Photophysical, optical, and photocatalytic hydrogen production properties of layered-type BaNb2-xTaxP2O11 (x=0, 0.5, 1.0, 1.5, and 2.0) compounds

Layered-type metal phosphates of BaNb2-xTaxP2O11 (x = 0, 0.5, 1.0, 1.5, and 2.0) were synthesized using a solid-state reaction method. The photophysical, optical, and photocatalytic hydrogen production properties of the resulting powders were investigated for the first time. Phase-pure and homogeneous powders with irregular morphologies were obtained at a calcination temperature of 1200 degrees C. As the Ta content increased, the interlayer distance along the c-axis increased by up to 0.14%. Additionally, the optical bandgap values increased from 3.32 to 3.59 eV. The energy band positions were estimated from the Mott-Schottky measurements. BaNb2P2O11 ( x = 0) exhibited the lowest conduction band edge position (-0.14 V vs. the normal hydrogen electrode, NHE), which is located above the water reduction potential (0.0 V vs. NHE). In comparison, BaTa2P2O11 (x = 2.0) exhibited the highest conduction band edge position (-0.29 V vs. NHE), comparable to that of TiO2. The photocatalytic activity for hydrogen produced from splitting water was measured under ultraviolet light irradiation. Notably, BaTa2P2O11 exhibited the highest activity (7.3 mu mol/h), which was 15 and 10 times larger than BaNb2P2O11 (0.5 mu mol/h) and nanoTiO(2) (0.7 mu mol/h), respectively. The activity of BaTa2(P2)O(11) increased to 24.4 mu mol/h after deposition of the NiOx co-catalyst (1 wt.%), which remained stable during continuous operation (similar to 35 h). (C) 2022 Published by Elsevier Ltd on behalf of The editorial office of Journal of Materials Science & Technology.

Automated summary

Layered-type metal phosphates of BaNb2-xTaxP2O11 were synthesized and their photophysical, optical, and photocatalytic hydrogen production properties were investigated. The interlayer distance and optical bandgap values varied with the increase of Ta content.