The selective deposition of silver nanoparticles onto {101} facets of TiO2 nanocrystals with co-exposed {001}/{101} facets, and their enhanced photocatalytic reduction of aqueous nitrate under simulated solar illumination

Highly efficient photocatalytic reduction of environmental pollutants requires the enrichment of photogenerated electrons on the photocatalyst's surface. Thus, proper material design and modification are needed to efficiently separate photogenerated electron/hole pairs and achieve their oriented migrations for the enrichment of photogenerated electrons on their surface. In this work, a modified photo-deposition process was developed which successfully deposited silver nanoparticles selectively on {1 0 1} facets of TiO2 nanocrystals with co-exposed {0 0 1}/{1 0 1} facets. The synergistic effect of crystal facet engineering and the selective deposition of silver nanoparticles on {1 0 1} facets largely enhanced the separation of photogenerated carriers and enriched the presence of photo-generated electrons onto the surface of TiO2 to a net negative-charged surface. A strong photocatalytic reduction capability of the sample was demonstrated by its superior photocatalytic reduction activity on aqueous nitrate under a simulated solar illumination. The removal ratio of aqueous nitrate reached similar to 95%, and most of the reduction product was the desirable N-2 with the selectivity over 90%. These TiO2 nanocrystal with co-exposed {0 0 1}/{1 0 1} facets and silver modification on {1 0 1} facets could also effectively remove both nitrate and various organic pollutants from water simultaneously. (C) 2015 Elsevier B.V. All rights reserved.