Photocatalytic H₂ Evolution Using a Ru Chromophore Tethered to Six Viologen Acceptors

Abstract

A new photo-charge separator (PCS) consisting of a [Ru(bpy) ] (bpy=2,2'-bipyridine) chromophore and six viologen (MV ) acceptors, [Ru(bpyMV2) ] , is synthesized and its application in the photocatalytic H evolution reaction is reported. The present PCS possesses shorter linkers for connecting the Ru chromophore and the MV acceptors in comparison with our previous PCSs (Inorg. Chem. Front., 2016, 3, 671-680) and shows a consecutive photo-driven electron transfer in the presence of a sacrificial electron donor [ethylenediaminetetraacetic acid (EDTA)], leading to a multi-electron storage over the PCS. This behavior can also be coupled with the catalytic H evolution by the presence of a colloidal Pt catalyst. More importantly, the present PCS exhibits a much higher durability during the photolysis, which is attributed to the higher rate in the catalytic process. The high durability is also attributed to its bulky framework preventing undesirable side reactions.

Enhancement of Photocatalytic Activity for Hydrogen Production by Surface Modification of Pt‐TiO2 Nanoparticles with a Double Layer of Photosensitizers

“…[26][27][28][29] To construct highly active Z-schemew ater-splittingp hotocatalysts, the charge separation efficiency in the DSP mustb ei mproved, and the selective recognition of oxidized or reducedm ediators is importantf or achieving one-way electront ransfer from the oxygen evolutionp hotocatalyst to hydrogen evolution photocatalyst. Althoughm ost studies of DSPsh ave been conducted in the presence of sacrificial electron donators to promote the water-splittingh alf reaction, [30][31][32][33][34][35] there have been several reports concerning water reduction or overallw ater splitting in the presence of redox-reversible electron mediators. [36,37] In 1993,M allouk and co-workers achieveda na pparentq uantum yield (AQY) of 0.3 %u sing aR u II photosensitizer (PS) immobilized on the surface of aw ater reduction catalyst, Pt/ H x K 4Àx Nb 6 O 17 ,w ith iodide as ar edox-reversible electron donor.…”

Proton-coupled multi-electron transfer and its relevance for artificial photosynthesis and photoredox catalysis

“…In this context, recent work on dendrimer-like systems by Sakai and coworkers seems noteworthy. 95,96 By using bpy ligands with covalently attached methyl viologen acceptors and sacrificial reagents, these researchers achieved multi-electron storage, and in presence of Pt colloids catalytic H 2 evolution was observed. Conceptually this is related to earlier work on electron accumulation with sacrificial reagents by MacDonnell, Campagna, and various other research groups.…”

Efficient Photoinduced Electron Transfer from Pyrene‐o‐Carborane Heterojunction to Selenoviologen for Enhanced Photocatalytic Hydrogen Evolution and Reduction of Alkynes

“…During the past several decades, the photosensitizers have been gained significant progress, lots of photosensitizers, such as nanoparticles, [ 12 , 13 , 14 ] organic dyes [ 15 , 16 , 17 ] and [Ru(bpy) 3 ] 2+ derivatives, [ 18 , 19 ] etc. have been reported, [ 20 ] which showed good light absorption properties in the photocatalytic system.…”

“…[ 21 , 22 , 23 ] Among the rarely reported electron mediator, viologen (MV 2+ ) was considered as ideal electron transfer agent for photocatalytic reaction due to its multiple redox states and electron accepting properties. [ 19 , 24 ] For instance, MV 2+ can accept electrons from [Ru(bpy) 3 ] 2+ or g‐C 3 N 4 accompany with the formation of radical cations (MV +• ) via photoinduced electron transfer (PET) process, followed with HER on Pt‐based catalyst ( Figure 1 a ). [ 25 , 26 ] However, the multi‐step electron transfer from photosensitizer to electron mediator to catalyst greatly reduces the utilization of electrons, thereby reducing the efficiency of photocatalytic reactions.…”