CoAl LDH in-situ derived CoAlP coupling with Ni2P form S-scheme heterojunction for efficient hydrogen evolution

Abstract

Accelerating the separation and migration efficiency of photogenerated charge carriers and creating abundant active sites are the keys to the excellent H2 production performance of photocatalysts. In this work, two strategies, the construction of S-scheme heterojunction and the introduction of active P species, were carried out based on polyhedral Ni-MOF-74 and layered CoAl LDH, in order to accelerate the separation and migration of electron-hole pairs as well as create rich active sites for more improved photocatalytic H2 evolution performance. First, a delicate Ni-MOF-74/CoAl LDH S-scheme heterojunction was constructed, and then Ni-MOF-74/CoAl LDH was converted to CoAlP/Ni2P S-scheme heterojunction. That is, the active P species was introduced based on the presence of S-scheme heterojunction. More importantly, Ni-MOF-74/CoAl LDH S-scheme heterojunction photocatalyst exhibits visible improvement in H2 generation rate in comparison with single Ni-MOF-74 and CoAl LDH, which is attributed to the formation of S-scheme heterojunction undoubtedly. Further, CoAlP/Ni2P S-scheme heterojunction shows more improved H2 production performance than Ni-MOF-74/CoAl LDH, suggesting that P-modification is a high-efficiency means for enriching surface active sites and implementing the conversion of S-scheme heterojunction to S-scheme heterojunction.