First Study on Phosphonite-Coordinated Ruthenium Sensitizers for Efficient Photocatalytic Hydrogen Evolution

Abstract

For the first time we report the design and syntheses of phosphonite coordinated ruthenium(II) sensitizers bearing ĈN̂N ligand and/or terpyridine derivatives carboxylate anchor (GS11, GS12. and GS13) and its application for hydrogen production over Pt-TiO2 system. These heteroleptic complexes exhibit broad metal-to-ligand charge transfer transition band over the whole visible regime extending up to 900 nm. DFT calculations of these complexes show that the HOMO is distributed over the Ru and Cl atom whereas; LUMO is localized on the polypyridile ligand, which are anchored on TiO2 surface. Among the sensitizers tested for photocatalytic hydrogen evolution, GS12 exhibited a maximum turnover number (TON) 8605 (for 8 h), which is very high compared to the reference sensitizer (N719) with TON 163 under similar evaluation condition. The dependence of the hydrogen evolution rate at different pH using GS11, GS12, GS13, and DX-1-sensitized Pt-TiO2 has been studied and the maximum H2 production yield was obtained at pH 7 for all sensitizers.

Chlorosome‐Like Molecular Aggregation of Chlorophyll Derivative on Ti3C2Tx MXene Nanosheets for Efficient Noble Metal‐Free Photocatalytic Hydrogen Evolution

“…[ 11 ] Photocatalytic hydrogen evolution reaction (HER) are mainly based on inorganic semiconductor and polymer‐based organic semiconductors, for exampl, in a conventional dye‐sensitized semiconductor photocatalytic hydrogen production system, the dye molecules are excited to inject electrons into the conduction band of a semiconductor or polymer (inorganic semiconductor TiO 2 or g ‐C 3 N 4 is usually chosen), then the electrons are quickly captured by the co‐catalyst (such as precious metals Pt, Ru, and Pd), and finally the electrons combine with H + in the water to produce hydrogen. [ 12–16 ]…”

Visible Light-Driven Dye-Sensitized Photocatalytic Hydrogen Production by Porphyrin and its Cyclic Dimer and Trimer: Effect of Multi-Pyridyl-Anchoring Groups on Photocatalytic Activity and Stability

“…Further, modifying the dye is an effective method for transferring electrons from the dye to the photocatalyst. Several studies have investigated efficient light absorption systems; for example, π-conjugated systems, such as phthalocyanines, − xanthene dyes, − donor–acceptor type systems, , and metal–ligand charge transfer type dyes, including ruthenium complexes, exhibit an extensive visible absorption band for ensuring that efficient light absorption can be achieved with respect to charge transfer to the photocatalyst. Further, the electrons are mostly used in an efficient manner at the hydrogen generation site of the photocatalyst if the lifetime of the charge separation state between the dye and the catalyst is considerably long, and this can be accomplished by inserting a π-conjugated system into the dye structure .…”

Dye‐Sensitized Heterogeneous Photocatalysts for Green Redox Reactions

“…The resulting compounds exhibited very broad UV/Vis spectra with onsets in the near‐infrared region (NIR), albeit with only moderate molar extinction coefficients. Despite that, high activities were recorded in the H 2 generation reaction in combination with Pt/TiO 2 and TEOA at neutral pH, reaching a maximum TON exceeding 8600 in only 8 h of irradiation (light intensity was around 2 Sun) . Modulation of the optical and electrochemical properties of the dyes was also obtained by changing substituents on the structure of terpyridine‐thiocyanate ruthenium complexes (such as MC113 , Figure ).…”

“…Despite that, high activities were recorded in the H 2 generation reaction in combination with Pt/TiO 2 and TEOA at neutral pH, reaching a maximum TON exceeding 8600 in only 8 h of irradiation (light intensity was around 2 Sun). [68] Modulation of the optical and electrochemical properties of the dyes was also obtained by changing substituents on the structure of terpyridine-thiocyanate ruthenium complexes (such as MC113, Figure 8). They presented panchromatic absorption up to 750 nm, accompanied by appropriate HOMO and LUMO positions to ensure smooth electron transfer to the semiconductor and dye regeneration.…”