Plant-Based Phytochemicals for Synthesis of Z-Scheme In<sub>2</sub>O<sub>3</sub>/CdS Heterostructures: DFT Analysis and Photocatalytic CO<sub>2</sub> Reduction to HCOOH and CO
Pramod Madhukar Gawal, Animes Kumar Golder
Abstract
Photocatalytic CO 2 reduction shows potential for mitigating industrial emissions. Z-scheme In 2 O 3 /CdS(bio) heterostructures (25 nm, 217.0 m 2 g –1 surface area) with a more negative conduction band synthesized using phytochemicals present in Aegle marmelos with short microwave irradiation inhibit CdS(bio) photocorrosion forming SO 4 2– . In 2 O 3 /CdS(bio) increased the photocurrent density (0.82 μA cm –2 ) and CO 2 adsorption (0.431 mmol g –1 ) significantly compared to CdS(bio) and In 2 O 3 (bio) NPs. Heterostructures increased decay time and reduced PL intensity by 46.28 and 61.80% over those of CdS(bio) and In 2 O 3 (bio) NPs. Density functional theory (DFT)-optimized geometry, band structure analysis, and density of states (DOS) studies indicate that the DOS of CdS is modified with In 2 O 3 incorporation, enhancing charge separation. Optimal 0.4In 2 O 3 /CdS(bio) heterostructures exhibit remarkable CO 2 conversion to HCOOH/CO production of 514.4/162 μmol g –1 h –1 (AQY 4.44/2.45%), surpassing CdS(bio) and In 2 O 3 (bio) by 9 and 6.5 times, and retain their morphological and structural stability. This study provides valuable insight for developing bio-based CdS heterostructures for photocatalytic CO 2 reduction.