Nanoarchitectonics of CuNi bimetallic nanoparticles in ionic liquids for LED-assisted synergistic CO2 photoreduction
Abstract
An efficient and robust photocatalysts have been developed by combining bimetallic CuNi nanoparticles and TiO2. Simple co-reduction of CuCl2.2H2O and NiCl2.6H2O in 1-n-butyl-methylimidazolium tetrafluoroborate (BMIm.BF4) ionic liquid affords small sized (4-5 nm) bimetallic CuNi NPs.
Low-Energy Ion Scattering (LEIS) and magnetic measurements analyses reveals that the NPs are alloyed nanostructure-having Ni enriched surface. CuNi NPs decorated on P25-TiO2 remarkably promote the generation of CH3OH and syngas as compared to their monometallic counter-parts using 1200 mW LEDs of 450 nm (visible) light irradiations in an optofluidic microreactor.
The system continuously produces CH3OH with a rate of 102.1 mu m.g- 1.h-1 (AQY 0.90%) and syngas (H2 118.8 and CO 24.6 mu mol.g- 1.h-1), represents a high yield and quantum efficiency. Where as, its counter-part, Ni/TiO2, generate CH3OH with a rate of 37.0 mu m.g- 1.h-1, H2 200.0 mu mol.g- 1.h-1 and CO 15.1 mu mol.g- 1.h-1 having 0.33, 0.59 and 0.1% AQY, respectively.
The presence of Cu in CuNi NPs significantly boosts the catalytic performance via metal dilution and synergistic effect, causes the red shift and increases the con-ductivity, while Ni increases the band gap, thereby achieving a record high CH3OH rate generation.