Boosting visible-light-driven water splitting over LaTaON2via Al doping

Abstract

LaTaON 2 is an attractive visible-light-active photocatalyst for water splitting due to its broad visible light absorption as far as 650 nm and proper band edge positions. Notwithstanding these promising properties, LaTaON 2 generally exhibits poor photocatalytic activity because of its high defect concentration that severely hinders charge separation. Here, LaTaON 2 has been modified by doping Al into the Ta sublattice, i.e., LaTa 1−x Al x O 1+y N 2−y (0 ≤ x ≤ 0.20). Al doping not only inhibits the defect concentration and increases surface hydrophilicity but also maintains the desired visible light absorption of LaTaON 2 . These important modifications substantially ameliorate the charge separation conditions within LaTaON 2 and are responsible for a much enhanced photocatalytic performance for water redox reactions under visible light illumination. Under optimal conditions, the Al-doped LaTaON 2 delivers an apparent quantum efficiency of 1.17% at 420 ± 20 nm for water oxidation into O 2 , outperforming most LaTaON 2 -based photocatalysts. These findings highlight Al as a useful dopant to open up the photocatalytic potential of metal oxynitrides whose activity is often undermined by a high defect concentration.

A catalyst support for direct-ammonia solid-oxide fuel cell anodes based on lanthanum titanium oxynitride

“…Metal oxynitrides and nitrides have received significant attention as catalysts particularly for water splitting, 28 electrocatalytic reduction of nitrogen to ammonia, 29 and CO 2 photoreduction. 30 Recent research by Wahab et al investigates the possibility of utilizing early-transition metal-based oxides/nitrides as an efficient electrocatalyst for hydrogen generation from saline water.…”

“…Previous reports have shown that the introduction of Fe can dramatically decrease the internal resistance of the cell, 23 thereby suppressing the anodic overpotential of the cell. Addition of Fe also achieves improvements in the H 2 oxidation 25,26 Metal oxynitrides and nitrides have received signicant attention as catalysts particularly for water splitting, 28 electrocatalytic reduction of nitrogen to ammonia, 29 and CO 2 photoreduction. 30 Recent research by Wahab et al investigates the possibility of utilizing early-transition metal-based oxides/ nitrides as an efficient electrocatalyst for hydrogen generation from saline water.…”

Advanced materials and energy technologies towards carbon neutrality

“…Wan et al [16] have made a CdS/PbTiO 2 /TiO 2 heterostructure catalyst with combined interfacial electrical and ferroelectric fields which can efficiently separate charges and lead to two orders of magnitude improvement of photocatalytic hydrogen production. In addition, Yang et al [17] have doped Al into the lattice of LaTaON 2 , which maintains the light absorption property, inhibits the defect concentration, and increases the surface hydrophilicity of the catalysts, leading to much enhanced photocatalytic water oxidation performance. Yin et al [18] have prepared a CoO x /Ni:COOH bilayer-protected n-Si photoanode which is stable under oxygen evolution with improved onset potential and photocurrent density.…”