TY - JOUR
T1 - Engineering of a highly stable metal-organic Co-film for efficient electrocatalytic water oxidation in acidic media
AU - Younus, H. A.
AU - Vandichel, M.
AU - Ahmad, N.
AU - Ahlberg, E.
AU - Busch, M.
AU - Verpoort, F.
N1 - Publisher Copyright:
© 2020 Elsevier Ltd
PY - 2020/9
Y1 - 2020/9
N2 - Water oxidation is traditionally performed over IrO2 and RuO2 owing to their high stability at low pH compared to molecular O2 evolution catalysts. The low stability of molecular complexes in acids limits their industrial exploitation as anodes in water-splitting devices, where high current densities and proton conductivity are required. Herein, an existing Co(1,10-phenanthroline)2 complex film is engineered to improve its pH-stability via extra OH substituents on the ligand, i.e. 1,10-phenanthroline-4,7-diol. This novel Co(1,10-phenanthroline-4,7-diol)2 complex film is active for water oxidation at low overpotentials and stable at low pH. Since the calculated water oxidation overpotentials of both complexes are similar, the difference in water oxidation activity is attributed to a smaller charge transfer resistance, which originates from a different anchoring style to the electrode via the OH groups of the ligand. This result is supported by electrochemical impedance measurements. The high pH-stability of the Co(1,10-phenanthroline-4,7-diol)2 film is computationally rationalized by a high crystal formation energy observed in DFT calculations. In summary, an acid-stable and active cobalt-based metal-organic film is reported that competes well with most reported earth-abundant catalysts for water oxidation under similar conditions.
AB - Water oxidation is traditionally performed over IrO2 and RuO2 owing to their high stability at low pH compared to molecular O2 evolution catalysts. The low stability of molecular complexes in acids limits their industrial exploitation as anodes in water-splitting devices, where high current densities and proton conductivity are required. Herein, an existing Co(1,10-phenanthroline)2 complex film is engineered to improve its pH-stability via extra OH substituents on the ligand, i.e. 1,10-phenanthroline-4,7-diol. This novel Co(1,10-phenanthroline-4,7-diol)2 complex film is active for water oxidation at low overpotentials and stable at low pH. Since the calculated water oxidation overpotentials of both complexes are similar, the difference in water oxidation activity is attributed to a smaller charge transfer resistance, which originates from a different anchoring style to the electrode via the OH groups of the ligand. This result is supported by electrochemical impedance measurements. The high pH-stability of the Co(1,10-phenanthroline-4,7-diol)2 film is computationally rationalized by a high crystal formation energy observed in DFT calculations. In summary, an acid-stable and active cobalt-based metal-organic film is reported that competes well with most reported earth-abundant catalysts for water oxidation under similar conditions.
KW - DFT
KW - Electrocatalysts
KW - Molecular catalysts
KW - Organometallic film
KW - Oxygen evolution reaction (OER)
KW - Water splitting
UR - http://www.scopus.com/inward/record.url?scp=85084824159&partnerID=8YFLogxK
U2 - 10.1016/j.mtener.2020.100437
DO - 10.1016/j.mtener.2020.100437
M3 - Article
AN - SCOPUS:85084824159
SN - 2468-6069
VL - 17
JO - Materials Today Energy
JF - Materials Today Energy
M1 - 100437
ER -