Promoting photocatalytic CO2 reduction with a molecular copper purpurin chromophore

Abstract

CO2 reduction through artificial photosynthesis represents a prominent strategy toward the conversion of solar energy into fuels or useful chemical feedstocks. In such configuration, designing highly efficient chromophores comprising earth-abundant elements is essential for both light harvesting and electron transfer. Herein, we report that a copper purpurin complex bearing an additional redox-active center in natural organic chromophores is capable to shift the reduction potential 540 mV more negative than its organic dye component. When this copper photosensitizer is employed with an iron porphyrin as the catalyst and 1,3-dimethyl-2-phenyl-2,3-dihydro-1H-benzo[d]imidazole as the sacrificial reductant, the system achieves over 16100 turnover number of CO from CO2 with a 95% selectivity (CO vs H2) under visible-light irradiation, which is among the highest reported for a homogeneous noble metal-free system. This work may open up an effective approach for the rational design of highly efficient chromophores in artificial photosynthesis.

Plasmonic Active “Hot Spots”‐Confined Photocatalytic CO2 Reduction with High Selectivity for CH4 Production

“…Photocatalytic reduction of CO 2 with water vapor to hydrocarbon fuels has emerged as a promising route to alleviate both global climate warming and energy shortage issues. [ 1–3 ] Unfortunately, a high dissociation energy of CO bond (750 KJ mol −1 ) pose a grand thermodynamic barrier for the activation and reduction of CO 2 . [ 4,5 ] Although numerous semiconductor materials have been proven to work for CO 2 photoreduction, the development of semiconductors alone as potential photocatalysts still suffers from their inherent limitations on the light harvesting and utilization.…”

Noble metal-free bis-tridentate benzimidazole zinc(ii) and iron(ii) complexes for selective CO2photoreduction

“…5 For example, noble metal complexes such as Re, 6–8 Ru, 9–11 and Ir 12 used as catalysts for CO 2 photoreduction have been investigated extensively, but the high cost of noble metals is often not conducive to large-scale industrial applications. Therefore, in recent years, more and more noble metal-free complexes such as Fe, 13–16 Co, 17–20 Ni, 21–24 Mn, 25,26 Zn 27,28 and Cu 29,30 have been also employed for CO 2 reduction. Additionally, a photocatalytic system composed of non-precious metal catalysts and photosensitizers is strongly attractive in view of cost-effective and sustainable development.…”

Efficient CO2 reduction over a Ru-pincer complex/TiO2 hybrid photocatalyst via direct Z-scheme mechanism

“…These results reveal that CO/CH 4 are derived from the CO 2 RR process rather than the decomposition of other substances in the present system. 22…”

“…18,19 Nevertheless, these homogeneous systems usually have certain limitations, such as the wide variety of possible products, the need for organic solvents and sacrificial reagents, and the difficulty of photocatalyst recovery. 20–22 Recently, a series of rigid pyridyl-based N′NN ′-Ru( ii ) pincer complexes with good homogeneous CO 2 RR ability were prepared by our group. 23–25 Herein, a Ru-pincer complex [Ru(N 3 )(ONO)] bearing a pyridyl-based N ′ NN ′-pincer ligand [N 3 , 2,6-bis(benzimidazol-2-yl)pyridine] and a quinolinyl-based ligand (ONO) was fabricated using [Ru(N 3 )(CH 3 CN) 2 Cl]Cl (RuN 3 ) reacting with 1 equivlent of 2,6-dihydroxyquiniline-2-carboxylic acid (ONO), as shown in Scheme 1, which was then immobilized on TiO 2 nanoparticles and used as the reduction units in a gas–solid photoreaction system for CO 2 RR.…”