Shihui Chen. “Transition-metal cation effects on electrodeposited Ni(OH)2 for urea electrolysis.” ChemRxiv (). https://doi.org/10.26434/chemrxiv.15007545/v1

Supporting information is appended to the main paper

Ni(OH)2/NF and transition-metal-containing Ni(OH)2/NF electrode series
XRD (Cu Kα, λ = 1.5418 Å; 2θ = 10–90°; 5° min−1), all patterns Dominated by three strong reflections at approximately 44.5°, 51.9°, and 76.4°
XRD, author assignments (111), (200), and (220) reflections of the NF substrate
XRD, crystalline Ni(OH)2 or secondary-cation-containing phase No distinct diffraction peaks were resolved
Main, pp. 4–6
Representative electrode deposits
SEM (15 kV, 9 mm working distance), Ni(OH)2/NF Interconnected nanosheets and micrometer-scale pores
SEM, representative Fe-containing deposits; nominal 4 % and 8 % bath precursor fractions shown Smaller pores and greater fusion between adjacent features
SEM, Zn-containing deposits; nominal 2 % bath precursor fraction shown Sheet-like morphology with more irregular pores
SEM, Co-containing deposits; nominal 6 % bath precursor fraction shown Finer sponge-like porous texture
SEM, representative Mn-containing deposit; nominal 8 % bath precursor fraction shown Comparatively dense and sheet-like
Main, pp. 4, 6–7
Transition-metal-containing Ni(OH)2/NF electrode series during UOR
EIS (0.1–10⁵ Hz, initiated at 0.45 V vs Hg/HgO), Fe- and Zn-containing series Predominantly single-semicircle responses
EIS (0.1–10⁵ Hz, initiated at 0.45 V vs Hg/HgO), Co- and Mn-containing series An additional relaxation feature
Main, pp. 4, 8–9; SI, p. 17
Ni(OH)2/NF and transition-metal-containing Ni(OH)2/NF electrode series during HER
EIS (0.1–10⁵ Hz, initiated at −1.11 V vs Hg/HgO) Single-semicircle Nyquist responses for all electrodes
Main, pp. 4, 10; SI, p. 20
Ni(OH)2/NF
UOR Cdl, estimated from non-faradaic CVs 0.620 mF
UOR apparent ECSA, estimated using Cs = 0.04 mF cm⁻² 15.5 cm²
HER Cdl, estimated from non-faradaic CVs 0.600 mF
HER apparent ECSA, estimated using Cs = 0.04 mF cm⁻² 15.0 cm²
Main, pp. 4–5, 12–13; SI, pp. 22–24
2 % Fe:Ni(OH)2/NF, nominal bath precursor fraction
UOR Cdl, estimated from non-faradaic CVs 0.839 mF
UOR apparent ECSA, estimated using Cs = 0.04 mF cm⁻² 21.0 cm²
HER Cdl, estimated from non-faradaic CVs 0.701 mF
HER apparent ECSA, estimated using Cs = 0.04 mF cm⁻² 17.5 cm²
Main, pp. 4–5, 12–13; SI, pp. 22–24
4 % Fe:Ni(OH)2/NF, nominal bath precursor fraction
UOR Cdl, estimated from non-faradaic CVs 0.636 mF
UOR apparent ECSA, estimated using Cs = 0.04 mF cm⁻² 15.9 cm²
HER Cdl, estimated from non-faradaic CVs 0.594 mF
HER apparent ECSA, estimated using Cs = 0.04 mF cm⁻² 14.9 cm²
Main, pp. 4–5, 12–13; SI, pp. 22–24
6 % Fe:Ni(OH)2/NF, nominal bath precursor fraction
UOR Cdl, estimated from non-faradaic CVs 0.777 mF
UOR apparent ECSA, estimated using Cs = 0.04 mF cm⁻² 19.4 cm²
HER Cdl, estimated from non-faradaic CVs 0.492 mF
HER apparent ECSA, estimated using Cs = 0.04 mF cm⁻² 12.3 cm²
Main, pp. 4–5, 12–13; SI, pp. 22–24
8 % Fe:Ni(OH)2/NF, nominal bath precursor fraction
UOR Cdl, estimated from non-faradaic CVs 1.090 mF
UOR apparent ECSA, estimated using Cs = 0.04 mF cm⁻² 27.2 cm²
HER Cdl, estimated from non-faradaic CVs 0.648 mF
HER apparent ECSA, estimated using Cs = 0.04 mF cm⁻² 16.2 cm²
Main, pp. 4–5, 12–13; SI, pp. 22–24
2 % Zn:Ni(OH)2/NF, nominal bath precursor fraction
UOR Cdl, estimated from non-faradaic CVs 0.822 mF
UOR apparent ECSA, estimated using Cs = 0.04 mF cm⁻² 20.6 cm²
