Citrate-directed phase engineering of CdS-CdCO3@g-C3N4 heterojunctions for enhanced solar photocatalysis

초록

Identifying the key properties of photocatalysts and optimizing their heterojunction phase structures are indispensable for achieving efficient charge separation and improving solar-driven photocatalysis. Herein, the phase transformation and photocatalytic performance of CdS-based composites were investigated, focusing on the hexagonal (H) wurtzite and cubic (C) zinc blende structures formed with and without citrate addition, respectively. As-synthesized CdS with hexagonal and cubic crystalline phases was hydrothermally treated with g-C3N4 nanosheets (NSs), during which an additional phase of CdCO3 spontaneously emerged around the CdS surface. This hydrothermal method led to the fabrication of ternary heterojunction composites, CdS(H)-CdCO3@g-C3N4 and CdS(C)-CdCO3@g-C3N4. The photocatalytic activity of CdS(H)-CdCO3@g-C3N4 was 99.87 % towards methyl orange (MO) degradation (10 ppm, 100 mL) within 120 min under simulated solar light, which was 5.6 times higher performance than that of its cubic analog, highlighting the potential of the CdS(H)-CdCO3@g-C3N4 for improving the photocatalytic activity of CdS-based composites under simulated solar light. The optimal degradation efficiency was achieved under operational conditions of initial MO pH approximate to 7, catalyst amount of 0.030 g/ 100 mL, and 10 ppm MO dye. This study emphasized the critical role of citrate additives in the formation and stabilization of hexagonal CdS structures for applications in green energy production and environmental remediation.

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