Biochar has often been praised as a "black gold" for sustainable agriculture, pollution control, and carbon storage. Yet despite its promise, its wider use has been limited by a practical challenge: compared with materials such as activated carbon, graphene, and carbon nanotubes, biochar often has lower surface area and electrical conductivity. Expensive post-treatment methods can improve its performance, but they may also increase cost, energy use, and secondary pollution.
A new review published in Biochar argues that the future of biochar may depend less on forcing it to imitate advanced carbon materials and more on using what makes it naturally special: its ability to exchange, store, and transfer electrons.
The review, titled "Driving biochar applications via intrinsic redox superiority: electron transfer mechanisms, quantification, aging effects, and design strategies," was authored by Shasha Li, Zimeng Zhang, Yanling Ren, Fan Lü, Xiaoying Hu, Zhenhan Duan, Lili Yang, Jianwei Du, Pinjing He, Mingyang Zhang, and Yong Wen.
"Biochar is not simply a porous adsorbent. It is an active participant in electron transfer processes," said corresponding author Mingyang Zhang. "By understanding and tuning its intrinsic redox properties, we can design more sustainable biochar materials for pollutant degradation, microbial processes, energy recovery, and long-term environmental use."
At the center of the review is the concept of electron exchange capacity, or EEC, which includes both electron-donating capacity and electron-accepting capacity. These properties arise from redox-active moieties, including oxygen-containing groups, nitrogen-containing groups, persistent free radicals, and redox-active minerals embedded within the biochar structure.
The authors explain that these redox-active sites can allow biochar to act like an electron shuttle or electron buffer. In environmental systems, this can help microorganisms transfer electrons more efficiently, accelerate the degradation of organic pollutants, support anaerobic digestion, and assist reactions involved in energy recovery and carbon dioxide conversion.
Importantly, the review shows that biochar's performance cannot be explained by conductivity alone. In some cases, biochar with lower conductivity can outperform highly conductive materials because its redox-active sites can both transfer and temporarily store electrons. This gives biochar a functional advantage in stressed or electron-limited environments.
The review also highlights major scientific challenges. One key issue is accessibility. Even if biochar contains many redox-active groups, not all of them are available to microorganisms, contaminants, oxidants, or reductants. Their effectiveness depends on where they are located, whether they can be reached within pores or surfaces, and whether their redox potential matches the reaction partners.
Another challenge is measurement. The authors compare chemical, electrochemical, and microbiological methods for quantifying electron exchange capacity, noting that each has strengths and limitations. Differences in redox reagents, pH, adsorption effects, mediators, equilibration time, and microbial accessibility can lead to different results. The review calls for more standardized protocols to improve comparison across studies.
The authors also emphasize the importance of environmental aging. Once biochar enters soil, water, or waste-treatment systems, it interacts with oxygen, minerals, organic matter, and microbes. These processes may either enhance or weaken its redox properties over time, making long-term monitoring essential for real-world applications.
Looking ahead, the review proposes a shift toward targeted, low-cost, and low-pollution design strategies. Rather than relying heavily on chemical modification after production, future biochar engineering could regulate feedstock composition, co-pyrolysis conditions, mineral elements, and structural features. The authors also point to data-driven and multi-objective optimization approaches as promising tools for balancing performance, cost, and environmental safety.
"The key is to design biochar around its own strengths, not just copy other carbon materials," said corresponding author Yong Wen. "If we can identify, visualize, quantify, and preserve the right redox-active structures, biochar can become a more competitive and sustainable material for large-scale environmental solutions."
By reframing biochar as a naturally redox-active material, the review offers a roadmap for improving its role in pollution control, soil remediation, carbon management, and renewable energy systems.
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Journal Reference: Li, S., Zhang, Z., Ren, Y. et al. Driving biochar applications via intrinsic redox superiority: electron transfer mechanisms, quantification, aging effects, and design strategies. Biochar 8, 87 (2026).
https://doi.org/10.1007/s42773-026-00593-0
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About Biochar
Biochar (e-ISSN: 2524-7867) is the first journal dedicated exclusively to biochar research, spanning agronomy, environmental science, and materials science. It publishes original studies on biochar production, processing, and applications—such as bioenergy, environmental remediation, soil enhancement, climate mitigation, water treatment, and sustainability analysis. The journal serves as an innovative and professional platform for global researchers to share advances in this rapidly expanding field.
