Titanium dioxide nanoparticles purifying polluted water.

Clean Water Revolution: How Photocatalysis is Transforming Environmental Remediation

Kai Mendoza in Climate & Environment August 2025 • 4 min read.

"Explore the groundbreaking achievements of Ezio Pelizzetti and the evolution of photocatalysis in revolutionizing water purification and environmental protection."

For over four decades, photocatalysis in heterogeneous media has undergone significant development. This article is dedicated to the memory of Prof. Ezio Pelizzetti, a pioneer in the field whose work has had a lasting impact. Pelizzetti, who was the Rector of the University of Torino, Italy, until his death in the summer of 2017. This is a personal overview of some of Pelizzetti's achievements and contributions to photocatalysis. His work has made a big impact in the application of photocatalysis to environmental remediation, particularly of aquatic ecosystems contaminated with different types of organic and inorganic contaminants.

Photocatalysis, involves light-driven chemical reactions, holds immense promise for addressing environmental challenges. Central to this technology is titanium dioxide (TiO2), a semiconductor material that acts as a photocatalyst. When TiO2 is exposed to ultraviolet (UV) or visible light, it becomes activated and initiates a series of redox reactions that can degrade pollutants and purify water. Its stability, nontoxicity, and cost-effectiveness have propelled it to the forefront of photocatalytic research and applications.

The term photocatalysis was first used by the Russian scientist Plotnikow in 1910, and later by Landau, who noted its potential for pollutant breakdown even with insoluble catalysts, setting the stage for heterogeneous photocatalysis. However, progress was slow, with debates over whether materials acted as catalysts or mere photosensitizers. The field experienced a resurgence in the late 1970s, driven by the oil crisis and breakthroughs from researchers like Bard, who explored TiO2 for oxidation reactions and co-catalyst use.

Ezio Pelizzetti's Pioneering Contributions to Photocatalysis

Titanium dioxide nanoparticles purifying polluted water.

Ezio Pelizzetti played a pivotal role in advancing photocatalysis, particularly in water purification and environmental remediation. His work focused on using semiconductor materials like titanium dioxide (TiO2) to degrade pollutants in aquatic ecosystems. Pelizzetti's approach involved harnessing light energy to activate TiO2, initiating redox reactions that break down organic and inorganic contaminants.

Pelizzetti’s research extended to examining and improving TiO2's effectiveness through various methods, including combining it with other semiconductors like cadmium sulfide (CdS). This combination enhanced the photocatalytic activity by facilitating electron transfer between the materials, leading to better degradation of pollutants. Pelizzetti and his team also investigated the use of co-catalysts, such as platinum, to further improve the efficiency of TiO2 in photocatalytic reactions.

Pelizzetti’s extensive research covered a wide array of applications:

Degradation of Haloaromatic Pollutants: Successfully breaking down harmful substances using TiO2.
Photocatalytic Hydrogen Production: Pioneering methods to produce hydrogen using semiconductor materials.
Removal of Toxic Substances: Efficiently eliminating cyanide and metallic ions from contaminated water.
Surfactant Decomposition: Addressing water contamination by breaking down various surfactants.

His team made significant strides in the photocatalytic degradation of organic pollutants, achieving complete conversion to CO2 and demonstrating the technology's potential for water treatment. This research was crucial in showing that photocatalysis could be a viable solution for treating water contaminated with pollutants, thus paving the way for more sustainable environmental practices.

Looking Ahead: The Future of Photocatalysis

Photocatalysis has evolved from a laboratory curiosity to a promising technology for addressing pressing environmental challenges. Ongoing research focuses on enhancing the efficiency, expanding the range of treatable pollutants, and harnessing solar energy for sustainable water purification and pollution control. As we continue to innovate, photocatalysis holds the potential to transform environmental remediation and create a cleaner, healthier world for future generations.

About this Article -

This article was crafted using a human-AI hybrid and collaborative approach. AI assisted our team with initial drafting, research insights, identifying key questions, and image generation. Our human editors guided topic selection, defined the angle, structured the content, ensured factual accuracy and relevance, refined the tone, and conducted thorough editing to deliver helpful, high-quality information.See our About page for more information.

This article is based on research published under:

DOI-LINK: 10.1016/j.cattod.2018.10.063, Alternate LINK

Title: Two Decades Of Ezio Pelizzetti’S Achievements And Contributions To Photocatalysis – A Personal Recollection

Subject: General Chemistry

Journal: Catalysis Today

Publisher: Elsevier BV

Authors: Nick Serpone

Published: 2020-01-01

Everything You Need To Know

What is photocatalysis and why is it important for environmental remediation?

Photocatalysis is a process that uses light to drive chemical reactions, often involving a semiconductor material like titanium dioxide (TiO2). When TiO2 is exposed to UV or visible light, it becomes activated and initiates redox reactions that can degrade pollutants and purify water. This technology is valuable because it offers a sustainable way to address environmental challenges, particularly in water purification.

What were Ezio Pelizzetti's primary contributions to the field of photocatalysis?

Ezio Pelizzetti made significant contributions to photocatalysis, particularly in the application of semiconductor materials like titanium dioxide (TiO2) for water purification. His research focused on using light energy to activate TiO2, initiating redox reactions that break down organic and inorganic contaminants in aquatic ecosystems. Pelizzetti's work also involved enhancing TiO2's effectiveness by combining it with other semiconductors and co-catalysts.

Why is titanium dioxide (TiO2) so important in photocatalysis, and how can its effectiveness be improved?

The use of titanium dioxide (TiO2) in photocatalysis is central due to its stability, nontoxicity, and cost-effectiveness. When TiO2 is exposed to ultraviolet (UV) or visible light, it becomes activated and initiates redox reactions. These reactions are capable of degrading a wide range of pollutants. Further enhancements, such as combining TiO2 with other semiconductors like cadmium sulfide (CdS) or co-catalysts like platinum, improve its efficiency and broaden its applicability in environmental remediation.

What specific environmental problems has photocatalysis been used to address, and what are some notable successes?

Photocatalysis has been applied to address numerous environmental issues, including the degradation of haloaromatic pollutants, photocatalytic hydrogen production, removal of toxic substances like cyanide and metallic ions from contaminated water, and the decomposition of surfactants. The success in completely converting organic pollutants to CO2 highlights its potential for comprehensive water treatment and sustainable environmental practices. However, the energy source must be considered, as UV or visible light is required, which may add to the cost. The long term stability of TiO2 under various conditions may need to be considered for real-world application.

What are the key areas of focus for future research in photocatalysis, and how could these advancements impact environmental remediation?

Future research in photocatalysis is focusing on enhancing the efficiency of photocatalytic processes, expanding the range of pollutants that can be treated, and harnessing solar energy to make the technology more sustainable. These advancements aim to transform environmental remediation by creating more effective and environmentally friendly solutions for water purification and pollution control. The aim is to create a cleaner and healthier world for future generations. Also, one aspect is to increase the use of visible light, since TiO2 works best in UV light.