ABSTRACT
The development of highly efficient and robust photocatalysts has attracted great attention for solving the global energy crisis and environmental problems. Herein, we describe the synthesis of a p-n heterostructured photocatalyst, consisting of ZnO nanorod arrays (NRAs) decorated with BiOI nanoplates (NPs), by a facile solvothermal method. The product thus obtained shows high photoelectrochemical water splitting performance and enhanced photoelectrocatalytic activity for pollutant degradation under visible light irradiation. The p-type BiOI NPs, with a narrow band gap, not only act as a sensitizer to absorb visible light and promote electron transfer to the n-type ZnO NRAs, but also increase the contact area with organic pollutants. Meanwhile, ZnO NRAs provide a fast electron-transfer channel, thus resulting in efficient separation of photoinduced electron-hole pairs. Such a p-n heterojunction nanocomposite could serve as a novel and promising catalyst in energy and environmental applications.
ABSTRACT
Low-temperature catalysts of mesoporous Co(3)O(4) and Au/Co(3)O(4) with high catalytic activities for the trace ethylene oxidation at 0 degrees C are reported in this paper. The catalysts were prepared by using the nanocasting method, and the mesostructure was replicated from three-dimensional (3D) cubic KIT-6 silicas. High resolution transmission electron microscopy (HRTEM) studies revealed that {110} facets were the exposed active surfaces in the mesoporous Co(3)O(4), whereas the Co(3)O(4) nanosheets prepared by the precipitation method exhibited the most exposed {112} facets. We found that the mesoporous Co(3)O(4) was significantly more active for ethylene oxidation than the Co(3)O(4) nanosheets. The results indicated that the crystal facet {110} of Co(3)O(4) played an essential role in determining its catalytic oxidation performance. The synthesized Au/Co(3)O(4) materials, in which the gold nanoparticles were assembled into the pore walls of the Co(3)O(4) mesoporous support, exhibited stable, highly dispersed, and exposed gold sites. Gold nanoparticles present on Co(3)O(4) readily produced surface-active oxygen species and promoted ethylene oxidation to achieve a 76% conversion at 0 degrees C, which is the highest conversion reported yet.
ABSTRACT
Owing to wide-ranging industrial applications and fundamental importance, tailored synthesis of well-faceted single crystals of anatase TiO(2) with high percentage of reactive facets has attracted much research interest. In this work, high-quality anatase TiO(2) single-crystal nanosheets mainly dominated by {001} facets have been prepared by using a water-2-propanol solvothermal synthetic route. The synergistic functions of 2-propanol and HF on the growth of anatase TiO(2) single-crystal nanosheets were studied by first-principle theoretical calculations, revealing that the addition of 2-propanol can strengthen the stabilization effect associated with fluorine adsorption over (001) surface and thus stimulate its preferred growth. By measuring the (*)OH species with terephthalic acid scavenger, the as-prepared anatase TiO(2) single-crystal nanosheets having 64% {001} facets show superior photoreactivity (more than 5 times), compared to P25 as a benchmarking material.
