Hydrogen gas generation using a metal-free fluorinated porphyrin

Abstract

Free-base meso-tetra(pentafluorophenyl)porphyrin, 1, is electrocatalytically active for hydrogen gas generation in the presence of p-toluenesulfonic acid.

Recent advances in the mechanisms of the hydrogen evolution reaction by non-innocent sulfur-coordinating metal complexes

“…In particular, the deuterium kinetic isotope effect (KIE = k H /k D ), where k H is the rate of proton reduction and k D the rate of catalytic reduction of a deuterated acid, is considered an essential tool for the study of H 2 evolution reaction mechanisms. A large KIE indicates a ligand centred process, [99][100][101] while an inverse value KIE < 1 is consistent with a metal hydride intermediate. 96,102 A multiproton and multielectron electrocatalytic reaction may involve several protonation and oxidation states with different solubility and stability.…”

Synthetic Organic Design for Solar Fuel Systems

“…[31] Af ree-base porphyrin (P2H) bearing four electron-withdrawing meso-tetra(pentafluorophenyl) groups (12,F igure 7) achieved H 2 production. [32] Cyclic voltammetry conducted in THF featured two reversible 1-e À reductions at E 1/2 = À1.14 and À1.54 Vv s. ferrocene/ferrocenium (Fc/Fc + ). Upon addition of tosic acid, the first reduction wave remained unchanged, while an enhanced wave appears at À1.31 Vvs.…”

Molecular Catalysts Immobilized on Semiconductor Photosensitizers for Proton Reduction toward Visible‐Light‐Driven Overall Water Splitting

“…Molecular catalysts in homogenous and heterogeneous systems have been developed rapidly during the last few decades, showing promising applications in the proton reduction reaction producing hydrogen . Organic and organometallic catalysts were usually applied in the reductive halfreaction of the light‐driven hydrogen generation by proton reduction.…”

“…Depending on the existence of a metal atom at the center of the ring, they are subcategorized as metal‐free and metal porphyrins. In metal‐free porphyrins, the covalent N−H bond of the pyrrole is considered to be the active site . In metal porphyrins, nitrogen atoms at the center bind with many metallic elements including Fe, Ni, and Co, forming a stable complex.…”

“…As mentioned in the previous section, metal‐free porphyrins form covalent N−H bonds, which are active for electrochemical reductive reactions. Moreover, the four nitrogen atoms at the porphyrin core are suitable for coordinating protons to produce H 2 with reduced activation energy because the configurations are believed to prearrange the transition state for formation of H−H bond . The mechanism by which H 2 is generated by proton reduction should be different depending on the structure of each molecular catalyst, but the details are not clearly understood.…”