Surface functionalized visible light-responsive yttrium orthovanadate for photocatalytic hydrogen production

Yttrium orthovanadate (YVO4), a wide-bandgap photocatalyst was tuned into a visible responsive material by anchoring an organic framework on the surface of YVO4 nanoparticles using polyethyleneimine (PEI). The surface organic framework was identified as the decomposed PEI derivatives with the carbonyl and carboxylic acid functional groups by the FTIR and XPS analyses. The top of the valence band (VB) was raised and the bottom of the conduction band was moved down; hence, the band gap of YVO4 was reduced to absorb the light in the visible region for all three synthesized samples, which was confirmed by DRS UV-Vis analysis. The functional groups facilitated more water molecules on the YVO4 surface via hydrogen bonding; hence, the YVO4 surface acquired superhydrophilicity. Among the three YI, YII, and YIII samples synthesized with three different calcination temperatures of 80, 260 and 400 oC respectively, YII showed many advantageous photocatalytic properties. The optimum loading of organic compounds obtained on YII surface at 260 oC, which improved the surface area, visible light absorption, hydrophilicity, and exciton's life. Hence, YII showed a better performance of 3.75 mmol h-1g-1cat H2 production than YI and YII. This work interestingly revealed the influence of calcination temperature on surface functionalization and the performance of catalytic materials.