BiW11/Porous carbon nitride catalyst improves charge carrier separation efficiency for enhanced photocatalytic hydrogen evolution

Abstract

Solar water splitting has received tremendous attention as hydrogen emerges as a promising energy carrier. Carbon nitride (CN) is an ideal candidate for H2 evolution via water splitting on account of its unique optical and electrical properties. To mitigate photoexcited charge carriers recombination that has severely limited the photocatalytic activity of CN, a heterojunction photocatalyst of CN with monovacant bismuth tungstate (Na6[BiW11O38H]·22H2O, noted as BiW11) as a highly efficient photocatalyst is designed. Herein, the porous carbon nitride (PCN) is first fabricated via the gas template method, and then PCN with BiW11 is modified via the impregnation method. Series of BiW11-based PCN composites with different BiW11 loadings (BiW11/PCN-x, x represents the amount of BiW11) are created to merge complementary advantages of both materials. Visible-light-driven photocatalytic properties of BiW11/PCN-x composites have been examined with Na2S/Na2SO3 sacrificial agents. The hydrogen evolution rate of the BiW11/PCN-10 is 2.45 and 1.98 times than that of PCN and BiW11. This extraordinary photocatalytic activity is ascribed to increased attachment sites for catalysts and active centers for hydrogen reduction due to porous structure and significantly facilitated charge separation efficiency through the type-II heterostructure. The resulting composites would be a potential candidate strategy for the design of highly efficient polyoxomatalate-based photocatalysts for efficient hydrogen production applications.