Promoted hexavalent chromium ion photoreduction over visible-light active RuO2/TiO2 heterojunctions prepared by solution process

Abstract

The accretion of heavy metal ions, especially chromium hexavalent ions (Cr (VI)), in the environment introduce severe impacts on humankind. This study presents a triblock copolymer-assisted sol–gel synthesis of mesoporous TiO2, which is subsequently coupled with RuO2 nanoparticles at 1.0 ∼ 4.0 wt% by thermal annealing. The RuO2 nanoparticles of 6.0 nm size on average were uniformly dispersed on the 83.7 nm mesostructured anatase TiO2 phase nanoparticles as confirmed by XRD and TEM investigations. Regardless of the minor amount of RuO2, the visible-light harvesting of TiO2 as a result of a bandgap decrease of 0.66 eV was revealed. The prepared RuO2/TiO2 were employed for the visible-light-driven photocatalytic reduction of Cr (VI). The 3.0 wt% impregnated RuO2/TiO2 achieved the highest photocatalytic Cr(VI) reduction at 117.41 µmol min−1, which increased to 171 µmol min−1 through optimizing its dose at 2.0 gL−1 with magnificent stability. and photocurrent responses, the promoted photocatalytic activity was referred to as superior charge separation by quasi metallic RuO2 by photoluminescence and photocurrent measurements. This RuO2/TiO2 will open a new avenue for the visible-light elimination of heavy metals from industrial wastewater in the future.