Upcycling waste protein and heavy metal into single-atom catalytic gas diffusion electrode for CO₂ reduction

Highlights

	● The utilization of waste proteins and heavy metals for CO2 to CO conversion.
	● Proteins atomically disperse Ni onto a gas diffusion electrode (GDE).
	● Porous structure of GDE is capable of CO2 diffusion and storage.
	● N element is crucial to synthesize efficient Ni single atom catalysts (Ni SACs).
	● GDE is composed of nanofibers with uniformly dispersed Ni SACs.

Abstract

The global production of organic wastes and heavy metals (HMs) poses significant environmental risks, along with considerable carbon emissions from waste decomposition. This highlights the significance of synergistic management of both wastes and CO₂, which is a vital strategy for mitigating environmental pollution and climate change. Herein, we employed waste protein from wastewater produced during soybean peptide (SP) processing as a carbon matrix to anchor HMs Ni from electroplating wastewater. This mixture was electrospun into a gas diffusion electrode (GDE). This unique GDE design eliminates the need for a separate gas diffusion layer (GDL) and simplifies catalyst production. This versatile GDE consists of nanofibers with uniformly dispersed Ni single atom catalysts (SACs) on the fiber surface. Therefore, boasts a porous structure that facilitates CO₂ diffusion and storage. The homogeneous distribution of Ni SACs within the GDE fosters high activity in the electrochemical conversion of CO₂ to CO. At 50 mA/cm² and 2.5 V cell voltage, Ni SACs achieved an excellent Faradaic efficiency of 81%−98% in a membrane electrode assembly (MEA). This technique holds a promise in achieving the collaborative management of carbon mitigation and wastes recovery.

Graphical abstract

Keywords

Waste protein / Heavy metal wastewater / Ni single atom / Electrospinning / Gas diffusion electrode / CO₂ reduction

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Conflict of Interests

Lu Lu is a youth editorial board member of Frontiers of Environmental Science & Engineering. The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

Acknowledgements

This work was financially supported by the National Natural Science Foundation of China (No. 22176046), the Science Fund for Creative Research Groups of the National Natural Science Foundation of China (No. 52321005), the Shenzhen Science and Technology Program (Nos. KQTD20190929172630447, JCYJ20210324124209025, and GXWD20220811173949005), and the Natural Science Foundation of Guangdong Province (No. 2022A1515012016).

Electronic Supplementary Material

Supplementary material is available in the online version of this article at https://doi.org/10.1007/s11783-025-1974-y and is accessible for authorized users.

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