Molecular Copper(I)–Copper(II) Photosensitizer–Catalyst Photoelectrode for Water Oxidation

Abstract

Copper(II)-based electrocatalysts for water oxidation in aqueous solution have been studied previously, but photodriving these systems still remains a challenge. In this work, a bis(diimine)copper(I)-based donor−chromophore−acceptor system is synthesized and applied as the light-harvesting component of a photoanode. This molecular assembly was integrated onto a zinc oxide nanowire surface, and upon photoexcitation, chronoamperometric studies reveal that the integrated triad can inject electrons directly into the conduction band of zinc oxide, generating oxidizing equivalents that are then transferred to a copper(II) water oxidation catalyst in aqueous solution, yielding O 2 from water with a Faradaic efficiency of 76%.

Photo‐Catalyzed α‐Arylation of Enol Acetate Using Recyclable Silica‐Supported Heteroleptic and Homoleptic Copper(I) Photosensitizers

“…Ethanol (99 % V/V euro denaturated with 1 % of isopropanol), tetraethylorthosilicate (TEOS, � 99 %, Sigma-Aldrich), ammonium hydroxide (NH 4 OH, 25 % solution in water, Acros Organics), hexadecyltrimethylammonium bromide (CTAB, � 99 %, Sigma Aldrich), anhydrous chloroform (� 99 % with 0.5-1.0 % ethanol as stabilizer, Sigma-Aldrich), anhydrous dimethylformamide (99.8 %, Sigma-Aldrich), 2,9-dimethyl-1,10-phenanthroline (� 98 %, Sigma-Aldrich), palladium on activated carbon (5 % Pd, Acros Organics), hydrazine hydrate (N 2 H 4 .H 2 O, 99.9 %, Acros Organics), triethoxy(3-isocyanatopropyl)silane (95 %, ABCR), DPE-Phos (99 %, Acros Organics), tetrakis(acetonitrile)copper(I) hexafluorophosphate (> 97 %, TCI), acetophenone (98 %, Acros Organics), isopropenyl acetate (99 %, Sigma-Aldrich), p-toluenesulfonic acid (p-TsOH, > 98 %, Sigma-Aldrich), 4-nitrobenzenediazonium tetrafluoroborate (> 98 %, TCI) were commercially available and used as received. 2,9-dimethyl-5-nitro-1,10-phenanthroline (DMP-NO 2 ), [40] 2,9-dimethyl-5-amino-1,10-phenanthroline (DMP-NH 2 ), [40] [Cu-(DPEPhos) 2 ]PF 6 [41] and 1-phenylvinyl acetate [38] were synthesized according to published literature.…”

Heterogenization of Molecular Water Oxidation Catalysts in Electrodes for (Photo)Electrochemical Water Oxidation

“…An alternative approach to avoid changing the properties of the molecular WOCs is the modification of the surface of the (photo)electrodes for subsequent covalent attachment of the WOC [55,[88][89][90]. In this regard, alkoxysilanes with specific end-functional groups (such as amines or pyridine derivatives) have been widely used for surface modifi-cation of several (photo)electrodes, such as TiO 2 [64,89,91,92], ZnO [93][94][95], and SnO 2 [96], due to their simple functionalization surface chemistry [88,90]. For instance, with the 3-aminoproyltriethoxysilane (APTES) moiety, amine groups can be readily displayed on photoelectrode surfaces by hydrolytic condensation, where WOCs can be immobilized at a later stage.…”

Photoelectrochemical Cells with a Pyridine-Anchored Bilayer Photoanode for Water Splitting

“…The carboxylic or phosphate group was used as the anchoring group in all of these examples. An issue of using these anchoring groups is that it is usually troublesome to incorporate these groups in synthesis and the resulting films suffer from poor stability in aqueous media. − In this context, we have recently designed a series of organic molecules with multiple terminal pyridine groups as anchors to link functional molecules to the surface of metal or metallic oxide. − This strategy was used to fabricate stable electrochromic films and photoanodes and photocathodes with excellent stability in aqueous media for the construction of DSPECs for H 2 production. In addition to our efforts, the pyridine anchoring strategy has been employed by others on the investigation of interfacial photocatalytic reactions in recent years. ,− …”

“…Generally, in the construction of a suitable anodic electrode for water oxidation, a photosensitizer and a water oxidation catalyst (WOC) are required and responsible for the absorption of visible-light and the catalytic oxidation of water, respectively . These functional materials are modified on the surface of n-type semiconductors (e.g., TiO 2 ) with the aid of additional anchors such as carboxylic or phosphonic groups. − Sun’s group has reported a TiO 2 photoanode with a coadsorbed ruthenium complex photosensitizer and a ruthenium molecular catalyst to exhibit a high photocurrent density of ca. 1.7 mA/cm 2 .…”