Superficial S atom optimized active sites in NiFe layered double hydroxides for electrocatalytic urea oxidation

The development of efficient strategies for wastewater remediation coupled with clean energy generation represents a major global challenge. In this context, the urea oxidation reaction (UOR) emerges as a highly promising approach, capable of simultaneously degrading urea-rich wastewater and enabling energy-efficient hydrogen production.

Traditionally, precious metals such as ruthenium, iridium, and rhodium have been employed for their superior UOR activity; however, their scarcity and high cost severely restrict large-scale applications. NiFe layered double hydroxides (NiFe-LDH) have emerged as a cost-effective alternative owing to their unique layered architecture. Nevertheless, in pristine NiFe-LDH, the strong binding of hydroxyl groups to iron sites impedes the formation of highly active nickel species, thereby elevating the onset potential. Furthermore, identifying and tracking these active sites at the molecular level during the UOR process remains a formidable challenge.

To address these limitations, a research team led by Prof. Zhen Zhou and Wei Ma (Zhengzhou University) designed a novel sulfur-doped NiFe-LDH (S-NiFe-LDH) electrocatalyst, optimizing the internal electronic structure by incorporating sulfur with low electronegativity. This strategic modification successfully shifts the catalytic active sites from conventional nickel and iron centers to high-valence nickel intermediates at substantially reduced applied potentials.

The incorporation of sulfur significantly lowers the thermodynamic barrier of the nickel active sites. It enhances the intrinsic activity and kinetics of urea decomposition by facilitating the formation of active Ni³⁺-O species through more facile dehydrogenation steps. Consequently, the S-NiFe-LDH catalyst exhibits excellent UOR performance, achieving a current density of 100 mA cm^-2 at an exceptionally low potential of 1.36 V, alongside remarkable long-term durability.

Ultimately, this work elucidates the real-time active sites during electrocatalysis and opens a new avenue for the electronic engineering of NiFe-based catalysts in UOR applications. This highly efficient and cost-effective strategy holds significant promise for advancing the practical implementation of urea-assisted hydrogen production toward a sustainable future. The results were published in Chinese Journal of Catalysis (DOI: 10.1016/S1872-2067(24)60168-3)

About the journal

Chinese Journal of Catalysis is co-sponsored by Dalian Institute of Chemical Physics, Chinese Academy of Sciences and Chinese Chemical Society, and it is currently published by Elsevier group. This monthly journal publishes in English timely contributions of original and rigorously reviewed manuscripts covering all areas of catalysis. The journal publishes Reviews, Accounts, Communications, Articles, Highlights, Perspectives, and Viewpoints of highly scientific values that help understanding and defining of new concepts in both fundamental issues and practical applications of catalysis. Chinese Journal of Catalysis ranks among the top six journals in Applied Chemistry with a current SCI impact factor of 17.7.

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