Cu-MOF assisted synthesis of CuS/CdS(H)/CdS(C): Enhanced photocatalytic hydrogen production under visible light

CuS/CdS(H)/CdS(C) photocatalysts were synthesized via the hydrothermal method by employing thiourea, Cd(CH3COO)2·3H2O and copper 1,4-benzenedicarboxylate MOF (CuBDC). The photocatalysts were characterized by XRD, XPS, BET, TEM and UV–vis diffuse reflectance spectra. Interestingly, hexagonal CdS (CdS(H)) and cubic CdS (CdS(C)) were formed with phase junctions in one step when CuBDC was introduced in the synthesis process, in addition, CuS nanoparticles were deposited on CdS. However, only hexagonal CdS was obtained without CuBDC. It demonstrated that CuBDC was not only the precursor of CuS but also the structural modifier for CdS. With the reduction of re-combination of photo-induced electrons and holes caused by phase junctions and the enhancement of visible-light absorptions due to the loading of CuS, all CuS/CdS(H)/CdS(C) photocatalysts had higher photocurrent densities under visible-light irradiation, and consequently the higher rates of H2 production than pure CdS(H). Typically, the catalyst with 2.89 wt% of Cu showed a highest rate of H2 evolution at 2042 μmol/g/h.