Short abstract:

The excessive reliance on fossil fuels has intensified the global energy crisis and greenhouse gas emissions, necessitating sustainable solutions. Photocatalytic CO2 reduction (PCO2R) offers a green approach to simultaneously mitigate CO2 emissions and produce value-added fuels, mimicking natural photosynthesis in plants (Fig.1). This doctoral work focuses on developing environmentally benign routes for synthesizing CdS nanostructures, nanoparticles, nanorods, and quantum dots, using phytochemicals from Aegle marmelos and biomass-derived carbon dots. These nanostructures were further engineered into composites and heterojunctions (CQDs/CdS, In2O3/CdS, CDs/CdS QDs, SnO2/CdS QDs, CuO/CdS QDs) to enhance light absorption, charge separation, and stability, thereby overcoming photocorrosion and recombination limitations. The optimized systems exhibited superior photocurrent response, CO2 adsorption capacity, and long-term stability, achieving selective reduction of CO2 into methanol, ethanol, formic acid, carbon monoxide, and hydrogen with high apparent quantum efficiencies. Density functional theory (DFT) studies provided mechanistic insights, revealing favorable band alignment and intermediate stabilization that govern product selectivity. This research highlights the potential of bio-based CdS heterostructures as sustainable photocatalysts for efficient CO2-to-fuels conversion under visible light.

The thesis entitled “Development of bioinspired catalyst for photocatalytic CO2 reduction to value-added chemicals” is divided into five objectives, which are listed below. Click here for the detailed publication profile of my thesis work

Objective 1:To synthesis CQDs/CdS nanocomposites in a vegetal route for photocatalytic reduction of CO2 to methanol under visible light 

Objective 2: To investigate plant-based phytochemicals for the synthesis of Z‑scheme In2O3/CdS heterostructures and its DFT analysis for photocatalytic CO2 reduction to HCOOH and CO 

Objective 3: To perform experimental and theoretical studies on photocatalytic CO2 reduction to HCOOH by biomass-derived carbon dots embedded phytochemical-based CdS quantum dots 

Objective 4:To synthesize Z-scheme SnO2/CdS heterostructure and its DFT study for photocatalytic CO2 reduction to methanol and hydrogen 

Objective 5: To construct phytochemical-based synthesis of p-n Junction CuO/CdS heterostructures for photocatalytic carbon dioxide reduction to ethanol and carbon monoxide