HER Cdl, estimated from non-faradaic CVs 0.860 mF
HER apparent ECSA, estimated using Cs = 0.04 mF cm⁻² 21.5 cm²
Main, pp. 4–5, 12–13; SI, pp. 22–24
4 % Zn:Ni(OH)2/NF, nominal bath precursor fraction
UOR Cdl, estimated from non-faradaic CVs 0.928 mF
UOR apparent ECSA, estimated using Cs = 0.04 mF cm⁻² 23.2 cm²
HER Cdl, estimated from non-faradaic CVs 0.846 mF
HER apparent ECSA, estimated using Cs = 0.04 mF cm⁻² 21.2 cm²
Main, pp. 4–5, 12–13; SI, pp. 22–24
6 % Zn:Ni(OH)2/NF, nominal bath precursor fraction
UOR Cdl, estimated from non-faradaic CVs 0.931 mF
UOR apparent ECSA, estimated using Cs = 0.04 mF cm⁻² 23.3 cm²
HER Cdl, estimated from non-faradaic CVs 0.810 mF
HER apparent ECSA, estimated using Cs = 0.04 mF cm⁻² 20.3 cm²
Main, pp. 4–5, 12–13; SI, pp. 22–24
8 % Zn:Ni(OH)2/NF, nominal bath precursor fraction
UOR Cdl, estimated from non-faradaic CVs 0.904 mF
UOR apparent ECSA, estimated using Cs = 0.04 mF cm⁻² 22.6 cm²
HER Cdl, estimated from non-faradaic CVs 0.754 mF
HER apparent ECSA, estimated using Cs = 0.04 mF cm⁻² 18.9 cm²
Main, pp. 4–5, 12–13; SI, pp. 22–24
2 % Co:Ni(OH)2/NF, nominal bath precursor fraction
UOR Cdl, estimated from non-faradaic CVs 0.490 mF
UOR apparent ECSA, estimated using Cs = 0.04 mF cm⁻² 12.3 cm²
HER Cdl, estimated from non-faradaic CVs 0.442 mF
HER apparent ECSA, estimated using Cs = 0.04 mF cm⁻² 11.1 cm²
Main, pp. 4–5, 12–13; SI, pp. 22–24
4 % Co:Ni(OH)2/NF, nominal bath precursor fraction
UOR Cdl, estimated from non-faradaic CVs 0.527 mF
UOR apparent ECSA, estimated using Cs = 0.04 mF cm⁻² 13.2 cm²
HER Cdl, estimated from non-faradaic CVs 0.230 mF
HER apparent ECSA, estimated using Cs = 0.04 mF cm⁻² 5.75 cm²
Main, pp. 4–5, 12–13; SI, pp. 22–24
6 % Co:Ni(OH)2/NF, nominal bath precursor fraction
UOR Cdl, estimated from non-faradaic CVs 0.756 mF
UOR apparent ECSA, estimated using Cs = 0.04 mF cm⁻² 18.9 cm²
HER Cdl, estimated from non-faradaic CVs 0.662 mF
HER apparent ECSA, estimated using Cs = 0.04 mF cm⁻² 16.6 cm²
Main, pp. 4–5, 12–13; SI, pp. 22–24
8 % Co:Ni(OH)2/NF, nominal bath precursor fraction
UOR Cdl, estimated from non-faradaic CVs 0.810 mF
UOR apparent ECSA, estimated using Cs = 0.04 mF cm⁻² 20.3 cm²
HER Cdl, estimated from non-faradaic CVs 0.675 mF
HER apparent ECSA, estimated using Cs = 0.04 mF cm⁻² 16.9 cm²
Main, pp. 4–5, 12–13; SI, pp. 22–24
2 % Mn:Ni(OH)2/NF, nominal bath precursor fraction
UOR Cdl, estimated from non-faradaic CVs 0.704 mF
UOR apparent ECSA, estimated using Cs = 0.04 mF cm⁻² 17.6 cm²
HER Cdl, estimated from non-faradaic CVs 0.717 mF
HER apparent ECSA, estimated using Cs = 0.04 mF cm⁻² 17.9 cm²
Main, pp. 4–5, 12–13; SI, pp. 22–24
4 % Mn:Ni(OH)2/NF, nominal bath precursor fraction
UOR Cdl, estimated from non-faradaic CVs 0.801 mF
UOR apparent ECSA, estimated using Cs = 0.04 mF cm⁻² 20.0 cm²
HER Cdl, estimated from non-faradaic CVs 0.707 mF
HER apparent ECSA, estimated using Cs = 0.04 mF cm⁻² 17.7 cm²
Main, pp. 4–5, 12–13; SI, pp. 22–24
6 % Mn:Ni(OH)2/NF, nominal bath precursor fraction
UOR Cdl, estimated from non-faradaic CVs 0.735 mF
UOR apparent ECSA, estimated using Cs = 0.04 mF cm⁻² 18.4 cm²
HER Cdl, estimated from non-faradaic CVs 0.660 mF
HER apparent ECSA, estimated using Cs = 0.04 mF cm⁻² 16.5 cm²
Main, pp. 4–5, 12–13; SI, pp. 22–24
8 % Mn:Ni(OH)2/NF, nominal bath precursor fraction
UOR Cdl, estimated from non-faradaic CVs 0.778 mF
UOR apparent ECSA, estimated using Cs = 0.04 mF cm⁻² 19.5 cm²
HER Cdl, estimated from non-faradaic CVs 0.702 mF
HER apparent ECSA, estimated using Cs = 0.04 mF cm⁻² 17.6 cm²