Table S1.
Source | Fig. no. | Sample identifier | Catalyst type (I or II) | NPMC loading, mg/cm2 | O2/H2 absolute pressure, bar | Reported original mass (A/g) or areal (mA/cm2) or volumetric (A/cm3) current density at 0.8 V | Reported extrapolated mass (A/g) or areal (mA/cm2) or volumetric (A/cm3) current density at 0.8 V | Normalized volumetric current density (measured at 0.8ViR-free, H2/O2 is 1 bar), A/cm3 | Normalized volumetric activity (extrapolated at 0.8ViR-free, H2/O2 is 1bar), A/cm3 |
8 | 8 | Impregnation NCR2 | I | 1 | 1.5/1.5 | 16† | 25 | 3.5‡ | 5.5 |
10 | 2 | A 100% NH3 | I | 1 | 1.5/1.5 | 22† | 30 | 5.2‡ | 7.1 |
11 | 8 | BP_CV1 | I | 1 | 2.56/2.56 | 39† | 88 | 4.6‡ | 10.5 |
15 | 6 | (D) | I | 1 | 1.5/1.5 | 3† | 3 | 0.7‡ | 0.7 |
16 | 6 | (d) | I | 3.8 | 1.5/1.5 | 24§ | 24 | 1.5¶ | 1.5 |
19 | 2 | Large open circles | I | 1 | 1/1 | 18‖ | 99 | 18‖ | 99 |
8 | 10 | Ball milling NCR2 | II | 1 | 1.5/1.5 | 66† | 187 | 16‡ | 44 |
17 | 6 | II | 1.6 | 2/2 | 12‖ | 18 | 4.9†† | 7.4 | |
20 | 3 | Stars | II | 1 | 1/1 | 37‖ | 230 | 37‖ | 230 |
21 | 3 | II | 4 | 1/1 | 20‖ | 130 | 20‖ | 130 | |
22 | S6 | Zn(eIm)2TPI | II | 2.2 | 1/1 | 52‖ | 146 | 52‖ | 146 |
27 | S5 | 10/90 | II | 1 | 1.5/1.5 | 132† | 262 | 31‡ | 62 |
This work | 1 | II | 2 | 1/1 | 60‖ | 450 | 60‖ | 450 |
where P*O2 and P*H2 are the reference pressures (1 bar). ρeff is the effective density of carbon-based, porous NPMC electrode, which is set at 0.4 g/cm3 (19). αc is the cathodic transfer coefficient and is assumed to be 1.
Reported mass activity.
Normalized volumetric current density is converted from the reported mass activity based on the equation above.
Reported areal activity.
Normalized volumetric current density is converted from the reported areal activity based on the equation above.
Reported volumetric activity.
Normalized volumetric current density is converted from the reported data based on the equation above.