reported electrocatalytic systems from the literature.

Sr. no.	Electrode	Detection limit (μM)	Ref.
1	f-ZnO@r-FGO	33	71
2	Gr-Nafion/GCE	11.61	72
3	Au-NPs/ethylenediamine/GCE	45	73
4	Nafion/SLGnP-TPA-Mb/GCE	10	74
5	Nano-Au/P3MT/GCE	2.3	75
6	ZnO/GCE	1	Present work