UiO-66(-NH2) crystal-decorated Cu7S4 snowflake-like nanoarchitectures with synergistic charge migration for enhanced photocatalytic H2 evolution and N2 fixation

Abstract

The fabrication of template-free dendritic copper sulphide phase-coupled metal–organic framework (MOF) heterostructures is an innovative approach for boosting light harvesting property and efficacy towards the photoreduction of atmospheric molecules. In this study, the rational construction of UiO-66(-NH₂)/Cu₇S₄ (UNCS) n–p heterostructures with snowflake-like morphology via a facile reflux technique for photocatalytic H₂ production and N₂ fixation reactions is reported. The prepared n–p heterostructure materials were well characterized using various structural, morphological, and spectroscopic techniques to comprehend their physicochemical and optoelectronic features. The fine dispersion of UiO-66(-NH₂) (UN) nanocrystals on the surface of snowflake-like Cu₇S₄ endows increased specific surface area and strong interfacial contact, which are favourable for the enhanced separation and facile migration of photogenerated charge species. In addition, the well-organized snowflake-like architecture with lush branches allows multiple reflection and scattering of the incident light leading to enhanced absorption. The UNCS heterojunction displayed superior photocatalytic H₂ evolution (3110 μmol g⁻¹ h⁻¹) and NH₃ production (374 μmol g⁻¹ h⁻¹) to pure UN and Cu₇S₄ (CS) semiconductors. The higher photocatalytic performance of the heterostructure is attributed to the morphological advantages and formation of a tight contact interface and an n–p heterojunction, which improve rapid interfacial charge migration. This study provides a new insight into the fabrication of n–p heterostructure photocatalysts for converting solar energy into a clean energy and value-added chemicals.