“…Based on this analysis, anode reaction with a more negative standard reduction potential (SRP, Table S1, Supporting Information) is essential, which can be satisfied by a series of metals as listed in the SRP. Zinc (Zn) has been selected to construct the fuel cell for the concept demonstration, [ 24 ] with further consideration of cost and stability in basic solution as illustrated by our patent and Guo's resent work. [ 24,25 ] Specifically, it offers a reduction potential of −1.26 V versus NHE, i.e normal hydrogen electrode (pH14, Equation ()), achieving theoretical energy density E theo = 910 Wh Kg –1 with NO 3 – feedstock converted to NH 4 + (pH14), which can be even higher (as high as to 1754 Wh Kg –1 ) if coupled with lower cathode chamber pHs (detailed in the Supporting Information and Table S2, Supporting Information).…”