Role of Methanol Sacrificing Reagent in the Photocatalytic Evolution of Hydrogen

Abstract

The contribution of methanol (CH 3 OH) sacrificing reagent to the photocatalytic evolution of H 2 from aqueous solutions has been studied by tracing the reaction of D 2 O over a Cu/S-TiO 2 catalyst under UV illumination. Use of D 2 O/ CH 3 OH produced higher formation rates of HD and D 2 than that of H 2 . The low H 2 formation rates indicate that the direct reaction of CH 3 OH with photogenerated holes does not proceed to an appreciable extent in the presence of high concentrations of D 2 O. The role of CH 3 OH in accelerating hydrogen formation can be attributed to its ability to produce an electron donor, injecting its electrons to the conduction band.

Reduced Graphene Oxide–Ag3PO4 Heterostructure: A Direct Z‐Scheme Photocatalyst for Augmented Photoreactivity and Stability

“…In this mechanism,t he photogenerated e À in the CB of Ag 3 PO 4 recombines with h + in the VB of RGO [Eq. [61,62] This is in strong agreement with the Z-scheme reported by Xie et al [43] and Yu et al [63] for hydrogen evolution and dyedegradation, respectively. (5) and (6)].…”

Urea‐Modified Carbon Nitrides: Enhancing Photocatalytic Hydrogen Evolution by Rational Defect Engineering

“…These performance metrics are summarized in Table S3 (Supporting Information); the action spectra of the three catalysts are shown in Figure 2b. [27] Furthermore, we have also observed that a number of photocatalysts exhibiting high activity with triethanolamine perform poorly with other electron donors such as methanol (Table S4, Supporting Information). [24] Note that higher quantum yields are generally obtained when triethanolamine is used due to its more reductive potential, current doubling and other effects; [25] we nonetheless did not select this electron donor for activity benchmarking as it is light sensitive, often contains optical impurities, and has a complex photo-oxidation mechanism involving many intermediates, [26] as compared to the well-studied, clean photooxidation of methanol.…”

Hydrogen Production from Aqueous Methanol Solutions Using Ti–Zr Mixed Oxides as Photocatalysts under UV Irradiation

“…where Eg is the band gap energy; hv is the photon energy (h is the Plank's constant and v the frequency of the incident photons); A is a proportional constant. The value of n is determined accordingly to the type of optical transition, being n = 1 or 4 for direct or indirect transition, respectively [25]. In the case of TiO 2 and ZrO 2 , which are indirect band semiconductors, the value of n is equal to 4.…”