In the past century, the rapid acceleration of human industrial and urban activities has irreversibly altered the Earth’s atmosphere, prompting profound challenges such as climate change and deteriorating air quality. Anthropogenic emissions release a complex mixture of pollutants including particulate matter, volatile organic compounds (VOCs), nitrogen oxides (NOx), sulfur dioxide (SO2), and ammonia (NH3) into the troposphere. These pollutants interact under solar radiation to generate secondary pollutants, most noticeably ozone, which further exacerbate the environmental and health burdens faced by global populations. The formation of ozone from its precursors exhibits highly nonlinear chemistry, complicating mitigation efforts aimed at improving ambient air quality.
Governments around the world have enacted stringent emission regulations and adopted air quality standards to combat these pressing issues. Despite these policy interventions, challenges remain especially in rapidly developing regions where ozone pollution persists at alarming levels and particulate matter control is incomplete. The simultaneous management of ozone precursor emissions and particulate matter is essential but not trivial; significant reductions in VOC emissions, for instance, are notoriously difficult to achieve swiftly due to their diverse sources and complex atmospheric behavior. This reality necessitates innovative and effective air pollution control technologies that can operate in real-world urban settings.
Emerging at the forefront of advanced environmental technologies, researchers led by Hong He at the Chinese Academy of Sciences have systematically reviewed the potential of next-generation catalytic strategies to directly remove airborne pollutants. Their comprehensive study focuses primarily on photocatalysis and ambient temperature catalysis, highlighting these as promising routes for real-time atmospheric purification. Published in the Journal of Environmental Sciences in October 2025, this work synthesizes recent scientific advancements and proposes a visionary framework to revolutionize urban air quality management.
Photocatalysis is a process where light energy, typically ultraviolet or visible, excites semiconductor catalysts producing electron−hole pairs. These charge carriers migrate to the catalyst’s surface and initiate redox reactions that degrade adsorbed pollutants, including VOCs and nitrogen oxides, into less harmful compounds. This green approach has already found some practical applications in Japan and parts of Europe, demonstrating its viability. Nevertheless, challenges such as catalyst deactivation, economic feasibility, and integration within engineered structures remain to be overcome before widespread deployment.
Complementing photocatalysis, ambient temperature catalysis involves non-photocatalytic oxidation methods to decompose pollutants at standard urban environmental conditions without the need for external energy input. Catalysts such as TiO2-supported noble metals have proven effective for formaldehyde removal, while NiFe-layered double hydroxides show potential in ozone decomposition. These materials catalyze reactions that convert toxic air pollutants directly into benign products like water, carbon dioxide, and oxygen, offering an energy-efficient alternative or supplemental technique for air purification.
Expanding upon these catalytic advances, the research team introduces a groundbreaking conceptual design termed the “Environmental Catalytic City.” This visionary model entails coating urban infrastructure—building facades, road surfaces, vehicle radiators—with durable, efficient catalytic materials capable of passively purifying low-concentration pollutants present in ambient air. Such an integrated cityscape would function as a large-scale catalytic reactor, continuously mitigating air pollution without additional energy expenditure. This synergistic urban self-purification holds the promise of reducing pollutant concentrations and improving public health sustainably.
The concept leverages the ubiquity of urban surfaces exposed to atmospheric pollutants, transforming them into active purification agents. It presents a paradigm shift from traditional point-source emission controls towards extensive, distributed environmental remediation. The deployment of stable, cost-effective catalysts on various city surfaces would harness naturally occurring sunlight and ambient conditions to drive pollutant degradation—a bold innovation that could redefine the nexus between urban planning and air quality management.
Despite the immense promise, significant scientific and engineering hurdles must be addressed to realize the Environmental Catalytic City vision. Material scientists must innovate catalysts with enhanced longevity, resistance to environmental fouling, and activity under diverse climatic conditions. Economical synthesis routes and scalable coating technologies will be critical to widespread adoption. Furthermore, multidisciplinary collaboration among atmospheric chemists, urban engineers, and policymakers is essential to integrate these catalytic systems effectively into urban environments.
Hong He emphasizes the urgency and optimism surrounding this emerging field, underscoring the nonlinear challenges posed by ozone and the limitations of precursor emission reductions alone. The direct atmospheric purification afforded by catalytic technologies could act as an indispensable booster in achieving cleaner urban air. Future scientific endeavors must prioritize developing low-cost catalytic materials able to efficiently degrade ozone and a broad spectrum of co-existing pollutants, thus enhancing the feasibility and impact of the Environmental Catalytic City framework.
This research also aligns closely with global sustainable development goals by addressing air pollution—a critical environmental risk factor globally linked to millions of premature deaths annually. By enabling cities to autonomously cleanse their ambient air, catalytic urban surfaces could significantly reduce public health burdens associated with respiratory and cardiovascular diseases. Additionally, these advances introduce a novel environmental engineering paradigm that addresses air quality and climate resilience concurrently.
While still in nascent stages, ongoing pilot studies and laboratory validations have begun demonstrating the practical applicability of catalytic coatings under real atmospheric conditions. Lessons learned from these pioneering implementations will inform optimization strategies and facilitate cross-disciplinary adoption. The integration of such catalytic solutions within existing urban infrastructure could transform policy approaches, bridging scientific innovation with tangible societal benefits in air quality management.
In sum, the comprehensive review by Hong He and colleagues outlines a compelling scientific and technological pathway towards a catalytic-enabled urban future. By shifting focus from emission reduction alone to active atmospheric remediation, this research advocates for an impactful new engine powering air pollution control. With continued investment and collaborative innovation, the vision of an Environmental Catalytic City providing sustainable, energy-neutral atmospheric purification stands poised to become a hallmark of 21st-century environmental stewardship.
Subject of Research:
Article Title: Environmental catalytic city: New engine for air pollution control
News Publication Date: 1 October 2025
Web References: https://doi.org/10.1016/j.jes.2025.02.019
References: DOI: 10.1016/j.jes.2025.02.019
Image Credits: barnyz from Flickr
Keywords: Environmental sciences, Air pollution, Atmospheric science, Climate change, Sustainable development, Environmental engineering, Chemistry, Nanotechnology, Materials science, Pollution control
