Table 6.

Catalytic systems, major products, maximum FEs, and mechanisms of Co complexes in electrochemical CO₂ reduction (n.a.=not available, prop.=proposal, comp.=computational investigation, exp.=experimental evidence).

Entry	Cat. system	Substitution	Major product	Max. FE (%)	Mechanism	Basis	Method	Ref.
1a		n=1, 2 R= –, H, Me X= –, MeCN, NCS, Cl, Br	CO/H2O H2	45±7 [235] 30±8 [235]	ETM	exp.[236 comp. [237]	IL, IR DFT	[ 235 , 236 , 237 , 238 ]
1b		–	CO/H2O	82	ETM	comp.	DFT	[59]
1c		–	HCO2H	80	ETM (CO) ETH (HCO2H)	exp. comp.	IR‐SEC DFT	[239]
1d		–	HCO2H	60	n.a.	n.a.	n.a.	[240]
2a		R=H, Me	CO/H2O H2	93 (CO+H2)	ETH	prop.	n.a.	[241]
3a		Ar=Ph, C6H4CF3, C6H4NH2, C6H4NMe3 +, C6H3(OH)2, C6H4OMe, C6H3(OMe)2, C6H4Cl, C6H4Br, C6H4F, C6F5 n=0, 1 X= –, Cl	CO/H2O	97 [242]	ETM	prop. [242]	n.a.	[ 242 , 243 ]
3b		–	CO/H2O	89	ETM	prop.	n.a.	[244]
3c		R1=H, tBu, OC8H17, O‐py R2=H, tBu, OC8H17, O‐py R3=H, NMe3 +	CO/H2O H2 MeOH	100 [120] 72 [120] 20 [231]	ETM	exp. [230] comp. [245]	PSCAS DFT	[120, 230, 231, 243e, 245, 246]
3d		–	CO	97	n.a.	n.a.	n.a.	[247]
4		L=PPh3 R=S‐(PEG7)‐OCH3	HCO2 − CH3OH H2CO CH3CH2OH CH3CO2 − H2	12 59 10 48 13 36	ETM	exp.	EPR, GC‐MS, IL, IR‐SEC, NMR	[234]
5a		–	CO/H2O	77	n.a.	n.a.	n.a.	[248]
5b		R=CH3 R∩R=CH2, (CH2)2	CO/H2O	98	ETM	comp.	DFT	[249]
5c		n=0, 1 X= –, Cl	CO/H2O	16	ETM	exp. comp.	IR, UV/Vis DFT	[250]
6		R=H, Me, allyl	CO/H2O	98	ETM	comp.	DFT	[ 226 , 251 ]
7		L=py, qui (+ dimer)	CO/H2O	84	ETM	comp.	DFT	[252]
8		R1=H, tBu, OMe, p‐Me‐C6H4, p‐Cl‐C6H4 R2=H, tBu	CO/H2O H2	37 [253] 23 [253]	ETM	prop. [253]	n.a.	[ 253 , 254 ]
9	[Co(PPh3)2L]n+	L=4,4′‐di‐Me‐bpy, 4‐Me‐1,10‐phen, 2‐Me‐8‐hydroxyqui n=1, 2	CO/CO3 2− HCO2 −	83 44	ETM	prop.	n.a.	[255]
10a	[CoCp(L)I]+	R1=Cy, Ph R2=Ph, Bn	HCO2 − H2	99±8 67±5	ETH	comp.	DFT	[256]
10b		n=1, 2 R=H, Me X=MeCN, I	CO/H2O	70	ETM	prop.	n.a.	[257]
11a		–	CO/H2O	94 [184]	ETM	prop. [184]	n.a.	[184, 229, 258]
11b		Y=CH2, (CH2)2, (CH2)3	CO/H2O HCO2H	104±6 [259] 23 [260]	ETM	prop.	n.a.	[259]
12		–	CO/H2O	96	ETM	comp.	DFT	[261]
13a		–	CO/H2O	95±2	ETM	comp.	DFT	[262]
13b		L∩L=dppe, bpy, 4,4'‐(OMe)2bpy, 2‐pyridinethiolato n=0, 1	CO/H2O HCO2H H2	92±4 [263] (CO+H2) 64 [264] 19 [264]	ETM (CO) ETH (HCO2H/H2)	comp.	DFT	[ 263 , 264 ]
14		–	n.a.	n.a.	ETM	exp. comp.	XRD coupled cluster	[228]
15	[Co(L)2]2+		CO/H2O H2	23 42	ETM (CO) ETH (H2)	prop.	n.a.	[265]
16		R=MeCp	C2O4 2−	80	n.a.	n.a.	n.a.	[266]