Pharmaceutical pollutant as sacrificial agent for sustainable synergistic water treatment and hydrogen production via novel Z- scheme Bi7O9I3/B4C heterojunction photocatalysts

Abstract

The dual-function photocatalytic systems with a promising capability for hydrogen evolution and simultaneous pollutant degradation are surely a significant step towards waste-to-energy conversion goals. However, the performance of such photocatalysts is often limited by poor visible-light activity, charge separation and surface reverse reaction involving photogenerated electrons and radicals/intermediates. In this work, we report hydrothermal synthesis of novel Bi7O9I3/B4C (BIBC) heterojunction photocatalyst for advanced Norfloxacin antibiotic degradation with simultaneous hydrogen evolution under visible light. In particular, BIBC-30 heterojunction shows H2 evolution rate of 812 μmol g−1h−1 with simultaneous 94.2% NFN removal which are much higher than bare B4C (∼6 times) and Bi7O9I3 (∼4 times). Under oxic/aerobic conditions too, a high 456.3 μmol g−1h−1H2 evolution with nearly complete norfloxacin degradation was achieved. The low band gap of Bi7O9I3 and presence of metallic Bio extends the absorbance to NIR region and B4C enlarges the surface area of junction along with suppression of the back reaction. It was observed that BIBC heterojunction exhibits manifolds H2 evolution rate with NFN as sacrificial agent (18.3% apparent quantum efficiency) is manifolds higher than pure water, methanol, triethanolamine and rhodamine B. An effective Z-scheme charge transfer facilitated by Bio is active in the intimately coupled heterojunction with suitably placed energy bands. This work shows that waste to energy conversion can be promisingly achieved by performing H2 evolution and pollutant removal simultaneously.