Abstract

Designing nanomaterials with dual photo-chemical and -thermal capabilities in oxidative catalysis creates opportunities for the improved degradation of water pollutants. The precise design of dual-photo/thermo nanocatalysts remains a challenge, since both the size and the active facets of the nano-crystals exposed to the media have a paramount impact on their performance to produce hot carriers and reactive oxygen species (ROS). This study investigates on morphological tailoring of SnO2 nanomaterials to modulate their electronic structure conferring them autarchic and synergic photo-thermal catalytic functions able to fasten the oxidation of trivalent to pentavalent arsenic in water. The fine control of the structural dimensionality of SnO2 nanomaterials (i.e. with controlled-morphologies including nanoparticles, nanorods, nanosheets, and nanoflowers) allowed modulating their electronic properties and band structure while inducing structural defects able to produce hot carriers. SnO2 nano-catalysts exhibit high efficiency in the photocatalytic oxidation of As(III) into As(V). Under irradiation, the photothermal effect fastens the catalysis kinetics by increasing the temperature of the aqueous medium up to 5.2 degrees C. In parallel, the temperature gradient enhanced the charge carrier transfer arising from photocatalysis, boosting the ROS generation. All in all, the dual effect gives rise to accelerated As(III) to As(V) photo-oxidation rates that have been explained in detail from a mechanistic perspective.