Single-Step Synthesis of Silver-Doped Titanium Dioxide: Influence of Silver on Structural, Textural, and Photocatalytic Properties

Enhanced Photocatalytic Efficiency of a Least Active Ag-TiO2 by Amine Adsorption

An Ag-TiO2 photocatalyst with 3.5 atom % silver content, synthesized by a single step sol-gel method, possessed silver nanoparticles (AgNPs; 1-5 nm) on the TiO2 surface, but owing to the nonplasmonic nature of AgNPs and the wide band gap of TiO2, this material exhibited poor activity in a photocatalytic degradation reaction. However, this least active Ag-TiO2 catalyst showed a sudden increase in activity during a photocatalytic amine self-coupling reaction showing the highest activity, which was interpreted as amine (reactant) adsorption-driven activity enhancement. We found that amine adsorption occurred over AgNPs converting into plasmonic AgNPs as well as on the TiO2 surface reducing the band gap and therefore facilitated the visible light excitation and the electron-transfer process efficiently, resulting into overall enhancement in the photocatalytic activity. Thus, a very efficient, stable, and visible light active photocatalyst (amine-adsorbed Ag-TiO2) was developed by simply adsorbing an amine in the least active Ag-TiO2 photocatalyst.

High Pressure Photoreduction of CO2: Effect of Catalyst Formulation, Hole Scavenger Addition and Operating Conditions

The photoreduction of CO2 is an intriguing process which allows the synthesis of fuels and chemicals. One of the limitations for CO2 photoreduction in the liquid phase is its low solubility in water. This point has been here addressed by designing a fully innovative pressurized photoreactor, allowing operation up to 20 bar and applied to improve the productivity of this very challenging process. The photoreduction of CO2 in the liquid phase was performed using commercial TiO2 (Evonink P25), TiO2 obtained by flame spray pyrolysis (FSP) and gold doped P25 (0.2 wt% Au-P25) in the presence of Na2SO3 as hole scavenger (HS). The different reaction parameters (catalyst concentration, pH and amount of HS) have been addressed. The products in liquid phase were mainly formic acid and formaldehyde. Moreover, for longer reaction time and with total consumption of HS, gas phase products formed (H2 and CO) after accumulation of significant number of organic compounds in the liquid phase, due to their consecutive photoreforming. Enhanced CO2 solubility in water was achieved by adding a base (pH = 12–14). In basic environment, CO2 formed carbonates which further reduced to formaldehyde and formic acid and consequently formed CO/CO2 + H2 in the gas phase through photoreforming. The deposition of small Au nanoparticles (3–5 nm) (NPs) onto TiO2 was found to quantitatively influence the products distribution and increase the selectivity towards gas phase products. Significant energy storage in form of different products has been achieved with respect to literature results.

Facile synthesis of mesoporous titanium dioxide doped by Ag-coated graphene with enhanced visible-light photocatalytic performance for methylene blue degradation

A highly efficient and elaborately structured visible-light-driven catalyst composed of mesoporous TiO₂ (MT) doped with Ag⁺-coated graphene (MT-Ag/GR) has been successfully fabricated by a sol–gel and solvothermal method.

Solvothermal preparation of Ag nanoparticle and graphene co-loaded TiO2 for the photocatalytic degradation of paraoxon pesticide under visible light irradiation

Efficient photodegradation and mineralization of paraoxon pesticide by a Ag nanoparticle and graphene co-loaded TiO₂ photocatalyst under visible light irradiation.

Multi-mode photocatalytic degradation and photocatalytic hydrogen evolution of honeycomb-like three-dimensionally ordered macroporous composite Ag/ZrO2

Honeycomb-like 3DOM Ag/ZrO₂was prepared by using PS as template and combined with one-step method of vacuum impregnation, which had both good photocatalytic degradation under multi-modes and ability on photocatalytic hydrogen evolution.