Z-scheme g-C3N4/Bi2O2[BO2(OH)] heterojunction for enhanced photocatalytic CO2 reduction

Abstract

Construction of Z-scheme heterojunction photocatalyst for CO2 photoreduction shows great significance as it holds strong redox ability and high charge separation efficiency. In this work, we developed a Z-scheme heterojunction photocatalyst graphitic carbon nitride (g-C3N4)/basic bismuth borate (Bi2O2[BO2(OH)]) by a simple high-energy ball milling method. The structure, surface element distribution and morphology of the composite samples were systematically analyzed. The photocatalytic performance of the samples was surveyed by CO2 reduction experiment under the simulated solar light irradiation. Almost all the g-C3N4/Bi2O2[BO2(OH)] composites show enhanced photocatalytic activity for converting CO2 into CO, and the highest CO production rate observed for g-C3N4/Bi2O2[BO2(OH)] (CNBB-3) among all the samples was determined to be approximately 6.09 µmol g−1 h−1, which is 2.78 times higher that of pristine g-C3N4. The largely strengthened photocatalytic CO2 reduction activity mainly originates from the formation of Z-scheme band structures between g-C3N4 and Bi2O2[BO2(OH)] benefiting for the efficient charge separation, which was confirmed by the photoeletrochemical, photoluminescence and ESR spectra. This study provides a new reference for fabrication of high-performance Z-scheme photocatalysts for CO2 reduction.