Mono- and bimetallic nanoparticles decorated KTaO <inf>3</inf> photocatalysts with improved Vis and UV–Vis light activity
Abstract:
Novel mono- and bimetallic nanoparticles (MNPs and BNPs) decorated surface of perovskite-type KTaO 3 photocatalysts were successfully synthesized by hydrothermal reaction of KTaO 3 followed by photodeposition of MNPs/BNPs. The effect of noble metal type (MNPs = Au, Ag, Pt, Pd, Rh, Ru or BNPs = Au/Pt, Ag/Pd, Rh/Ru), amount of metal precursor (0.5, 1.0, 1.5 or 2.0 wt%) as well as photoreduction method (simultaneous (both) or subsequent (seq) deposition of two metals) on the physicochemical and photocatalytic properties of MNPs- and BNPs-KTaO 3 have been investigated. All as-prepared photocatalysts were subsequently characterized by UV–Vis diffuse reflectance spectroscopy (DRS), Brunauer-Emmett-Teller (BET) specific surface area and pore size distribution measurement, scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDS), powder X-ray diffraction (PXRD), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS) and photoluminescence (PL) emission spectroscopy. The crystal structure was performed using visualization for electronic and structural analysis (VESTA). The photocatalytic activity under Vis light irradiation was estimated in phenol degradation in aqueous phase and toluene removal in gas phase, while under UV–Vis light irradiation was measured amount of H 2 generation from formic acid solution. The absorption properties of O 2 and H 2 O molecules on KTaO 3 (1 0 0) surface supported by Au or Au/Pt NPs was also investigated using density-functional theory (DFT). The experimental results show that, both MNPs-KTaO 3 and BNPs-KTaO 3 exhibit greatly enhanced pollutant decomposition efficiency under Vis light irradiation and highly improved H 2 production under UV–Vis light irradiation compared with pristine KTaO 3 . MNPs deposition on KTaO 3 surface effects by disperse metal particle size ranging from 11 nm (Ru NPs) to 112 nm (Au NPs). Simultaneous addition of Au/Pt precursors results in formation of agglomerated larger metal nanoparticles (50–100 nm) on KTaO 3 surface than subsequent deposition of Au/Pt with composition of concentrated smaller metal nanoparticles (>50 nm) on KTaO 3 surface. The 0.5 Au/1.5 Pt-KTaO 3 _both and 2.0 Rh-KTaO 3 reveal the highest Vis-induced activity among prepared samples in aqueous phase (14.75% of phenol decomposition after 90 min of irradiation) and gas phase (41.98% of toluene removal after 60 min of irradiation), respectively. The theoretical calculations confirmed that adsorption energy of O 2 and H 2 O molecules was increased after loading of Au or Au/Pt NPs on KTaO 3 (1 0 0) surface. Control tests with scavengers show that O 2[rad]− radical is significantly involved in phenol oxidation under Vis light irradiation, which proposed mechanism is based on direct electron transfer from MNPs/BNPs to conduction band of KTaO 3 . The highest amount of H 2 evaluation is obtained also by 0.5 Au/1.5 Pt-KTaO 3 _both after 240 min of UV–Vis light irradiation (76.53 µmol/min), which is eleven times higher than for pristine KTaO 3 (6.69 µmol/min). Moreover, the most photocatalytic samples for each model reaction present good repeatability and stability after subsequent three cycles. Summarized, MNPs- and BNPs-KTaO 3 are promising material in advanced applications of photocatalysis.
Año de publicación:
2018
Keywords:
- Perovskite KTaO 3
- Vis/UV–Vis photocatalytic activity
- Mono- and bimetallic nanoparticles
- Noble metal photodeposition
- Pollutant degradation/H generation 2
Fuente:
Tipo de documento:
Article
Estado:
Acceso restringido
Áreas de conocimiento:
- Nanopartícula
- Nanopartícula
- Fotovoltaica
Áreas temáticas:
- Química física
- Química inorgánica
- Ingeniería y operaciones afines