Correction: Influence of Cu doping on the visible-light-induced photocatalytic activity of InVO₄

Abstract

Correction for ‘Influence of Cu doping on the visible-light-induced photocatalytic activity of InVO₄’ by Natda Wetchakun et al., RSC Adv., 2017, 7, 13911–13918, DOI: 10.1039/C6RA27138C.

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The authors regret errors in Fig. 4, 7, and 9 in the previously published article. The corrections for the errors in the article are described as follows:

(1) The diffuse reflectance spectra of pure InVO₄ and 1.0 mol% Cu-doped InVO₄ are shown in Fig. 4. The absorption margin of 1.0 mol% Cu-doped InVO₄ was shifted to a longer wavelength, indicating a decrease in the band gap with respect to pure InVO₄. The absorption margins of the pure InVO₄ and 1.0 mol% Cu-doped InVO₄ samples were 505 nm and 510 nm, corresponding to band gaps of 2.51 eV and 2.45 eV, respectively (Fig. 4a and b).

Fig. 4 Kubelka–Munk absorbance spectra and band gaps (insets) of the pure InVO₄ (a) and 1.0 mol% Cu-doped InVO₄ (b) samples.

(2) The band edge positions of the conduction band (CB) and the valence band (VB) of InVO₄ can be calculated by the following equation: E⁰_CB = χ − E^C − 0.5E_g,¹ where χ is the electronegativity of the semiconductor, E^C is the energy of free electrons on the hydrogen scale of 4.5 eV, E_g is the band gap of InVO₄, and the χ value of InVO₄ is 5.74 eV.² The E_g value of InVO₄ evaluated from the UV-vis DRS analysis was about 2.51 eV. The valence band energy (E_VB) can be calculated by the following equation:³ E_VB = E_CB + E_g, where E_CB is the conduction band energy. Based on the equation above, the calculated CB and VB edge potentials of InVO₄ were −0.02 eV and 2.49 eV, respectively. Now, we are in a position to discuss the photocatalytic mechanism of Cu-doped InVO₄ for MB degradation (Fig. 7). In the photocatalysis process, when the absorbed photon energy (hν) equals or exceeds the band gap, the Cu-doped InVO₄ generates electron–hole (e⁻/h⁺) pairs. In that case, the generated electrons from the valence band can be transferred to the conduction band of InVO₄. Since the CB edge potential of InVO₄ (−0.02 eV) is higher than the standard redox potential, E⁰(O₂/O₂˙⁻) = −0.33 V vs. NHE at pH 7, this suggests that the electrons in the CB of InVO₄ cannot reduce O₂ to the superoxide radical ion (O₂˙⁻). In addition, the VB of InVO₄ (2.49 eV) is higher than the standard redox potential, E⁰(OH⁻/OH˙) = 1.99 V vs. NHE at pH 7. This indicates that the photogenerated holes in the valence band of InVO₄ can oxidize the hydroxyl ion (OH⁻) or water (H₂O) to form the hydroxyl radical (OH˙).

Fig. 7 Schematic of the charge migration and separation on Cu-doped InVO₄.

(3) Due to the contradiction between the scavenging test and the proposed photocatalytic mechanism, Fig. 9 was removed from the original article.

The Royal Society of Chemistry apologises for these errors and any consequent inconvenience to authors and readers.

References

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