A Family of Visible‐Light Responsive Photocatalysts Obtained by Dispersing CrO₆ Octahedra into a Hydrotalcite Matrix

Abstract

Visibly clear: A family of visible‐light‐responsive MCr–layered double hydroxides (LDHs; M=Cu, Ni, Zn) were synthesized. These show remarkable photocatalytic activity with visible‐light irradiation. Experimental and computational studies revealed that the visible‐light response of MCrNO3–LDHs originates from a d–d transition in the orderly dispersed CrO6 octahedra in the hydrotalcite layer.

Layered Double Hydroxide Nanostructured Photocatalysts for Renewable Energy Production

“…Zhao and co-workers used DFT calculations to probe the electronic structure of CuCr-LDH photocatalysts. [ 44,45 ] Figure 6 shows the band structure calculated for CuCr-LDH, which reveals a band gap of about 1.6 eV, with the compound behaving as a direct band gap semiconductor that allows easy electron-hole separation under visible light. In addition, the DOS results show that the valence band (VB) maximum is dominated by occupied Cr 3d orbitals (A 2g ), and the conduction band (CB) minimum consists of unoccupied Cr 3d orbitals (T 2g + T 1g ).…”

“…Right panel reproduced with permission. [ 44 ] Figure 11. Diffuse refl ectance UV-Vis spectra (A), and PL spectra (B) of self-assembled ZnCr-LDH/GO and ZnCr-LDH.…”

Layered Double Hydroxide Materials in Photocatalysis

“…Various Zn/Cr atomic ratios (from 4:2 to 4:0.25) were tested for the visiblelight photocatalytic oxygen generation, and the results showed that the efficiency of photocatalysts enhances asymptotically with the increase of Cr content [28]. Wei et al [29] further reported the synthesis of visible-light-responsive MCr-X-LDHs (M ¼ Cu, Ni, Zn; X ¼ NO 3 À , CO 3 2À ) by a simple and scale-up coprecipitation method. It was found that the MCr-NO 3 -LDHs (M ¼ Cu, Ni) exhibit 20 times higher photocatalytic activity than P25, owing to the high dispersion of the CrO 6 unit in the LDH matrix.…”

“…Wei et al [29] proposed that the highly efficient photocatalytic performance of Cr-containing LDHs is attributed to the visible-light response originated from the d-d transition of the CrO 6 octahedron in the LDH layer. Moreover, the abundant OH groups on the surface of LDHs facilitate the generation of highly reactive hydroxyl radicals by reacting with photogenerated holes, which provides enough oxidation active sites for the degradation of pollutants.…”

Ion-exchangeable semiconductor materials for visible light-induced photocatalysis

“…Although these characterization techniques have been widely used to investigate ion-exchangeable materials with visible light absorption feature, theoretical calculation especially density functional theory calculation has demonstrated to be quite powerful in investigating semiconductor materials from fundamental understanding aspects. In fact, theoretical calculations have been successfully used to study many groups of visible light-responsive semiconductor materials, including ion-exchangeable semiconductor materials [6,67,79,85,86,102,104].…”