Facet Engineering Induced by Ce Doping: Enhanced (101) Facet Exposure for Boosted Photocatalytic Activity of ZnCdS Nanostructures

Photocatalytic hydrogen production utilizes solar energy, particularly the visible light portion, to decompose water into hydrogen, offering a clean and sustainable solution to the global energy crisis. Developing efficient and stable visible-light-driven photocatalysts is essential to improve hydrogen evolution efficiency. In this work, Ce-doped ZnCdS photocatalysts were synthesized via a hydrothermal method to enhance charge separation and photocatalytic performance under visible light irradiation. The 5% Ce-doped sample exhibited a hydrogen evolution rate 1.74 times higher than that of pure ZnCdS after 3 hours of irradiation. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) analyses reveal that Ce doping promotes the preferential exposure of highly active (101) facets and induces moderate grain growth, which reduces grain boundary defects and increases the number of active sites for H₂ generation. X-ray photoelectron spectroscopy (XPS) and electron paramagnetic resonance (EPR) analyses confirm that the Ce³⁺/Ce⁴⁺ redox centers lower the energy barrier for charge transfer and enhance electrical conductivity. Moreover, photoluminescence (PL) and photocurrent measurements demonstrate more efficient charge separation. As a result, the Ce-ZnCdS photocatalyst exhibits markedly improved visible-light responsiveness, photocatalytic efficiency, and structural stability, underscoring rare-earth doping as an effective strategy to optimize facet exposure and charge dynamics in ternary sulfide photocatalysts.