Abstract
This study outlines the impact of Co doping on the structures, morphologies, optical, and photochemical activities of nanoporous CdS films for efficient solar energy conversion. A sequence of nanotextured films of cadmium cobalt sulfide (Cd
1 −
x
Co
x
S; where
x
= 0, 0.02, 0.04, 0.06, and 0.08) were grown on glass substrates using spray pyrolysis method followed by annealing at 300 °C for 2 h. The grown Cd
1
−
x
Co
x
S films are of single wurtzite phase and polycrystalline nature. The preferential crystallographic growth of Cd
1 −
x
Co
x
S nanocrystallites along the (002) is changed to (101) direction for
x
≥ 0.06. The crystallite size and lattice parameters are decreased for
x
≤ 0.04. Also, the absorption is increased and the optical bandgap is decreased to 2.40 eV at 6% Co-doping. The morphological study reveals the growth of agglomerated pure CdS nanorods. The incorporation of Co increases the density of nanorods, which self-assembled to form nanoporous surface at 2 and 4%. A random distribution of irregular nanorods accompanied by patterned spherical clusters is observed at 6%, which is assembled to a nanoporous pattern at 8%. The photocatalytic performances and reaction kinetics of the films are investigated for methylene blue dye decomposition under sunlight and artificial light illumination. The 6% Co-doped film reached the complete removal after 240 min under sunlight irradiation. This film showed higher stability than pure CdS film for 7 runs. Therefore, the combination of spray pyrolysis and adjustable doping level is a viable way for producing large-scale and reusable photocatalytic films for eco-friendly removal of dyes from industrial wastewater.
Highlights
Cd
1 − x
Co
x
S nanofilms of different doping levels (0 ≤
x
≤ 8%) have been designed.
Morphological, structural, and optical properties of Cd
1 −
x
Co
x
S films were studied.
The photocatalytic performance and stability of Cd
1 −
x
Co
x
S films were investigated
Cd
0.94
Co
0.06
S film is the most suitable film for MB dye degradation under sunlight.
Reaction kinetics and reusability are studied under sunlight and artificial light.