Energy band engineering of Bi2O2.33CdS direct Z-scheme heterojunction for enhanced photocatalytic reduction of CO2

In this work, a Bi2O2.33CdS direct Z-scheme heterojunction was fabricated based on energy band engineering. The Bi2O2.33 core nanoflakes were first synthesized by electrodeposition which was followed by an annealing process to fabricate this heterojunction. Then the CdS shell was deposited on Bi2O2.33 nanoflakes utilizing the solution method, during which a suitable concentration of CdCl2 solution was used for forming a homogeneous and continuous integrated CdS shell. A space charge region and an internal electric field from CdS (+) to Bi2O2.33 (−), which drove a direct Z-scheme charge transfer process, were formed at the interface. The Bi2O2.33CdS exhibited excellent photocatalytic performance for CO2 reduction mainly attributed to the satisfactory photoinduced charge separation and transport efficiency in the direct Z-scheme heterojunction. The photocatalytic CO2 reduction ability of Bi2O2.33CdS was significantly enhanced compared with single Bi2O2.33 or CdS, with a CO yield rate of ca. 2.9 μmol/(cm2 h) under a 300 W Xe lamp. The reduction of CO2 to CO demonstrated 94.0% selectivity.