Systematic studies of Bi2O3 hierarchical nanostructural and plasmonic effect on photoelectrochemical activity under visible light irradiation

Abstract

The effect of Ag plasmonic nanowire layers on the hierarchical nanostructure of Bi2O3 photoelectrodes for water splitting under visible light irradiation was studied for the first time. In addition, the impact of various Bi2O3 nanostructures on light harvesting and generation of relative photocurrent have been investigated. The cubic structure of Bi2O3 was confirmed using X-ray diffraction analysis. Optical bandgaps of 2.14 and 2.30 eV have been achieved for the Bi2O3 nanoparticles and nanoflowers photoelectrodes (BP and BF), respectively. The photocurrent density (J) of the BP featuring Ag plasmonic layer photoelectrode (Ag/BP) was 6.47 mA cm(-2), and was higher than that of the BF featuring Ag plasmonic layer photoelectrode (Ag/BF), which was 4.33 mA cm(-2). These values were approximately 647 and 2165 times higher than those of BP and BF, respectively. However, the J value of BP was 2.13 mA cm(-2) higher than that of BF. The superior J values of Ag/BP and Ag/BF were attributed to the increased light absorption and reduced electron-hole recombination rate at the time scale beyond a few 10(-12) s, owing to the Ag nanowires. In addition, the plasmonic field was able to reduce the charge recombination rate of the nanostructured electrodes in reactor cells.