Electrocatalytic and Solar-Driven Reduction of Aqueous CO₂ with Molecular Cobalt Phthalocyanine–Metal Oxide Hybrid Materials

Electrolytic and solar-driven reduction of CO2 to CO using heterogenized molecular catalysts are promising approaches toward the production a key chemical feedstock, as well mitigating emissions. Here, we report cobalt phthalocyanine catalyst bearing four phosphonic acid anchoring groups (CoPcP) that can be immobilized on metal oxide electrodes. A hybrid electrode with CoPcP mesoporous TiO2 (mesoTiO2) converts in aqueous electrolyte solution at near-neutral pH (7.3) high selectivity turnover number for (TONCO) 1949 ± 5 after 2 h controlled-potential electrolysis ?1.09 V against standard hydrogen (?550 mV overpotential). In situ UV–visible spectroelectrochemical investigations alluded catalytic mechanism involves non-rate-limiting binding doubly reduced catalyst. Finally, integration mesoTiO2|CoPcP assembly p-type silicon (Si) photoelectrode allowed construction benchmark precious-metal-free photocathode achieves TONCO 939 132 66% (CO/H2 = 1.9) under fully conditions. The electrocatalytic photoelectrochemical (PEC) activities were compared those state art synthetic enzymatic catalysts, demonstrating excellent performance its suitability tandem PEC devices.