Bifunctional Water Splitting Photoelectrocatalysts Using Flexible Organometallic Complex and Nanographene Multilayer Thin Films

Abstract

In comparison with conventional inorganic photocatalysts, organic photoactive materials are promising photocatalysts owing to their high extinction coefficient and chemical tunability. However, their limited photocatalytic activity, induced by a low relative permittivity with high recombination energy, poses significant challenges. Herein, a highly efficient bifunctional photocatalytic hybrid multilayer electrode is designed by a versatile layer-by-layer (LbL) assembly of nanoscale graphene oxide (nGO) and a ruthenium–terpyridine coordination complex (TPY2Ru). We exploited a synergistic effect between two active components, namely, the generation of photoinduced excitons by TPY2Ru and the facilitation of electron transfer by reducing the recombination rate of the generated electrons by nGO in hybrid electrodes. This photocatalytic electrode exhibits bifunctional activities for water splitting in neutral condition with the highest photoanodic current density of 4.28 μA/cm2 at 1.23 V versus a reversible hydrogen electrode (RHE) and a photocathodic current density of 28.42 μA/cm2 at 0 V versus RHE. Furthermore, the unique combination of hybrid materials enables the development of flexible photocatalytic electrodes with remarkable current density retention after a 1000-cycle durability test. Because of the highly tunable properties of the LbL-assembled multilayer electrodes, we anticipate that this strategy can offer insights into the nanoscale-architecture-controlled engineering of efficient photoelectrodes for future solar-fuel energy devices.

Enhanced Photostability and Photoactivity of Ruthenium Polypyridyl-Based Photocatalysts by Covalently Anchoring Onto Reduced Graphene Oxide

“…Overall, the average lifetime calculated is 213 ns, a value shorter than that of the [Ru(dqpCOOH) 2 ] 2+ complex in both deaerated (2.55 μs) and air-equilibrated acetonitrile (314 ns), also denoting the quenching process. 29 Interestingly, the long component recorded on rGO appears more extended than that in air-equilibrated solution, which might reflect the relatively high rigidity of the ruthenium complexes once grafted on the rGO surface. In addition, the appearance of two decay components could be an indication of different populations of Ru 2+ complex, which present different sensitivity toward the quenching of rGO.…”

“…[Ru­(tpy) 2 ] 2+ complexes likely because the strain induced by the bite angle of the tridentate ligand promotes radiationless decay and population of 3 MC states leading to a comparatively very short lifetime of their excited state, limiting their potential and applicability in photocatalysis . In this regard, the recent incorporation of [Ru­(tpy) 2 ] 2+ complexes into photoactive materials has shown promising enhancement of the hybrid materials’ photocatalytic performance. ,− Wilhelm and co-workers showed significantly improved photocatalytic activity when anchoring a [Ru­(tpy) 2 ] 2+ complex onto graphene oxide (GO) …”

Developments and Perspectives on Robust Nano‐ and Microstructured Binder‐Free Electrodes for Bifunctional Water Electrolysis and Beyond

“…Recently, a tandem cell comprising of an n-type photoanode of n-Se/BiVO 4 and a p-type photocathode of p-Cr 2 O 3 /CuO:Ni could reach a photocurrent of ≈0.04 mA cm −2 at zero bias. [500] Kim et al [501] demonstrated a unique, flexible, and hybrid bifunctional multilayer PEC water splitting photoelectrode composed of nanoscale graphene oxide (nGO) and a terpyridine complex of ruthenium(II) (TPY 2 Ru) on an ITO-coated PET substrate for overall water splitting reaction. To make an efficient PEC system for water splitting, they hosted a TPY 2 Ru to harvest visible light to create more photoinduced electrons as well as nGO to afford photoactive sites for water splitting in the multilayer photoelectrode.…”

Conductive Fibrous Metal‐Cyanoquinone Complexes with Excellent Microwave Absorption and Shielding Effectiveness at Ultrathin Thickness

“…During the past several decades, metal–organic complexes have attracted great attention. By virtue of unique physical and chemical properties, these complexes show great application potential in various areas, such as in energy, [ 22,23 ] catalysis, [ 24,25 ] biomedicine, [ 26 ] and environment treatment. [ 27,28 ] For example, Gorla et al.…”