Previously reported tri-metal LDHs using urea hydrolysis and co-precipitation where a range of metal ratios was investigated (subs. M, M = substituted metal).

LDH	Subs. M	Variations	Method	Characterization methods	Ref.
(Mg/Al + Fe)–CO3	Fe	Mg : (Al + Fe) = 2 : 1	Co-precipitation	PXRD, FTIR, TGA, DTA, UV-Vis, BET, TEM, XPS	31
MgAlFe, MnMgAlFe	Fe, Mn	0% wt, 1% wt, 5% wt and 10% wt	Co-precipitation	XRD, FTIR, TGA, DSC, catalytic test	32
MgCuFe	Cu	2 : 1 : 1, 2 : 0.5 : 1 and 2 : 0 : 1	Co-precipitation	XRD, catalytic tests	34
CuMgAl	Cu	5 mol% Cu, temperature variations (600 °C, 700 °C and 800 °C)	Co-precipitation	XRD, FTIR, EPMA, TGA-DTG-QMS, BET, catalytic tests, DRUV-Vis	35
MgZnAl	Zn	2 : 0 : 1, 1.7 : 0.3 : 1.0, 1.5 : 0.5 : 1.0, 1.3 : 0.7 : 1.0, 1.0 : 1.0 : 1.0	Homogeneous Co-precipitation	XRD, FTIR, TEM, SEM, TG-DTA	36
MgAl, CuMgAl, FeMgAl	Cu, Fe	71 : 29, 5 : 66 : 29, 5 : 66 : 29 (atomic ratios)	Co-precipitation	XRD, UV-vis-DRS, TG-DTA-QMS, STEM, BET, redox properties	37
CuMgAl	Cu	0 : 4 : 2, 1 : 3 : 2, 2 : 2 : 2, 3 : 1 : 2, and 4 : 0 : 2	Co-precipitation	XRD, TG, DTA, BET, TPD, catalytic activity	38
MMgAl–CO3–NO3	Cu, Co, Ni	M : Mg (0.10 : 0.61) and M : Al (0.10 : 0.29)	Co-precipitation	High temperature XRD, TGA-DTA-MS, TPR	42
ZnAl, ZnCuAl, ZnCoAl	Cu, Co	2 : 1, 1.9 : 0.1 : 1, 1.75 : 0.25 : 1, 1.5 : 0.5 : 1, 1 : 1 : 1	Co-precipitation	XRD, FTIR, Raman spectroscopy, UV-Vis, TEM, photocatalytic activity	40
MgCoAl, MgNiAl, MgCuAl	Co, Cu, Ni	M(ii) : Mg(ii) : Al(iii) 1 : 6 : 2	Co-precipitation	XRD, XRF, TG MSD, FTIR and Raman spectroscopy	46
MgAl, MgCoAl, MgNiAl, MgFeAl	Fe, co, Ni	MgCl2·6H2O = 0.29AlCl3·6H2O = 0.1, CoCl2 = 0.01, FeCl2·4H2O = 0.01, NiCl2·6H2O = 0.01	Co-precipitation	PXRD, EXAFS, XANES, FTIR, SEM-EDX, TGA	47
MgCoAl, NiCoAl	Mg, Ni	Molar ratios M2+ : M3+ of 2 (x = 1 : 3)	Urea hydrolysis	XRD, NMR, TGA-DTA, FTIR, SEM and N2 adsorption–desorption	43
ZnMgAl	Zn	(Zn + Mg) : Al = 2 : 1, Zn/Mg = 0, 0.125, 0.5 and 0.8	Modified urea hydrolysis with co-precipitation	XRD, SEM, FTIR, UV-Vis, AAS	42
MgZnAl	Mg, Zn	((Mg + Zn)/Al molar ratio = 5.67), MgZn (25 : 75) Al, MgZn (50 : 50) Al, MgZn (75 : 25) Al	Modified urea hydrolysis with co-precipitation	XRD, FTIR, TGA, DTA, elemental analysis, SEM and TEM	44
FeCoAl, ZnCoAl	Fe, Zn	M/(M + Co) = 0.8, 0.5, 0.2	Urea hydrolysis	XRD, SEM and UV-Vis	41
MgFeAl, MgCuAl, MgZnAl	Fe, Cu, Zn	25 mol%	Hydrothermal	XRD, SEM, BET, particle size, ICP-OES, FTIR, TGA, dynamic heat stability, thermal stability	45