Photocatalysis

About: Photocatalysis is a research topic. Over the lifetime, 67088 publications have been published within this topic receiving 2145233 citations. The topic is also known as: photocatalyst.

Sub-10 nm rutile titanium dioxide nanoparticles for efficient visible-light-driven photocatalytic hydrogen production

Abstract: Titanium dioxide is a promising photocatalyst for water splitting, but it suffers from low visible light activity due to its wide band gap Doping can narrow the band gap of titanium dioxide; however, new charge-carrier recombination centres may be introduced Here we report the design of sub-10 nm rutile titanium dioxide nanoparticles, with an increased amount of surface/sub-surface defects to overcome the negative effects from bulk defects Abundant defects can not only shift the top of the valence band of rutile titanium dioxide upwards for band-gap narrowing but also promote charge-carrier separation The role of titanium(III) is to enhance, rather than initiate, the visible-light-driven water splitting The sub-10 nm rutile nanoparticles exhibit the state-of-the-art activity among titanium dioxide-based semiconductors for visible-light-driven water splitting and the concept of ultra-small nanoparticles with abundant defects may be extended to the design of other robust semiconductor photocatalysts

Tuning Oxygen Vacancies in Ultrathin TiO2 Nanosheets to Boost Photocatalytic Nitrogen Fixation up to 700 nm

Abstract: Dinitrogen reduction to ammonia using transition metal catalysts is central to both the chemical industry and the Earth's nitrogen cycle. In the Haber-Bosch process, a metallic iron catalyst and high temperatures (400 °C) and pressures (200 atm) are necessary to activate and cleave NN bonds, motivating the search for alternative catalysts that can transform N2 to NH3 under far milder reaction conditions. Here, the successful hydrothermal synthesis of ultrathin TiO2 nanosheets with an abundance of oxygen vacancies and intrinsic compressive strain, achieved through a facile copper-doping strategy, is reported. These defect-rich ultrathin anatase nanosheets exhibit remarkable and stable performance for photocatalytic reduction of N2 to NH3 in water, exhibiting photoactivity up to 700 nm. The oxygen vacancies and strain effect allow strong chemisorption and activation of molecular N2 and water, resulting in unusually high rates of NH3 evolution under visible-light irradiation. Therefore, this study offers a promising and sustainable route for the fixation of atmospheric N2 using solar energy.

An Amorphous Carbon Nitride Photocatalyst with Greatly Extended Visible-Light-Responsive Range for Photocatalytic Hydrogen Generation.

Abstract: Amorphous carbon nitride (ACN) with a bandgap of 1.90 eV shows an order of magnitude higher photocatalytic activity in hydrogen evolution under visible light than partially crystalline graphitic carbon nitride with a bandgap of 2.82 eV. ACN is photocatalytically active under visible light at a wavelength beyond 600 nm.

Photolysis of chloroform and other organic molecules in aqueous titanium dioxide suspensions

Abstract: The photocatalytic degradation of chloroform has been investigated in aqueous suspensions of TiO_2 over the wavelength range of 310-380 nm. A detailed reaction mechanism has been proposed in which the rate-determining step is the reaction of surface-bound *OH with adsorbed CHCl_3. A pH-stat titration technique was developed for the measurement of the rates of degradation of chlorinated hydrocarbons. The quantum efficiency (Ф = 0.56 at ⋋ = 330 nm) of the degradation of CHCl_3, was found to be inversely proportional to the square root of the incident light intensity. This relationship can be explained in terms of a direct competition between a second-order recombination of surface-bound 'OH and the rate-determining reaction of surface-bound 'OH with CHCl_3. The rates of degradation of several electron donors have been correlated with their computed surface speciation. The results of this study show that the adsorption of electron donors and acceptors to the TiO_2 surface plays a more important role in determining the rate of the photocatalytic reactions than the effect of pH-dependent Fermi-level shifts.