Morphological regulation of sulfur-vacancy-rich CdS for tunable CO2 photoreduction under visible light irradiation†

In this work, morphological control with a series of sulfur-vacancy-rich CdS photocatalysts has been achieved toward the optimization of their performances in CO₂ photoreduction. Results show that sulfur-vacancy-rich CdS nano-platelets (p-CdS-Vs) exhibit the highest CO₂ photoreduction activity with a CO yield of 4058.5 μmol h⁻¹ g⁻¹, which is 10 and 6 times those of sulfur-vacancy-rich CdS nanowires (w-CdS-Vs, 372.8 μmol h⁻¹ g⁻¹) and nanorods (r-CdS-Vs, 638.7 μmol h⁻¹ g⁻¹), respectively, amongst the highest numbers for CdS-based photocatalysts reported hitherto. The superior CO₂ photoreduction performance of p-CdS-Vs is attributable to its high efficiency of electron transport and suppressed recombination of photogenerated charge carriers. A mechanistic study indicates the critical role of surface sulfur vacancies that provide a microenvironment to trap unpaired electrons for the separation of photogenerated carriers so that the photocatalytic efficiency of CO₂-to-CO reduction is largely improved in this current system.