Photocathode functionalized with a molecular cobalt catalyst for selective carbon dioxide reduction in water

Abstract

Artificial photosynthesis is a vibrant field of research aiming at converting abundant, low energy molecules such as water, nitrogen or carbon dioxide into fuels or useful chemicals by means of solar energy input. Photo-electrochemical reduction of carbon dioxide is an appealing strategy, aiming at reducing the greenhouse gas into valuable products such as carbon monoxide at low or without bias voltage. Yet, in such configuration, there is no catalytic system able to produce carbon monoxide selectively in aqueous media with high activity, and using earth-abundant molecular catalyst. Upon associating a p-type Cu(In,Ga) Se 2 semiconductor with cobalt quaterpyridine complex, we herein report a photocathode complying with the aforementioned requirements. Pure carbon dioxide dissolved in aqueous solution (pH 6.8) is converted to carbon monoxide under visible light illumination with partial current density above 3 mA cm −2 and 97% selectivity, showing good stability over time.

Hybrid Photocathodes for Carbon Dioxide Reduction: Interfaces for Charge Separation and Selective Catalysis

“…[100,101] However relatively few examples of covalently immobilised CO 2 reduction catalysts on light absorbing photoelectrodes are known. [21,68,75,77,102] An important breakthrough was a study on Re(bpy-PO 3 H 2 )(CO) 3 Cl (12) bound to a mesoporous TiO 2 layer coated on Cu 2 O/AZO/ALD-TiO 2 (ALD = atomic layer deposition, AZO = aluminium-doped zinc oxide). [21] In previous experiments [83] where an unbound Re catalyst (11) was used with a Cu 2 O absorber, electrostatic repulsion between the reduced catalyst intermediates and the polarised semiconductor photoelectrode was proposed to prevent multiple charge transfer and subsequent CO 2 reduction.…”

Recent Advances on Metalloporphyrin‐Based Materials for Visible‐Light‐Driven CO2 Reduction

“…[58][59][60][61] Robert and co-workers reported a photocathode of p-type Cu (In, Ga)Se 2 semiconductor associated with Co quaterpyridine complex, which shows photoelectrocatalytic activity in pure aqueous medium with 97 % selectivity for CO 2 -to-CO reduction. [62] Similarly, metalloporphyrin derivatives can also be anchored on the semiconductors to drive CO 2 photoreduction. Carbon nitride has sufficient amino groups on the surface, which are widely utilized to anchor metalloporphyrin through covalent bond linkage and/or hydrogen bonding interactions.…”

Mechanistic Insights into Co and Fe Quaterpyridine-Based CO2 Reduction Catalysts: Metal–Ligand Orbital Interaction as the Key Driving Force for Distinct Pathways

“…Both catalysts are efficient and selective, meaning both catalysts (or their derivatives) find application in electrochemical [75][76][77] and photoelectrochemical 78 reduction of CO 2 to various products, even to CH 4 (albeit with a low Faradaic efficiency); 79 furthermore, hybrid systems are able to operate efficiently in water. 30,80 Robert et al 75 reported a detailed experimental mechanistic study to investigate the catalytic pathways of both Fe and Co systems. Interestingly, they proposed distinct pathways despite an identical ligand framework (see figures 1 (a) and (b)).…”