Samples	Control sample band gap (eV)	Decreasing in band gap (eV)	References
GO-doped ZnO	3.6	2.9	[61]
Ag-doped GO	4.10	3.50	[2]
GO-doped ZnO	3.10	2.98	[62]
GO-doped MgO	5.0	4.8	Present study