Date of Defense
29-11-2025 2:00 PM
Location
1077- building F1
Document Type
Thesis Defense
Degree Name
Master of Science in Chemical Engineering (MSChE)
College
College of Engineering
Department
Chemical and Petroleum Engineering
First Advisor
Dr. Muhammad Tahir
Abstract
Green hydrogen production has received great attention in recent years as a solution to mitigate greenhouse gas emissions resulted by burning fossil fuels. This thesis focuses on development of photocatalytic water splitting green hydrogen production under visible light irradiation of g-C3N4 based sulfurized naturally occurring serpentine rock and oxysulfide perovskite nanocomposites. This work reveals the effect of partial sulfurization of co-catalysts to boost charge generation, charge transfer, and light absorption. The presented work determined the potential of sulfurizing naturally occurring rocks and minerals acting as support and enhanced co-catalysts that exhibit narrower band gaps, with sulfur rich sites for visible light hydrogen production, simultaneously. Moreover, it demonstrated the potential of enhancing photocatalytic green hydrogen production of g-C3N4 once coupled with a partially sulfurized co-catalyst, attributing to the formation of competent heterojunctions with efficient charge separation. Characterization techniques implemented in this study are XRD, FTIR, XPS, SEM, TEM, PL, UV-vis, EIS, CV, and several analysis methods like Tauc plot and Mott-Schottky curve. Photocatalytic water splitting green hydrogen production performance was evaluated through evolved hydrogen yield and apparent quantum efficiency at varying composite loading, varying sacrificial agents, sea water, deionized water, and at prolonged durations for stability evaluation. The photocatalytic hydrogen production was investigated using 2D/2D novel oxysulfide perovskite LaCoOxS3-x ultrathin nanosheets (LaCoOxS3-x/g-C3N4), naturally occurring serpentine (Serp/g-C3N4), and sulfurized naturally occurring serpentine (S-Serp/g-C3N4). The LaCoOxS3-x/g-C3N4 composite exhibited the highest apparent quantum yield of 2.005%, achieving an average hydrogen yield of 132.7 μmol g-1 h-1, surpassing the bare g-C3N4 with 46-fold, while the second-best composite is S-Serp/g-C3N4 with 11.6 μmol g-1 h-1 and 7.7-fold enhancement over bare g-C3N4. This research presents a promising solution for enhancing photocatalytic green hydrogen production of g-C3N4 based composites and initiates new paths in tackling g-C3N4 limitations by coupling with oxysulfide perovskite or sulfurized naturally occurring rocks and minerals.
Included in
SULFURIZED SERPENTINE AND PEROVSKITE ASSISTED GRAPHITIC CARBON NITRIDE NANOCOMPOSITES FOR PHOTOCATALYTIC GREEN HYDROGEN PRODUCTION
1077- building F1
Green hydrogen production has received great attention in recent years as a solution to mitigate greenhouse gas emissions resulted by burning fossil fuels. This thesis focuses on development of photocatalytic water splitting green hydrogen production under visible light irradiation of g-C3N4 based sulfurized naturally occurring serpentine rock and oxysulfide perovskite nanocomposites. This work reveals the effect of partial sulfurization of co-catalysts to boost charge generation, charge transfer, and light absorption. The presented work determined the potential of sulfurizing naturally occurring rocks and minerals acting as support and enhanced co-catalysts that exhibit narrower band gaps, with sulfur rich sites for visible light hydrogen production, simultaneously. Moreover, it demonstrated the potential of enhancing photocatalytic green hydrogen production of g-C3N4 once coupled with a partially sulfurized co-catalyst, attributing to the formation of competent heterojunctions with efficient charge separation. Characterization techniques implemented in this study are XRD, FTIR, XPS, SEM, TEM, PL, UV-vis, EIS, CV, and several analysis methods like Tauc plot and Mott-Schottky curve. Photocatalytic water splitting green hydrogen production performance was evaluated through evolved hydrogen yield and apparent quantum efficiency at varying composite loading, varying sacrificial agents, sea water, deionized water, and at prolonged durations for stability evaluation. The photocatalytic hydrogen production was investigated using 2D/2D novel oxysulfide perovskite LaCoOxS3-x ultrathin nanosheets (LaCoOxS3-x/g-C3N4), naturally occurring serpentine (Serp/g-C3N4), and sulfurized naturally occurring serpentine (S-Serp/g-C3N4). The LaCoOxS3-x/g-C3N4 composite exhibited the highest apparent quantum yield of 2.005%, achieving an average hydrogen yield of 132.7 μmol g-1 h-1, surpassing the bare g-C3N4 with 46-fold, while the second-best composite is S-Serp/g-C3N4 with 11.6 μmol g-1 h-1 and 7.7-fold enhancement over bare g-C3N4. This research presents a promising solution for enhancing photocatalytic green hydrogen production of g-C3N4 based composites and initiates new paths in tackling g-C3N4 limitations by coupling with oxysulfide perovskite or sulfurized naturally occurring rocks and minerals.