Highly Asymmetric Phthalocyanine as a Sensitizer of Graphitic Carbon Nitride for Extremely Efficient Photocatalytic H₂ Production under Near-Infrared Light

Abstract

Highly asymmetric zinc phthalocyanine derivative (Zn-tri-PcNc) with intense near-IR light (650–800 nm) absorption is utilized as a sensitizer to extend the spectral response region of graphitic carbon nitride (g-C3N4) from ∼450 nm to more than 800 nm. Ultraviolet–visible light (UV-vis) diffuse reflectance absorption spectra (DRS), photoluminescence (PL) spectra, time-resolved photoluminescence spectra (TRPS), and energy band structure analyses are adopted to investigate the photogenerated electron transfer process between Zn-tri-PcNc and g-C3N4 on both thermodynamics and dynamics aspects. After optimizing the photocatalytic condition and adding chenodeoxycholic acid (CDCA) as coadsorbent, Zn-tri-PcNc sensitized g-C3N4 photocatalyst shows a H2 production efficiency of 125.2 μmol h–1 under visible/near-IR-light (λ ≥ 500 nm) irradiation, corresponding to a turnover number (TON) of 5008 h–1 with an extremely high apparent quantum yield (AQY) of 1.85% at 700 nm monochromatic light irradiation. The present work should be the rarely fundamental investigation on the utilization of near-IR light of solar radiation for the photocatalytic H2 production from water splitting over a dye-sensitized semiconductor.

Hydrogenated TiO2/SrTiO3 porous microspheres with tunable band structure for solar-light photocatalytic H2 and O2 evolution

“…9. As described in previous reports [24,26], hydrogenation leads to the formation of an isolated band within the band gap, which causes the band edge to red-shift toward the longer wavelength region, indicating a narrowing of the band gap [25,45]. Under visible-light irradiation, the photogenerated electrons in the covalence band of H-TiO2 and H-SrTiO3 are both excited and transferred to the corresponding conduction band (CB) (process 4).…”

Dye-Sensitized Photocatalytic Water Splitting and Sacrificial Hydrogen Generation: Current Status and Future Prospects

“…In one study, they used three widely used electron donors, TEOA, EDTA, and ascorbic acid (AA) to study the hydrogen generation rate over Zn-tri-PcNc/g-C3N4. The results of this study are shown in Figure 16 [62]. It can be observed that the best photoactivity of Zn-tri-PcNc/g-C3N4 was obtained in the presence of AA compared to that of with TEOA and EDTA.…”

“…However, research on other transition metals is very limited compared to Ru-complexes. Metal porphyrins (MPs) and metal phthalocyanines (MPcs) are two notable examples of these metal complexes that have been widely used in dye-sensitization photocatalysis [58][59][60][61][62]. Typical molecular structures and symbols of the metal complexes are shown in Figure 13 [63].…”

“…Recently, Peng's group studied and comprehensively discussed the effect of different electron donors on hydrogen production by dye-sensitized photocatalysis [62,75,83]. In one study, they used three widely used electron donors, TEOA, EDTA, and ascorbic acid (AA) to study the hydrogen generation rate over Zn-tri-P c N c /g-C 3 N 4 .…”

“…Therefore, the association of the oxidized dye might be better with acidic AA than with the basic TEOA leading to better dye regeneration and hydrogen generation. On the other hand, EDTA is known to strongly compete with carboxylic acid-based dyes in adsorption onto TiO 2 surface, resulting in lower hydrogen generation as shown in Figure 16 [62]. regeneration and hydrogen generation.…”