Tailored synthesis of macroporous Pt/WO₃ photocatalyst with nanoaggregates via flame assisted spray pyrolysis

Abstract

in Wiley Online Library (wileyonlinelibrary.com)High-surface-area macroporous WO 3 particles with deposited Pt (Pt/WO 3 ) were successfully synthesized for the first time, using flame-assisted spray pyrolysis. Nanoparticle aggregates-like structures (nanoaggregates) were formed, although a salt precursor was used for the synthesis. The macroporous structure was tailored by changing the mass ratio of the polystyrene template to ammonium tungstate pentahydrate. The cavities between the nanoaggregates formed mesopores, which increased the surface area. The presence of meso-and macro-pores in the synthesized Pt/WO 3 particles improved their photocatalytic activities in visible-light-induced photodegradation of rhodamine B. The combination of a high surface area and the presence of an in situ-deposited Pt cocatalyst gave a high photodecomposition rate, approximately 9.6 times higher than that achieved with dense WO 3 particles. This research provides a promising strategy for synthesizing submicron particles with high surface areas at a high production rate, and is suitable for industrial applications.

Correlations between Reduction Degree and Catalytic Properties of WOx Nanoparticles

“…This meant that the electron–hole pairs tended to recombine rapidly. 36 This was evident from the results where the decomposition rates of RhB under visible light irradiation were lower than those in dark conditions.…”

Aerosol Spray Controlled Synthesis of Nanocatalyst using Differential Mobility Analysis Coupled to Fourier-Transform Infrared Spectroscopy

“…Aerosol spray-based processing, which combines the production of spray droplets of liquid precursors and the subsequent pyrolysis of the produced spray, has been shown as a promising synthetic route for obtaining functional nanoparticles from an industrial perspective. ,− ,,,, In principle, the solvent in the sprayed liquid droplets evaporates via an aerosol-phase drying process. Followed by the procedure of thermal decomposition, the dried precursor particles transform to solid nanoparticles. ,,,− , The attractive technical features of the aerosol-based processing include that it is a continuous, low-cost process with a short reaction time, showing potential for a large-scale tailored production. ,,− A variety of aerosol spray generation routes in combination with spray pyrolysis have been employed to date, for example, nebulization, ultrasonication, and aerosol flame synthesis, ,− by which high-quality multicomponent nanoparticles with controlled size and composition are able to be produced via the gas-phase evaporation-induced self-assembly. ,− ,− ,,, …”

Tubular Flame Combustion for Nanoparticle Production

“…Among various bottom-up processes, aerosol processes involve syntheses where the main reactions occur in the gas phase. , Such processes are often applied on an industrial scale. Flame (assisted) spray pyrolysis [F­(A)­SP] is a widely used aerosol process for producing single- and multicomponent nanoparticles with high purity in a single step , based on various types of flame systems, such as a Bunsen flame, , coflow diffusion flame, − spray flame, , and flat flame. , Although the flame types commonly used for F­(A)­SP are available with inexpensive and simple set ups, the energy efficiency of combustion should also be considered. Owing to the structure of these flames, energy is lost from the system, for example, in the form of radiation.…”

“…Although adiabatic flame temperature of this combustion system could attain around 3000 K, nanometer-sized particles could not be produced. It indicates large heat losses behind the flame . Hence, the tubular flame combustion has a potential to enable nanoparticle production with high yield and higher energy efficiency.…”