In Tandem Control of La-Doping and CuO-Heterojunction on SrTiO(3) Perovskite by Double-Nozzle Flame Spray Pyrolysis: Selective H(2) vs. CH(4) Photocatalytic Production from H(2)O/CH(3)OH

ABO(3) perovskites offer versatile photoactive nano-templates that can be optimized towards specific technologies, either by means of doping or via heterojunction engineering. SrTiO(3) 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 SrTiO(3) nanoparticles with controlled La-doping in tandem with SrTiO(3)/CuO-heterojunction formation. So-produced La:SrTiO(3)/CuO nanocatalysts were optimized for photocatalysis of H(2)O/CH(3)OH 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:SrTiO(3) material achieved maximal efficient photocatalytic H(2) production, i.e., 12 mmol g(−1) h(−1). Introduction of CuO on La:SrTiO(3) enhanced selective production of methane CH(4). The optimized 0.25La:SrTiO(3)/0.5%CuO catalyst achieved photocatalytic CH(4) 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 SrTiO(3) lattice regarding the H(2)-production, plus the effect of interfacial CuO on the promotion of CH(4) 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:SrTiO(3)/CuO with a diligent control of doping and heterojunction in a single-step synthesis.