A Noble‐Metal‐Free Heterogeneous Photosensitizer‐Relay Catalyst Triad That Catalyzes Water Oxidation under Visible Light

Abstract

An entirely earth‐abundant chromophore‐relay water oxidation catalyst triad system, which is robust and efficient at neutral pH, is presented. The synthesis involves the coordination of a porphyrin derivative to a bridging Fe(CN)5 group, which is then reacted with Co ions to prepare a covalently linked chromophore–Prussian blue analogue assembly. Light‐driven water oxidation studies in the presence of an electron scavenger indicate that the triad is active and it maintains a steady activity for at least three hours. Transient absorption experiments and computational studies reveal that the Fe(CN)5 group is more than a linker as it takes part in electron‐transfer and co‐operates with porphyrin in the charge separation process.

A Robust, Precious‐Metal‐Free Dye‐Sensitized Photoanode for Water Oxidation: A Nanosecond‐Long Excited‐State Lifetime through a Prussian Blue Analogue

“…Guided by our previous findings, we kept the [Fe(CN) 5 ] fragment and active Co site unchanged and screened various organic ligands (R) featuring a pyridyl group (Figure a). A combination of up‐to‐date quantum chemical calculations showed that, in line with our previous results, the critical LUMO is on the Co−O fragment (Figure a) for the active Co oxo/oxyl species . Moreover, the inclusion of a formal positive charge on the ligand by virtue of quaternized pyridyl salts resulted in a more electrophilic LUMO.…”

“…[Fe–NH 3 ] exhibits a sharp CN peak at 2031 cm −1 , which shifts to a higher wavenumber for [Fe–JG] (ca. 2058 cm −1 ) . The blue shift is evidence for not only the coordination of JG to an iron complex but also the donor–acceptor interaction between the iron site and JG, which plays a critical role in efficient electron transfer.…”

“…It is, therefore, evident that a new chemistry toolbox is necessary for the proper coordination of chromophore and WOC in a three‐dimensional bulk system. Beside metal oxide WOCs, cyanide‐ based extended networks, the so‐called Prussian blue (PB) analogues, (PBAs) have also attracted vigorous attention as potential non‐oxide heterogeneous WOCs due to their diversity, entirely earth‐abundant components, and exceptional stabilities in a wide pH range (from 1 to 13) . In photoconversion applications, PBAs are essentially used as WOCs for efficient extraction of photogenerated holes of a semiconductor photoanode.…”

“…In photoconversion applications, PBAs are essentially used as WOCs for efficient extraction of photogenerated holes of a semiconductor photoanode. We have recently demonstrated that a pentacyanoferrate complex can be used as a bridging group to incorporate an organic chromophore to a PBA structure, thereby forming a robust three‐dimensional triad assembly for the light‐driven water oxidation process …”

Strong Light–Matter Interactions in Au Plasmonic Nanoantennas Coupled with Prussian Blue Catalyst on BiVO4 for Photoelectrochemical Water Splitting

“…In recent studies, we developed a facial route based on oblique angle deposition to synthesize plasmonic nanostructures on a large scale. Moreover, we demonstrated that as a result of the cyanide chemistry, so‐called CoFe‐Prussian blue analog (PBA) is a strong and robust water oxidation catalyst (WOC), when connected to an organic chromophore . Inspired by these studies, herein, we adopt an extendable platform for the realization of a catalyst‐plasmonic architecture to improve the performance of semiconductor photoanodes with a facial and large‐scale compatible design in PEC‐WS.…”