In Tandem Control of La-Doping and CuO-Heterojunction on SrTiO3 Perovskite by Double-Nozzle Flame Spray Pyrolysis: Selective H2 vs. CH4 Photocatalytic Production from H2O/CH3OH

Abstract

ABO3 perovskites offer versatile photoactive nano-templates that can be optimized towards specific technologies, either by means of doping or via heterojunction engineering. SrTiO3 is a well-studied perovskite photocatalyst, with a highly reducing conduction-band edge. Herein we present a Double-Nozzle Flame Spray Pyrolysis (DN-FSP) technology for the synthesis of high crystallinity SrTiO3 nanoparticles with controlled La-doping in tandem with SrTiO3/CuO-heterojunction formation. So-produced La:SrTiO3/CuO nanocatalysts were optimized for photocatalysis of H2O/CH3OH mixtures by varying the La-doping level in the range from 0.25 to 0.9%. We find that, in absence of CuO, the 0.9La:SrTiO3 material achieved maximal efficient photocatalytic H2 production, i.e., 12 mmol g−1 h−1. Introduction of CuO on La:SrTiO3 enhanced selective production of methane CH4. The optimized 0.25La:SrTiO3/0.5%CuO catalyst achieved photocatalytic CH4 production of 1.5 mmol g−1 h−1. Based on XRD, XRF, XPS, BET, and UV-Vis/DRS data, we discuss the photophysical basis of these trends and attribute them to the effect of La atoms in the SrTiO3 lattice regarding the H2-production, plus the effect of interfacial CuO on the promotion of CH4 production. Technology-wise this work is among the first to exemplify the potential of DN-FSP for scalable production of complex nanomaterials such as La:SrTiO3/CuO with a diligent control of doping and heterojunction in a single-step synthesis.

Flame Spray Pyrolysis Synthesis of Vo-Rich Nano-SrTiO3-x

“…We underline that these size distributions are a result of at least 100 particles and were obtained from several TEM images. These results are in good agreement with the structural characterization results of FSP-made SrTiO 3 particles from our previous work [ 25 ]. Comparison of d XRD and d TEM reveals a well-known effect in which larger particles dominate the diffraction patterns, while the contribution of smaller particles is less visible.…”

“…Previously, Yuan et al presented FSP-made SrTiO 3 with dopings of Co, Fe, Mn, Ni and Cu [ 23 , 24 ]. Our previous work showcased La-doping and CuO-heterojunction on SrTiO 3 enhancement and selective H 2 vs. CH 4 photocatalytic production from H 2 O/CH 3 OH [ 25 ].…”

Industrial-Scale Engineering of Nano {RuO2/TiO2} for Photocatalytic Water Splitting: The Distinct Role of {(Rutile)TiO2–(Rutile)RuO2} Interfacing

“…In the DN-FSP configuration, TiO 2 and RuO 2 nanoparticles were formed separately using two FSP nozzles, code-named Nozzle-1 and Nozzle-2, respectively (refer to Figure D). After a series of optimizations, ,, an asymmetrical DN-FSP setup was employed (see Figure B,D), where the two nozzles were arranged at specific intersection distances and angles. Specifically, Nozzle-2, dedicated to the synthesis of RuO 2 , was positioned at an angle of β = 30° and a distance of 64 cm from the particle-collection glass-fiber filter.…”

Advanced Flame Spray Pyrolysis (FSP) Technologies for Engineering Multifunctional Nanostructures and Nanodevices

“…The dopant concentration significantly controlled the selective production of H2 or CH4 from H2O/CH3OH. CuO incorporation drastically shifted production to CH4, achieving a rate of 1.5 mmol g −1 h −1 for the La:SrTiO3/CuO catalyst (0.5 wt%) [58]. TiO 2 : Grossmann et al, through the utilization of DN-FSP, produced TiO 2 with deposited Pt particles [67].…”