Summary of the calculated unit cell lattice parameters (a, b, c and β) of the different CuO nanoparticles compared to reference tenorite CuO of monoclinic crystal structure with C2/c symmetry.

Sample	a (nm)	b (nm)	c (nm)	β (deg)	Strain (s)
CuO(A2 h–C2 h)	0.486	0.351	0.508	99.42	0.038
CuO(A24 h–C2 h)	0.483	0.340	0.521	99.18	0.032
CuO(A24 h–C4 h)	0.468	0.341	0.509	99.39	0.00
CuO(A72 h–C2 h)	0.478	0.328	0.506	99.54	0.021