Visible-Light Activated Titania and Its Application to Photoelectrocatalytic Hydrogen Peroxide Production

Abstract

Photoelectrochemical cells have been constructed with photoanodes based on mesoporous titania deposited on transparent electrodes and sensitized in the Visible by nanoparticulate CdS or CdS combined with CdSe. The cathode electrode was an air–breathing carbon cloth carrying nanoparticulate carbon. These cells functioned in the Photo Fuel Cell mode, i.e., without bias, simply by shining light on the photoanode. The cathode functionality was governed by a two-electron oxygen reduction, which led to formation of hydrogen peroxide. Thus, these devices were employed for photoelectrocatalytic hydrogen peroxide production. Two-compartment cells have been used, carrying different electrolytes in the photoanode and cathode compartments. Hydrogen peroxide production has been monitored by using various electrolytes in the cathode compartment. In the presence of NaHCO3, the Faradaic efficiency for hydrogen peroxide production exceeded 100% due to a catalytic effect induced by this electrolyte. Photocurrent has been generated by either a CdS/TiO2 or a CdSe/CdS/TiO2 combination, both functioning in the presence of sacrificial agents. Thus, in the first case ethanol was used as fuel, while in the second case a mixture of Na2S with Na2SO3 has been employed.

Use of Chalcogenide-Semiconductor-Sensitized Titania to Directly Charge a Vanadium Redox Battery

“…The photogenerated electrons which escape recombination are led to the air-diffusion cathode electrode where they participate in oxygen reduction. We have previously found that oxygen reduction by the present PFC is accompanied by substantial hydrogen peroxide production [17]. Therefore, we believe that oxygen reduction in the present case may to a large extent be carried out by the following reaction:…”

“…The photoanode electrode was made by depositing a 10 µm nanoparticulate titania film on an FTO electrode and it was sensitized by a combination of CdS, CdSe and ZnS quantum dots. The whole electrode was made by a standard procedure, which has been repeatedly published in the past, for example, in Reference [17]. In short, CdS quantum dots were formed in the mesostructure of titania by successive ionic layer adsorption and reaction (SILAR, 10 cycles), followed by CdSe formation by chemical bath deposition.…”

“…The PFC functioned by oxygen reduction at the air-breathing (gas diffusion) cathode electrode, which was made of carbon cloth (CC) covered on the inner side by a hydrophobic layer of carbon black (CB). Deposition of the hydrophobic layer followed again a standard protocol [17].…”

Performance Study on Methanol Steam Reforming Rib Micro-Reactor with Waste Heat Recovery

“…However, difficulties in storage and ecological environment transportation of hydrogen persist [13,14]. Liquid fuel reformation is becoming an increasingly important process of hydrogen production for on-board mobile applications [15,16]. The use of bioethanol in the schemes of thermochemical recovery of heat contained in exit flue gases is also an option that was considered [17].…”

Advanced Photocatalytic Materials

“…The sensitization of mesoporous Titania films by nanoparticulate CdS and CdSe, in combination with ZnS passivation was used by T. S. Andrade et al [15] for the fabrication of ZnS/CdSe/CdS/TiO 2 /FTO photoanodes, enabling broad visible light harvesting. These photoelectrodes combined with a Pt-free counter electrode, made of carbon cloth with deposited nanoparticulate carbon, were used for the assembly of a photoelectrochemical cell operating as a Photo Fuel Cell, i.e., without any external bias.…”