Aqueous CO2 Reduction on Si Photocathodes Functionalized by Cobalt Molecular Catalysts/Carbon Nanotubes

• Photoelectrochemical reduction of CO2 is a promising approach for renewable fuel production. We herein report a novel strategy for preparation of hybrid photocathodes by immobilizing molecular cobalt catalysts on TiO2-protected n+-p Si electrodes (Si|TiO2) coated with multiwalled carbon nanotubes (CNTs) by π–π stacking. Upon loading a composite of CoII(BrqPy) (BrqPy=4′,4′′-bis(4-bromophenyl)-2,2′ : 6′,2′′ : 6′′,2′′′-quaterpyridine) catalyst and CNT on Si|TiO2, a stable 1-Sun photocurrent density of −1.5 mA cm−2 was sustained over 2 h in a neutral aqueous solution with unity Faradaic efficiency and selectivity for CO production at a bias of zero overpotential (−0.11 V vs. RHE), associated with a turnover frequency (TOFCO) of 2.7 s−1. Extending the photoelectrocatalysis to 10 h, a remarkable turnover number (TONCO) of 57000 was obtained. The high performance shown here is substantially improved from the previously reported photocathodes relying on covalently anchored catalysts.

Ämnesord

NATURVETENSKAP  -- Kemi (hsv//swe)

NATURAL SCIENCES  -- Chemical Sciences (hsv//eng)

Nyckelord

Carbon dioxide

Catalyst selectivity

Cobalt compounds

Field emission cathodes

Multiwalled carbon nanotubes (MWCN)

Photocathodes

Silicon

Titanium dioxide

Carbon dioxide reduction

CO 2 reduction

Cobalt complexes

Cobalt complexes (III)

Functionalized

Hybrids material

Molecular catalysts

Photocathode

Photoelectrochemicals

]+ catalyst

Hybrid materials

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