Photo/Electrocatalytic Properties of Nanocrystalline ZnO and La–Doped ZnO: Combined DFT Fundamental Semiconducting Properties and Experimental Study

Abstract

This work reports the synthesis of nanocrystalline ZnO and 5% La‐doped ZnO (La/ZnO) materials for photo/electrocatalytic degradation of Rhodamine B. The samples were characterized by X‐Ray diffraction, scanning and transmission electron microscopy, X‐Ray photoelectron spectroscopy and diffuse reflectance spectra. The effect of La doping on electronic structure was investigated using density functional theory calculations (DFT), La‐doped ZnO showed an n‐type metallic nature compared to pristine ZnO and La doping creates occupied states within the band gap edge. Under UV light, La/ZnO showed higher kinetic constant and efficiency than ZnO. A possible mechanism was elaborated on the basis of DFT and active trapping measurements. Different initial Rhodamine B concentration were studied to assess the electro‐oxidation of RhB. The electrochemical degradation of RhB over La/ZnO spindles electrode was pronounced with three time's high kinetic constant. The superior electro/photoactivity of La/ZnO was due to its unique morphology, high charge separation of the charge carriers and higher conductivity induced by La‐doping (intermediary levels). Superoxide ions and holes were the main active species for the photodegradation. Whereas, synergetic effect of hydroxyl radicals and hypochlorite ions were responsible of the high RhB electrocatalytic degradation.

Highly Active Sb2S3-Attached Mo–WO3 Composite Film for Enhanced Photoelectrocatalytic Water Splitting at Extremely Low Input Light Energy

“…To further investigate the effect of Mo on WO 3 , DFT calculations were conducted. The calculated direct band gaps of WO 3 , 3% Mo–WO 3 , and 5% Mo–WO 3 were 1.25, 1.21, and 1.17 eV, respectively (Figure a–c), which underestimates the experimental values because of failure to accurately describe the discontinuity in the exchange-related potentials Figure d displayed the partial density of states (PDOS) of catalysts.…”

“…The calculated direct band gaps of WO 3 , 3% Mo−WO 3 , and 5% Mo−WO 3 were 1.25, 1.21, and 1.17 eV, respectively (Figure 12a−c), which underestimates the experimental values because of failure to accurately describe the discontinuity in the exchange-related potentials. 54 Figure 12d displayed the partial density of states (PDOS) of catalysts. Moreover, the PDOS reveals that, for 5% Mo−WO 3 , the top of the VB is dominated by the O 2p states, and the bottom of the CB is dominated by the W 3d and Mo 3d states.…”

Photocatalytic oxidation of pollutants in gas-phase via Ag3PO4-based semiconductor photocatalysts: Recent progress, new trends, and future perspectives

“…Heterogeneous photocatalytic degradation due to numerous facets over conventional treatment strategies is regarded as an effective alternative remediation technology (S. (Ahsaine et al, 2018;Barebita et al, 2020;Bouziani et al, 2020;Erdogan et al, 2019;Naciri et al, 2020b;S. Ferraa et al, 2020;Shaim et al, 2019).…”

Polyaniline coated hematite sand supported on graphene oxide (HS@PANI‐GO) as a new magnetic material for advanced catalytic oxidation based on sulfate radicals: optimization using response surface methodology

“…To overcome these disadvantages, advanced oxidation processes (AOPs) should be preferentially used. Among these AOPs are, photocatalysis, [10][11][12] electrocatalysis, 13 photo-electrocatalysis, 14 electro-Fenton, [15][16][17][18] Fenton, 19,20 peroxicoagulation, 21,22 photo-Fenton, 23 sono-Fenton, 24 sonochemical methods, 25 hydrodynamic cavitation, 26 zero valent metals based AOPs, 27,28 and oxidation processes based on the use of radicals (SO 4 −• , OH • ). 29,30 However, the oxidation by the radicals…”

“…To overcome these disadvantages, advanced oxidation processes (AOPs) should be preferentially used. Among these AOPs are, photocatalysis, electrocatalysis, photo‐electrocatalysis, electro‐Fenton, Fenton, peroxicoagulation, photo‐Fenton, sono‐Fenton, sonochemical methods, hydrodynamic cavitation, zero valent metals based AOPs, and oxidation processes based on the use of radicals (SO 4 −• , OH • ) . However, the oxidation by the radicals of sulfate SO 4 −• attracted a lot of attention because of the high oxidation potential that is expected at 2.01 V compared to others radicals .…”