(521ac) Molecular Catalyst-Functionalized Silicon Photocathode for Aqueous Photoelectrocatalytic CO2 Reduction to Methanol

Recent research has shown that immobilizing cobalt phthalocyanine (CoPc) molecules onto carbon nitride results in high-performance conversion of CO₂ into CO.¹ Building on this, we developed a molecular catalyst-based photocathode that is active for aqueous CO₂ reduction to CO and methanol. The photoelectrode is composed of CoPc molecules anchored on graphene oxide which is integrated via a (3-aminopropyl)triethoxysilane linker to p-type silicon protected by a thin film of titanium dioxide. The photocathode reduces CO₂ to CO with high selectivity at potentials as mild as 0 V versus the reversible hydrogen electrode (vs RHE). Methanol production is observed at an onset potential of −0.36 V vs RHE, and reaches a peak turnover frequency of 0.18 s^-1. To date, this is the only molecular catalyst-based photoelectrode that is active for the six-electron reduction of CO₂ to methanol.²

This work puts forth a strategy for interfacing molecular catalysts to p-type semiconductors and demonstrates state-of-the-art performance for photoelectrochemical CO_­2 reduction to CO and methanol.

References

(1) Shang, B.; Zhao, F.; Choi, C.; Jia, X.; Pauly, M.; Wu, Y.; Tao, Z.; Zhong, Y.; Harmon, N.; Maggard, P. A.; Lian, T.; Hazari, N.; Wang, H., Monolayer Molecular Functionalization Enabled by Acid–Base Interaction for High-Performance Photochemical CO₂ Reduction. ACS Energy Letters 2022, 7 (7), 2265-2272.

(2) Shang, B.; Rooney, C. L.; Gallagher, D. J.; Wang, B. T.; Krayev, A.; Shema, H.; Leitner, O.; Harmon, N. J.; Xiao, L.; Sheehan, C., Aqueous Photoelectrochemical CO₂ Reduction to CO and Methanol over a Silicon Photocathode Functionalized with a Cobalt Phthalocyanine Molecular Catalyst. Angewandte Chemie 2023, 135 (4), e202215213.