Morphology Control of Supramolecular Assembly for Superior CO₂Photoreduction

Abstract

Coordination-driven metallo-supramolecular assemblies are potentially efficient catalysts in photocatalytic CO2 reduction. However, the relationship between morphology and photocatalytic performance remains barely explored. In this work, three metallo-supramolecular assemblies composed of Zn2+ and a flexible tris(terpyridine) ligand have been prepared for noble metal-free CO2 photoreduction on the basis of metal–ligand coordination, hydrogen bonding, and π–π stacking. The three assemblies possess distinct self-assembled morphologies including spherical particle, fibrous-like gel, and microrod. It has been found that the fibrous-like gel exhibits the best catalytic performance in photoreduction of CO2 to CO with a yield of 6.3 mmol g–1 h–1 and 94.7% selectivity over H2 generation. Photoelectrochemical measurements, photoluminescence quenching experiments, and UV–vis absorption spectroscopy studies have demonstrated that the ligand-based electron transfer of the gel is more efficient compared with the other two assemblies.

Unveiling dual catalysis enhancement of a pyridinium-containing Zn(ii) coordination polymer in aerobic photooxidation of organic substrates and selective photoreduction of CO2

“…To compare with other redox potentials conveniently, CB potentials of Py3tpyZn and Ph3tpyZn are also given as −0.68 and −0.98 V vs. NHE (E(NHE) = E(SCE) + 0.24 V). 20,47 As shown in Fig. 2, CB potentials of Py3tpyZn and Ph3tpyZn are both more negative than redox potentials of E(CO 2 /CO) (−0.53 V) and E(O 2 /O 2 c − ) (−0.33 V).…”

“…Initially, the photocatalytic CO 2 reduction experiment was conducted with Py3tpyZn as the catalyst and triethylamine (TEA) as the sacricial electron donor in the presence of an organic photosensitizer 1,2,3,5-tetrakis(carbazol-9-yl)-4,6-dicyanobenzene (4CzIPN) that we have recently used in CO 2 photoreduction. 20,[52][53][54] As shown in Table S2, † 1.23 mmol of CO was generated and only 0.05 mmol of H 2 was found, giving a high selectivity of 96%. Liquid products were not detected by 1 H NMR spectroscopy.…”

“…The electron migration from the photosensitizer to Py3tpyZn may also be realized through other 4CzIPN-related species such as 4CzIPN* or 4CzIPNc − *. 20,41,54,63 As a result, the terpyridine unit and pyridinium unit in Py3tpyZn are reduced into the corresponding radical anion and radical species, respectively. This is consistent with the observation in Fig.…”

“…[17][18][19] Besides, photoreduction of CO 2 can generate value-added chemicals such as CO, CH 4 , CH 3 OH, and HCOOH under mild conditions, and shows potential in producing solar fuels and alleviating global warming. [20][21][22][23][24][25] In this context, numerous catalysts have been established for aerobic photooxidation of organic substrates and photoreduction of CO 2 . These catalysts are basically investigated in either photooxidation or photoreduction reactions.…”

Trinuclear Fe Clusters for Highly Efficient CO2 Photoreduction

“…This shows that individual clusters have better catalytic activity than the corresponding MOFs. Many studies have demonstrated that the morphology of a catalyst can affect its catalytic activity, which is related to the exposure of active sites. ,− The better catalytic activity of clusters compared to MOFs is due to the fact that individual clusters are homogeneous catalysts conducive to active catalytic sites contacting with PS and reactants. The reactants and products are dissolved in the solution in common catalytic reactions.…”