Layered Double Hydroxides as Highly Efficient Photocatalysts for Visible Light Oxygen Generation from Water

Abstract

Oxygen generation through photocatalytic water splitting under visible light irradiation is a challenging process. In this work we have synthesized a series of Zn/Ti, Zn/Ce, and Zn/Cr layered double hydroxides (LDH) at different Zn/metal atomic ratio (from 4:2 to 4:0.25) and tested them for the visible light photocatalytic oxygen generation. The most active material was found to be (Zn/Cr)LDH with an atomic ratio of 4:2 that exhibits two absorption bands in the visible region at lambda(max) of 410 and 570 nm. It was found that the efficiency of these chromium layered double oxides for oxygen generation increases asymptotically with the Cr content. Using iron oxalate as chemical actinometer we have determined that the apparent quantum yields for oxygen generation (Phi apparent = 4 x mol oxygen/mol incident photons) are of 60.9% and 12.2% at 410 and 570 nm, respectively. These quantum yields are among the highest values ever determined with visible light for solid materials in the absence of light harvesting dye. The overall efficiency of (Zn/Cr)LDH for visible light oxygen generation was found to be 1.6 times higher than that of WO(3) under the same conditions.

CO2 Reduction: From the Electrochemical to Photochemical Approach

“…Many LDH compounds (such as Ti‐based LDHs) are known to be excellent photocatalysts for water splitting 150, 151, 152. Their potential in photocatalytic CO 2 reduction was first uncovered by Izumi's group in 2011 153.…”

Two‐Dimensional Hybrid Materials: Transferring Technology from Biology to Society

“…[53] Zn/Cr was reported as one of the most efficient photocatalysts for visible light water splitting (oxygen generation), due to its high quantum yield (incident photonto-oxygen conversion efficiency at a given wavelength). [54] Additionally the interstratification maintains the excellent photocatalytic activity for visible-light-induced O 2 generation; this in association with an electronic coupling between the component nanosheets and a protection of the LDH lattice by layered titanate. Enhanced photoelectrochemical water splitting was also reported for a hybridization using an aligned hierarchical nanoarray containing a ZnO core and a LDH nanoplatelet shell synthesized by a facile electrosynthesis method.…”

Kinetic properties and structural analysis of LaCrO3nanoparticles

“…The result clearly indicates interesting optical activity of LaCrO 3 in the UV and visible range. Two broad absorption edges at around 450 nm and 600 nm are associated with O 2p-Cr 3d(t 2g ) and Cr 3d(t 2g ) to Cr 3d(e g ) transitions, respectively [31]. The absorbance peak at around 600 nm (due to the transition of Cr 3d(t 2g ) to Cr 3d(e g )) is important for photocatalytic activity.…”