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Topics in Current Chemistry (2018) 376:42
Table 1
Summary of reaction equations of different types of DUFCs (K
+
is taken as the cation for example)
Direct urea-O
2 (alkaline) fuel cell
Direct urea-H
2 O
2 (alkaline) fuel cell
Direct urea-H
2 O
2 (acidic) fuel cell
Anodic reaction
CO(NH
2 )
2 + 6 KOH ⇄ N
2 +
CO
2 + 5H
2 O + 6K
+
+ 6e
−
E
θ
= − 0.75 V
CO(NH
2 )
2 + 6 KOH ⇄ N
2 +
CO
2 + 5H
2 O + 6K
+
+ 6e
−
E
θ
= − 0.75 V
CO(NH
2 )
2 + 6 KOH ⇄ N
2 + CO
2 + 5H
2 O + 6K
+
+ 6e
−
E
θ
= − 0.75 V
Cathodic reaction 3/2O
2 + 3H
2 O + 6 K
+
+ 6e
−
⇄ 6KOH
E
θ
= 0.40 V
3H
2 O
2 + 6 K
+
+ 6e
−
⇄ 6KOH or
3HO
2
−
+ 9 K
+
+ 3H
2 O + 6e
−
⇄ 9KOH
E
θ
= 0.88 V
3H
2 O
2 + 3H
2 SO
4 + 6e
−
⇄ 6H
2 O + 3SO
4
2−
E
θ
= 1.76 V
Overall reaction CO(NH
2 )
2 + 3/2O
2 →
N
2 + CO
2 + 2H
2 O
E
θ
= 1.15 V
CO(NH
2 )
2 + 3H
2 O
2 →
N
2 + C
O
2 + 5H
2 O or CO(NH
2 )
2 + 3HO
2
-
+ 3 K
+
→
3KOH + N
2 + CO
2 + 2H
2 O
E
θ
= 1.63 V
CO(NH
2 )
2 + 3H
2 O
2 + 6KOH +
3H
2 SO
4 →
N
2 + CO
2 + 11H
2 O + 3K
2 SO
4
E
θ
= 2.51 V
Reprinted from the journal
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