Synergistic effect of homojunction and Ohmic junctions in CdS boosting spatial charge separation for U(VI) photoreduction

Photo-excited holes usually migrate to the surface of the catalyst and rapidly recombine with electrons, reducing the photocatalytic reduction efficiency of uranium(VI) (U(VI)) in radioactive wastewater. Consequently, we employed a straightforward synthesis technique to meticulously shape and manipulate the morphology of CdS to precisely construct CdS-Ni dandelion-like composites with different aspect ratios. Briefly, the introduction of crystal facet homojunction with Ohmic contacts in this unique morphology siqnificantly improves the photocatalytic efficiency. Temperature-dependent photoluminescence spectroscopy (TD-PL) verifies that the composite material positively effects on the dissociation of excitons. Within 30 min, CdS(002)/(102)/Ni-4 removed 98% of the uranium content in solution and showed a rather high apparent rate constant (0.114 min⁻¹), which was 4.8 times higher than that of CdS nanospheres (NSs) (0.024 min⁻¹) and 3.7 times higher than that of CdS nanorods (NRs) (0.031 min⁻¹). This is much higher the most reported photocatalysts for U(VI) reduction. Even after 5 consecutive cycles, the photocatalytic efficiency only decreased by 7%. This offers a fresh perspective on constructing a new perspective for building a green, efficient, and multi mechanism collaborative catalytic system to remediate environmental pollution.