Reducing the Energy Band Gap of Cobalt Hydroxide Nanosheets with Silver Atoms and Enhancing Their Electrical Conductivity with Silver Nanoparticles.
Montakan SuksomboonKetsuda KongsawatvoragulSalatan DuangdangchoteMontree SawangphrukPublished in: ACS omega (2021)
Although cobalt hydroxide (Co(OH)2) has been attracting attention in several applications, its photoelectrochemical property has not yet been fully investigated. In this work, tuning the energy band gap of Co(OH)2 nanosheets with silver atoms and enhancing their electrical conductivity with silver nanoparticles were then focused. A Ag-doped α-Co(OH)2 thin film was successfully synthesized via an electrodeposition method. The optical properties of the as-prepared materials were characterized by UV-vis and fluorescence lifetime spectroscopies and further confirmed by density functional theoretical calculation. It was found that Ag atoms between adjacent layers of Co(OH)2 can reduce its electronic band gap to 2.45 eV (α-Co(OH)2) as compared to 2.85 eV of β-Co(OH)2. In terms of electrochemical properties, silver nanoparticles (AgNPs) can enhance the electrical conductivity of Co(OH)2 nanosheets, leading to faster charge transfer reducing the internal resistance and significantly increasing the overall charge storage performance. Interestingly, under light illumination, Ag-doped α-Co(OH)2 exhibits ca. 0.8 times lower charge storage capacity as compared to that under the dark condition. This is because the photoelectrons can be recombined with the generated holes in the conduction band. The charge storage mechanisms of Ag-doped α-Co(OH)2 operated under dark conditions and light irradiation were further studied and confirmed using in situ electrochemical X-ray absorption spectroscopy (XAS). Overall, the in situ XAS supports the electrochemical result. This finding may pave a way to further develop photoactive advanced functional materials of metal hydroxides and oxides.
Keyphrases
- silver nanoparticles
- quantum dots
- visible light
- reduced graphene oxide
- gold nanoparticles
- sensitive detection
- highly efficient
- energy transfer
- solar cells
- ionic liquid
- molecularly imprinted
- metal organic framework
- label free
- high resolution
- single molecule
- working memory
- radiation therapy
- computed tomography
- atomic force microscopy
- mass spectrometry
- protein kinase
- tandem mass spectrometry