Highly Efficient Visible‐Light‐Induced Photocatalytic Hydrogen Production via Water Splitting using FeCl₃‐Based Ionic Liquids as Homogeneous Photocatalysts

Abstract

The ionic liquid (IL) 1‐octyl‐3‐methylimidazolium bromide/FeCl3 [OMIM]Br/FeCl3 was prepared with three molar ratios of [OMIM]Br/FeCl3 (0.5 : 1, 1 : 1, and 2 : 1), and fully characterized through 1H and 13C NMR, Fourier‐transform IR, and Raman spectroscopic techniques. The optical properties of the prepared [OMIM]Br/FeCl3 ILs were revealed via diffuse reflectance and photoluminescence spectra. The photocatalytic activity of [OMIM]Br/FeCl3 ILs as homogenous photocatalysts were investigated towards hydrogen generation from methanol/water mixtures under visible light irradiation. The FeCl3‐based IL with [OMIM]Br/FeCl3 molar ratio of 1 : 1 exhibited the highest visible light photocatalytic activity with a hydrogen productivity of 243.2 mmol h−1 g−1 and a hydrogen purity of 95.5 %; such a high hydrogen yield and purity was reported for the first time. It was proposed that [OMIM] Br acted as an electron acceptor, which delayed the electron‐hole pair recombination of FeCl3. Also, [OMIM] Br could capture the produced carbon dioxide that is released with hydrogen gas. Additionally, [OMIM] Br/FeCl3 could be reused six times with nearly the same photocatalytic activity. These outstanding credits in terms of hydrogen generation rate and purity plus the economic feasibility, through several cycles of reuse, could certify such an IL as a promising photocatalyst for employment in water splitting. This paper suggests ways forward for research to develop the use of ILs as efficient and effective photocatalysts for hydrogen generation via water splitting.

Physico‐Chemical Properties of Magnetic Dicationic Ionic Liquids with Tetrahaloferrate Anions

“… [41] UV‐Vis reflectance spectra (Figure S30) also demonstrated the characteristic absorption band edges around 620 nm for [FeCl 3 Br] − and these results correspond very well with the literature. [47] …”

“…[41] UV-Vis reflectance spectra (Figure S30) also demon- strated the characteristic absorption band edges around 620 nm for [FeCl 3 Br] À and these results correspond very well with the literature. [47] The strength of the ionic interaction between the cation and anion influences the melting point of ionic liquids. [48] The lattice energy depends on the molecular symmetry, intermolecular forces of attraction, and conformational degrees of freedom.…”

Poly N-(2-aminoethyl) acrylamide-NiO composite as novel efficient photocatalyst for desulfurization of diesel fuel under visible-light irradiation

“…The reduced band gap value for the composite than NiO is attributed to the incorporation of the polymer which is a structure of a high electron density. The presence of the polymer electrons could in turn shift the valence band electrons of NiO to higher sub-energy level [26]. Therefore, the band gap value could be reduced to less than 3.25 in the case of the produced composite by mixing NiO and polymer.…”

“…The displayed data could reveal that the time increase from 60 to 90 min could enhance the desulfurization level by nearly 25 %. This observation can be explained by increasing the probability of interaction between the effective sites of the photocatalyst and the substrate [26] (sulfur compounds in diesel fuel) by increase of reaction time.…”

Photocatalytic Degradation of Congo Red Dye via Multi-Walled Carbon Nanotubes Modified CuO and ZnO Nanoparticles under Visible Light Irradiation

“…intensity increases with increasing the number of emitted electrons resulting from the rapid recombination between excited electrons and holes, which, in turn, reduces the photo-activity of the catalyst. The wavelength of emission is directly correlated to the energy band-gap due to the recombination of a photo-generated hole with an electron occupying the oxygen vacancy [52,53].…”