Advanced Photocatalytic Strategies for Environmental Remediation and Green Hydrogen Production: From Bench to Scalable Innovation
Abstract
The increasing global demand for clean water and sustainable energy has intensified the pursuit of innovative material solutions capable of addressing both environmental pollution and energy challenges. This presentation highlights recent advances in the synthesis and application of semiconductor-based heterojunction photocatalysts for the degradation of organic and inorganic pollutants, microbial inactivation in contaminated water, and the future direction toward green hydrogen production using 3D-printed photoelectrodes.
A ZnO-BiOI heterojunction was developed and successfully employed in the efficient degradation of methyl orange, 2-chlorobiphenyl, cyanide, and thiocyanate, achieving near-complete removal within remarkably short irradiation times under simulated solar light. The influence of photocatalyst mass and pollutant concentration on photocatalytic performance was systematically evaluated, revealing that both parameters critically affect degradation kinetics, ROS generation, and light penetration efficiency.
Complementing this, a parallel study investigated the degradation of 4-nitrophenol using ZnO-WO₃ composites. The results underscore the need for optimization of pH and stability under operational conditions. Building upon these findings, microbial inactivation experiments under natural sunlight using ZnO/WO₃-based composites and activated coal fly ash demonstrated complete elimination of E. coli within 4–6 hours, marking a promising step toward decentralized water treatment systems.
Looking ahead, the presentation introduces a future research framework centered on the development of 3D-printed ZnO-WO₃ composite photoelectrodes for photoelectrochemical (PEC) water splitting. This interdisciplinary approach combines advanced materials design with additive manufacturing to overcome the intrinsic limitations of conventional electrodes—offering a scalable, efficient, and sustainable solution for hydrogen production.
This body of work bridges the gap between photocatalysis for environmental remediation and green energy conversion technologies, underscoring the versatility of semiconductor heterostructures in achieving dual sustainability goals.
Biography
Dr. Darlington Ashiegbu is a Senior Postdoctoral Research Fellow and Independent Researcher in the SIMMET (Sustainable and Innovative Metals and Minerals Extraction Technologies) Research Group at the University of the Witwatersrand, Johannesburg, South Africa. He holds a PhD in Chemical Engineering, with expertise in water and wastewater treatment, advanced photocatalysis, and nanomaterial synthesis. His research has focused on the design and application of ZnO-based heterojunction photocatalysts for the degradation of organic and inorganic pollutants, including industrial dyes, chlorinated compounds, cyanides, and microbial contaminants. Dr. Ashiegbu is currently developing novel 3D-printed ZnO-WO₃ photoelectrodes for solar-driven photoelectrochemical (PEC) hydrogen production, aiming to bridge materials science and green energy innovation. He has authored peer-reviewed publications on environmental photocatalysis and plays an active role in postgraduate supervision and collaborative research.
