Effect of Calcination Temperature on the Structure of a Pt/TiO₂ (B) Nanofiber and Its Photocatalytic Activity in Generating H₂

Abstract

Hydrogen trititanate (H 2Ti 3O 7) nanofibers were prepared by a hydrothermal method in 10 M NaOH at 403 K, followed by acidic rinsing and drying at 383 K. Calcining H 2Ti 3O 7 nanofibers at 573 K led to the formation of TiO 2 (B) nanofibers. Calcination at 673 K improved the crystallinity of the TiO 2 (B) nanofibers and did not cause any change in the morphology and dimensions of the nanofibers. TiO 2 (B) and H 2Ti 3O 7 nanofibers are 10-20 nm in diameter and several micrometers long, but FE-SEM reveals that several of these nanofibers tend to bind tightly to each other, forming a fiber bundle. Calcination at 773 K transformed TiO 2 (B) nanofibers into a TiO 2 (B)/anatase bicrystalline mixture with their fibrous morphology remaining intact. Upon increasing the calcination temperature to 873 K, most of the TiO 2 (B) nanofibers were converted into anatase nanofibers and small anatase particles with smoother surfaces. In the photocatalytic dehydrogenation of neat ethanol, 1% Pt/TiO 2 (B) nanofiber calcined at 673 K was the most active catalyst and generated about the same amount of H 2 as did 1% Pt/P-25. TPR indicated that the calcination of 1% Pt/TiO 2 (B) nanofiber at 573 K produced a poor Pt dispersion and poor activity. Calcination at a temperature higher than 773 K (in ambient air) resulted in an SMSI effect similar to that observed over TiO 2 in the reductive atmosphere. As suggested by XPS, such an SMSI effect decreased the surface concentration of Pt metal and created Pt (delta) sites, preventing Pt particles from functioning as a Schottky barrier and leading to a lower activity. Because of the synergetic effect between TiO 2 (B) and anatase phases, the bicrystalline mixture, produced by calcining at 773 K, was able to counter negative effects such as the reduction in surface area and the SMSI effect and maintained its photocatalytic activity.

Co-Assembly of Nanoparticles in Evaporating Aerosol Droplets: Preparation of Nanoporous Pt/TiO2Composite Particles

“…Activated carbon, carbon nanotubes (CNTs), carbon nanosheets, and silica (SiO 2 ) gel have often been employed as supports for Pt nanoparticles in catalytic applications (Kim et al 2006;Merlo et al 2008;Li et al 2009;Miyatake et al 2009;Yoo et al 2009;Hsu et al 2010;Winjobi et al 2010). TiO 2 nanoparticles have also been used as a support material to enhance the catalytic activity of Pt (Lin et al 2008;Sarkar et al 2008;Chen and Pan 2009;Guo et al 2009;Shanmugam and Gedanken 2009b;Wen et al 2009). In most previous studies, the preparation of Pt/TiO 2 composite involved synthesizing Pt on the surface of TiO 2 .…”

Long-Term Photoelectrochemical Cathodic Protection by Co(OH)2-Modified TiO2on 304 Stainless Steel in Marine Environment

“…32 Loading catalyst promoter is becoming a new attractive way to improve the photocatalytic activity of photocatalysts themselves, and it doesn't change the position of energy bands. [33][34][35][36][37][38][39][40][41][42] However, most of the promoters are noble metals that can't be used widely. So the application of low-cost catalyst promoters like Co(OH) 2 becomes necessary.…”

Photocatalytic activity of nitrogen-doped TiO2-based nanowires: a photo-assisted Kelvin probe force microscopy study

“…the 1-dimensional titanates may be converted to self-similar TiO 2 -based nanowires (Horvath et al 2007;Bamwenda et al 1995;Wu et al 2011aWu et al , 2012. The titanate-to-titania conversion process is robust as it only requires process steps easily scalable and industrially applicable such as ion-exchange, calcination, doping, and surface decoration (Buso et al 2007;Feist and Davies 1992;Lin et al 2008;Qi et al 2011;Wu et al 2011aWu et al , 2012.…”