A research team has published a review summarizing synthetic design strategies for developing high-performance photocatalysts. Their review provides a guide for developing these photocatalysts for clean energy applications, such as carbon dioxide reduction and plastic waste photoreforming, and it contributes to the advancement of sustainable energy technologies.
The review is published in the journal Carbon Future on December 24, 2024.
Photocatalysis, where a catalyst speeds up a chemical reaction when exposed to light, offers researchers a promising pathway for clean energy generation. Photocatalysis uses solar energy under environmentally friendly conditions with minimal pollution. But it has not been adopted for more widespread applications because of its low catalytic efficiency.
In this review, the team discusses advanced strategies to improve photocatalytic performance by modulating photocatalytic supports and refining co-catalysts. They highlight techniques, such as hydrogenation and extrinsic doping of photocatalytic supports, for their ability to broaden light absorption and prolong electron lifetimes. They also discuss the strategic design of co-catalysts, including the use of nanoclusters and atomically dispersed catalysts, that can optimize charge carrier potential and improve atomic utilization efficiency.
As concern about global warming grows, the need for sustainable and eco-friendly development has increased. In sustainable development, researchers' main goal is to reduce emissions of harmful pollutants such as carbon dioxide, carbon monoxide, nitrogen oxides, sulfur oxides, and volatile organic compounds. Researchers know that conventional fossil fuel-based development significantly contributes to these emissions, resulting in the release of more than 35 billion tons of carbon dioxide annually. That amount is continuously increasing. With its ability to harness limitless, clean solar energy, photocatalysis offer strong potential for researchers pursuing sustainable development goals. Photocatalysis reaction typically occurs under environmentally friendly conditions, such as in water, in air, and at room temperature. "These characteristics make photocatalysis more advantageous than electrocatalysis or thermocatalysis, as it results in lower or ideally zero pollutant emissions during reactions or energy production," said Chan Woo Lee from Seoul National University.
Although photocatalysis holds great potential for sustainable development, it often shows
lower catalytic efficiency than thermocatalysis or electrocatalysis. As a result, extensive research has been directed at improving photocatalytic performance by addressing these key challenges.
The team introduces actual cases, discussing how synthetic approaches are applied to develop high-performance photocatalysts. These can be effectively used in clean energy production reactions, such as carbon dioxide reduction reaction and hydrogen generation through the photoreforming of non-recyclable plastics. Photoreforming uses sunlight and a catalyst to produce hydrogen fuel from plastic waste.
"Developing high-performance photocatalysts hinges on strategically addressing key
challenges through precise synthetic approaches," said Lee. Modulating photocatalytic supports enhances light absorption and overcomes the limitations of pristine materials. The tailored design of co-catalysts becomes crucial to tackle the short-lived nature of photo-generated charge carriers and optimize potential energy for targeted chemical reactions. These strategies pave the way for groundbreaking advancements in photocatalytic performance.
Even though research has advanced photocatalytic performance, the energy efficiency of photocatalytic reactions is still lower than electro- or thermocatalytic energy conversion methods. Further progress in absolute efficiency is essential for practical application on a large scale. To achieve this, the team notes that several strategies must be explored.
Integrating photocatalytic support modulation with co-catalyst tuning shows potential. Additionally, developing a catalyst system that features two distinct metal atoms as co-catalysts could potentially enhance performance and reveal novel catalytic pathways. There also needs to be parallel development of scalable photocatalytic reaction platforms.
Electrochemical and thermochemical processes have well-established and scalable systems. But photocatalytic reactions lack standardized systems suitable for industrial application. Although panel-type reactors have been the primary option for large-scale photocatalytic reactions, they too face challenges. Recently, however, floatable photocatalytic reaction platforms have emerged, offering a more viable path toward large-scale implementation. However, the team notes, there remains a great opportunity to invent more efficient reaction platforms with new concepts.
"Although we overview limited cases of photocatalytic clean energy productions, such as
carbon dioxide reduction reaction and hydrogen gas generation via the photoreforming of plastic wastes, there are various reactions that can be explored with photochemical transformation," said Lee. For example, lignocellulose, the most available biomass in the earth, can be consumed for reactants of hydrogen gas generation through photocatalytic process. Taking it a step further, it is even possible to develop high-performance photocatalysts for producing important industrial chemicals, such as hydrogen peroxide and propylene oxide, by blending synthetic approaches guided for photocatalysts and knowledge gained from electrochemical systems.
The research is funded by the Institute for Basic Science.
The research team includes Chan Woo Lee, Jeong Hyun Kim, Megalamane S. Bootharaju, and Taeghwan Hyeon, who work at the Institute for Basic Science, Seoul, Korea, and the Seoul National University; and Byoung Hoon Lee, who works at the Institute for Basic Science, Seoul, Korea, and Korea University.
About Carbon Future
Carbon Future is an open access, peer-reviewed and international interdisciplinary journal, published by Tsinghua University Press and exclusively available via SciOpen . Carbon Future reports carbon-related materials and processes, including catalysis, energy conversion and storage, as well as low carbon emission process and engineering. Carbon Future will publish Research Articles, Reviews, Minireviews, Highlights, Perspectives, and News and Views from all aspects concerned with carbon. Carbon Future will publish articles that focus on, but not limited to, the following areas: carbon-related or -derived materials, carbon-related catalysis and fundamentals, low carbon-related energy conversion and storage, low carbon emission chemical processes.
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