Revisiting the Key Optical and Electrical Characteristics in Reporting the Photocatalysis of Semiconductors

Abstract

Photocatalysis has been studied and considered as a green and practical approach in addressing environmental pollution. However, factors that affect photocatalytic performance have not been systematically studied. In this work, we have presented a comprehensive roadmap for characterizing, interpreting, and reporting semiconductors’ electrical and optical properties through routinely used techniques such as diffuse reflectance spectroscopy, electrochemical techniques (Mott–Schottky plots), photoluminescence, X-ray photoelectron spectroscopy, and ultraviolet photoelectron spectroscopy in the context of photocatalysis. Having precisely studied the band structure of three representative photocatalysts, we have presented and highlighted the essential information and details, which are critical and beneficial for studies of (1) band alignments, (2) redox potentials, and (3) defects. Further works with a comprehensive understanding of the band structure are desirable and hold great promise.

Defect Engineering of Porous g-C3N4 to Add Multifunctional Groups for Enhanced Production of H2O2 via Piezo-Photocatalysis

“…To determine the photocatalytic mechanism of the materials, a Kubelka–Munk model was explored in this study to compute the bandgap energies. The plots in Figure a were drawn by applying eq , which exhibits the relationship between ( F ( R ) h ν) 1/2 and h ν true( log ( 1 R ) ln ( 10 ) l h v true) r = B ( h v − E g ) where R and E g represent reflectance values and the bandgap energy (eV) of the materials, l and ν are the sample width (cm) and frequency (s –1 ), h and B are Planck’s constant and an equation’s constant, and r is equal to 1/2 for indirect bandgap materials, respectively.…”

Understanding Graphitic Carbon Nitride as Photocatalyst: A Case Study on Thermal Engineering of Physical and Chemical Features

“…1 - R \left.\right)\right)^{2}}{2 R}$, where F ( R ) is the Kubelka–Munk function, which is proportional to the absorption coefficient ( α ) and R is the reflectance of sample. Then by using Tauc equation and extrapolating the linear part of curve to the energy axis ( hν ), the optical bandgap could be determined (Figure 3b), [ 34,35 ] which was found to significantly decrease as a function of the synthesis temperature. The calculated bandgaps are 3.09, 2.93, and 2.38 eV for U400, U500, and U600, respectively.…”

Rapid fabrication of MgO@g-C3N4 heterojunctions for photocatalytic nitric oxide removal

“…In addition, the bandgap energy of materials was calculated by using the Tauc and the Kubelka–Munk equation as described in Equations 5–7 [ 43 ]:…”

“…The photocatalytic NO degradation efficiency (η), the yield of NO 2 conversion (γ), the apparent quantum efficiency (AQE, φ), and the DeNOx index (αDeNOX αDeNOx) were calculated by using Equations 1-4: [41][42][43]:…”