Efficient photocatalytic activity over α-MnS/ZIF-67 p-n junction: Revealing the synergistic effects of exposed crystal facets and built-in electric field mechanism

In this investigation, we explored two series of composites comprising p-type α-MnS with selectively exposed {001} or {111} facets, coated with n-type ZIF-67 nanoparticles, to enhance the photocatalytic activity on Rhodamine B (RhB) degradation. The influence of the crystal facet orientation and the p-n junction on the photocatalytic efficacy was also well studied. The α-MnS/ZIF-67 composites displayed enhanced separation of charge carriers and superior light absorption capabilities, benefiting for efficient photocatalysis. The composites with cubic α-MnS morphology exhibited a pronouncedly higher photocatalytic activity relative to those with octahedral α-MnS morphology. The composition of α-MnS with ZIF-67 constructed the formation of a p-n junction with build-in electric field, extending the response into the visible region and promoting the mobility of charge carriers, thereby improving the photocatalytic performance. Our findings revealed that superoxide radicals (O₂^-) were the major reactive species in the photocatalytic degradation process. This study contributes novel insights into the development of high-performance and stable metal-organic framework (MOF)-based photocatalysts through the crystal facet engineering and the construction of p-n junctions.