Oxygen-vacancy engineering approach to bismuth basic nitrate/g-C3N4 heterostructure for efficiently photocatalytic hydrogen evolution

Abstract

Formation of oxygen vacancy is emerging as one type of promising defect engineering in the preparation of inorganic functional composites. In this work, a novel composite upon the calcination of the nanosheets Bi6O6(OH)3(NO3)3·1.5H2O (BBN) and g-C3N4 was prepared. A large amount of oxygen vacancies was revealed by electron spin resonance (ESR) and Raman spectroscopy. These intriguing structural characters render the as-prepared composite with excellent interfacial charge transfer and photo-stimulated response as shown by electrochemical impedance spectroscopy (EIS) and photocurrent measurement. Upon visible-light activation, such composite enables photocatalyse H2 evolution with a rate of 181 μmol h−1 g−1 around the 4.2 times that of pure g-C3N4 as a reference. Such composite catalyst exhibits excellent recycling and reusable behaviors. The formation of BBN/CN heterojunction and the existence of oxygen vacancies are the main reasons for the distinctly improvement of its photocatalytic activity, which has been verified by theoretical calculations.