Table 1.

Comparison of electrocatalytic activity with previous reported catalysts

Catalysts	OPa (V)	η b (V) (at 10 mA cm−2)	TSc (mV dec−1)	Electrolyte	References
Porous Co3O4 nanoplates	1.514	0.523	71	0.1 M KOH	[40]
Co3O4/mildly oxidized MCNT	1.51	0.39	65	0.1 M KOH	[41]
CoO/N-doped crumpled graphene	N. A.	0.34	71	0.1 M KOH	[42]
Au-meso-Co3O4	1.53	0.44	46	0.1 M KOH	[43]
Hollow Ni–Co oxide nanosponges	1.50	0.36	61	0.1 M KOH	[44]
Rutile RuO2	>1.70	141	N. A.	0.1 M KOH	[45]
IrO2/C	N. A.	0.37	N. A.	0.1 M KOH	[21]
This work	1.41	0.30	84	0.1 M KOH	–

^a OP = onset potential; ^b η = over-potential at current density of 10 mA cm⁻²; ^c TS = Tafel slope