Supplementary Information
Improved Performance of Co3O4/C by the Simple Solvothermal Method as an Electrocatalyst for Oxygen Reduction Reaction in Alkaline Solution
IONICS
Yingbin Huang,† Min Zhang‡, Peng Liu‡ , Lishi Wang†*, Faliang Cheng‡#
† School of Chemistry and Chemical Engineering, South China University of Technology, Guangzhou 510641, People's Republic of China
‡Guangdong Engineering and Technology Research Center for Advanced Nanomaterials, Dongguan 523808, People's Republic of China
*
#
Fig.S1 RDE Voltammograms of the condition from 1 to 18 in oxygen-saturated 0.1M KOH solution
at a rotation speed of 1400 rpm with a scan rate of 10 mV s-1
Fig.S2 Chronoamperometric responses (percentage of current retained versus operation time) of condition from 1 to 18 at -0.35V vs SCE in oxygen-saturated 0.1M KOH solution at a rotation speed of 500 rpm
Table S1 Randomized factors’ levels of orthogonal experimental synthesising MCo2X4/C
precipitant A / water and ethylene glycol (mL) B / metal component C / solvothermal temperature D / calcining temperature E
1 / urea / 0 + 10 / 3Co / 160°C / 300°C
2 / thiourea / 1 + 9 / Mn + 2Co / 200°C / 350°C
3 / - / 2 + 8 / Ni + 2Co / 180°C / no calcining
Table S2 Disposition and result of orthogonal experimental synthesising MCo2X4/C
condition / factors / jL a(mA cm–2) / P b
(%)
A / B / C / D / E
1 / urea / 0 + 10 / 3Co / 180°C / 350°C / –4.09606 / 99.7
2 / urea / 1 + 9 / 3Co / 160°C / 300°C / –3.51882 / 94.4
3 / urea / 2 + 8 / 3Co / 200°C / no / –3.72522 / 90.8
4 / urea / 0 + 10 / Mn + 2Co / 200°C / 300°C / –3.8076 / 94.5
5 / urea / 1 + 9 / Mn + 2Co / 180°C / no / –3.42587 / 74.5
6 / urea / 2 + 8 / Mn + 2Co / 160°C / 350°C / –3.64689 / 89.2
7 / urea / 0 + 10 / Ni + 2Co / 160°C / no / –2.68387 / 76.1
8 / urea / 1 + 9 / Ni + 2Co / 200°C / 350°C / –3.59311 / 97.0
9 / urea / 2 + 8 / Ni + 2Co / 180°C / 300°C / –3.68792 / 88.7
10 / thiourea / 0 + 10 / 3Co / 160°C / 300°C / –3.80791 / 118.3
11 / thiourea / 1 + 9 / 3Co / 200°C / no / –3.82469 / 98.7
12 / thiourea / 2 + 8 / 3Co / 180°C / 350°C / –3.96582 / 108.5
13 / thiourea / 0 + 10 / Mn + 2Co / 180°C / no / –3.87878 / 91.5
14 / thiourea / 1 + 9 / Mn + 2Co / 160°C / 350°C / –3.59342 / 95.8
15 / thiourea / 2 + 8 / Mn + 2Co / 200°C / 300°C / –4.11876 / 74.9
16 / thiourea / 0 + 10 / Ni + 2Co / 200°C / 350°C / –3.65186 / 86.1
17 / thiourea / 1 + 9 / Ni + 2Co / 180°C / 300°C / –3.68139 / 92.8
18 / thiourea / 2 + 8 / Ni + 2Co / 160°C / no / –3.25335 / 72.0
Footnotes:
a: limited diffusion current density at –0.70 V vs SCE measured by linear sweep voltammetry at 1400 rpm with a scan rate of 10 mV s–1 in O2-saturated 0.1 M KOH
b: retained current percentage measured after 1 h chronoamperometry test at –0.35 V vs SCE at 500 rpm in O2-saturated 0.1 M KOH
Table S3 Range analysis data of the limited current density
A / B / C / D / E / grand meanJ1j / –3.576 / –3.654 / –3.823 / –3.417 / –3.770 / –3.665
J2j / –3.753 / –3.606 / –3.745 / –3.787 / –3.758
J3j / – / –3.733 / –3.425 / –3.789 / –3.465
Rj / 0.177 / 0.127 / 0.398 / 0.372 / 0.305
Data analysis was carried out through the range analysis to reflect the optimal reaction conditions and their magnitudes. Table S3 is the range analysis of limited diffusion current density. The data are originated from Table S2. Jij is defined as the mean of the limited current density (jL) of each level (i) respectively in each factor (j). Rj, which represents the range between the maximum and minimum value of Jij in each factor, is used for evaluating the importance of the factors on the limited diffusion current density.