Tuning the bandgap in Co-doped Mg(OH)₂ nanoparticles

Abstract

Cobalt (Co) doped magnesium hydroxide Mg(OH)2 nanoparticles are synthesized by a surfactant-free co-participation method. Scanning electron microscopy (SEM) images show nanometer size Mg(OH)2 particles in spherically shaped particle-like morphology. Synthesis of these Mg(OH)2 nanocrystals involves the formation of monomeric MgOH[Formula: see text] ions as the precursor for the Mg(OH)2 nuclei which finally evolves in spherical particle-like morphology. X-ray diffraction (XRD) confirms the hexagonal crystal structure of the samples. With increasing Co concentration, the absorption spectra of the samples show narrowing of the bandgap from 5.47 eV (for pure Mg(OH2)) to 5.26 eV (for 10% Co-doped Mg(OH2)) effect is attributed to changes in the interaction potentials between Co and the host Mg(OH)2 lattice due to dopant-induced lattice distortion and the presence of a mixed valance Co[Formula: see text]/Co[Formula: see text] state.

Fabrication of Transparent Mg(OH)2 Thin Films by Drop-Dry Deposition

“…Many fabrication methods of Mg(OH) 2 have been reported, including the hydrothermal synthesis method [16], chemical precipitation method [17][18][19][20][21][22][23], sol-gel technique [24], microwave-assisted synthesis [25], surfactant-mediated growth method [26], electrochemical deposition (ECD) method [27,28], etc. It was reported that Cu-doped Mg(OH) 2 fabricated by ECD is semiconducting [29].…”

Engineering Electronic Structure and Band Alignment of 2D Mg(OH)2 via Anion Doping for Photocatalytic Applications

“…Subsequently, a p-n homojunction is fabricated using Cu-doped Mg(OH) 2 [26]. Cobalt doping is examined to tune the bandgap of Mg(OH) 2 , and 10% Co-doping slightly narrows the band gap from 5.47 eV of pure Mg(OH) 2 to 5.26 eV [19]. Doping of Na, K, Cu, Ag, F, Cl, and C at interlayer sites, and K, Ca, Mn, Fe, Co, Ni, Cu, Zn, Al, Si, Sn, and C at substitutional sites were evaluated to give Mg(OH) 2 n-type or p-type conductivity [27].…”

“…In addition, Mg(OH) 2 has been considered as a photocatalyst for degradation of organic dyes in wastewaters, such as Rhodamine B [ 13 ], and methyl orange [ 14 ], and for CO 2 conversion to solar fuels such as CO, CH 4 , CH 3 OH, HCOOH, and HCOH [ 15 , 16 ]. Owing to different deposition and processing methods as well as characterization tools, Mg(OH) 2 reports a scattered experimental band gap values from 5.17 eV [ 17 , 18 ], 5.47 eV [ 19 ], 5.70 eV [ 17 ], to 7.60 eV [ 20 ], and is considered a wide gap insulator. Accordingly, it is used as a buffer layer in heterostructure solar cells [ 18 , 21 ] and to suppress recombination of photogenerated electrons in dye-sensitized solar cells [ 22 , 23 ].…”