A nanocrystalline oxygen-deficient bismuth oxide as an efficient adsorbent for effective visible-light-driven photocatalytic performance toward organic pollutant degradation.

In this work, a simple binary oxygen-deficient BiO oxide was prepared, and its crystal structure, optical property, band structure and electronic structure were systematically investigated. Plane-wave-based density functional theory (DFT) calculations were also carried out to determine that BiO is a typical indirect-gap semiconductor with the bandgap of 1.1 eV. BiO adsorbed ca. 99% of rhodamine B and methyl orange, ca. 95% of methylene blue and ca. 80% of phenol in the dark within initial 30 min. The interaction of the oxygen-deficient structure-induced hydroxyls with pollutant molecules is responsible for the excellent adsorption capacity. Due to its excellent adsorption capacity, BiO showed much higher photocatalytic degradation activity toward these pollutants (except for methylene blue) under visible light irradiation than the well-studied BiO, BiO and P25, which had poor or negligible adsorption capacity toward the pollutants. Methylene blue was degraded by BiO with further Pd loading. The photocatalytic mechanism of the oxygen-deficient BiO were explored. The scavenging test results showed that direct h oxidation contributes to the high photocatalytic activity of the oxygen-deficient BiO. This study highlights the potential of developing BiO-based materials as a new class with both excellent adsorption capacity and highly efficient photocatalytic activity toward versatile pollutants.