Hole and Electron Doping Outcomes in Bi₂YO₄Cl

The outcomes of hole and electron dopingin Bi2YO4Cl by introducing Ca2+ andZr(4+) for Y3+ is examined. Holes induced oxidationof Bi3+ (10%) to Bi5+, causing a blueshift ofthe absorptionedge. Bi3+/Bi5+ oxidized As(III) to As(V) ina heterogeneous fashion. Electron doping caused the reduction of Bi(III)(14%) to Bi(0), accompanied by a decrease in the optical band gap.Through DFT calculations, the electronic and optical properties ofdoped systems are rationalized. Recognizingthe deficiency in the hole and electron doping outcomesin layered bismuth-based oxyhalides intergrowths, the current studywas addressed to the doping of Ca2+ and Zr4+ for Y3+ in Bi2YO4Cl. The sampleswere rapidly synthesized by a sol-gel auto combustion methodand characterized extensively. Up to 30 mol % Y could be substitutedwith Ca in tetragonal symmetry and without the appearance of any additionalphase. The unit cell parameters varied nonlinearly with the elongationof the Y-O bond. The Raman spectra supported the local sitedistortion. The calcium-substituted samples displayed selected areaelectron diffraction characteristics similar to those of Bi2YO4Cl. A blueshift of the absorption edge was noticedwith increasing calcium content yielding optical band gap values inthe 2.40-2.57 eV range. The creation of 10% Bi5+ in Bi(2)Y(0.70)Ca(0.30)O(4)Clwas established with the help of XPS measurements and redox titrations.The higher reactivity of Bi5+ in an aqueous solution hasbeen demonstrated for the oxidation of As(III) to As(V). Electrondoping through Zr4+ incorporation was possible up to 30mol % in Bi2YO4Cl. The Y-O bonds arecontracted, and the Bi-O bonds are elongated with increasingZr(4+) content. Zr4+'s incorporation induceda local distortion. The color of the sample changed from bright yellowto deep yellow with Zr inclusion, resulting in a progressive decreasein optical band gap values. The introduction of electrons caused thereduction of 13.6% of Bi(III) to Bi(0). These results have establishedthe vulnerability of Bi2O2 chains to chargecarriers in Bi2YO4Cl. Density functional theory(DFT) calculations were implemented to understand the electronic andoptical properties of the pristine and doped compounds. From the bandstructure calculations, the chosen compounds were found to be indirectband gap semiconductors. The results of the DFT calculations werein good agreement with the experiment; however, for the doped cases,virtual crystal approximation has been used considering uniform dopingat the Y-site.