Browsing by Author "Kannan, Palanisamy"

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    High-valence tungsten doping induces lattice expansion in Mo–Cu metal-organic framework-derived metal oxide-carbon composite (W@Mo–Cu MOF-MOCC) for enhanced urea electrooxidation catalysis
    (Elsevier Ltd, 2025) Linkov, Vladimir; Zheng, Yibing; Kannan, Palanisamy
    In this work, we report W@Mo–Cu metal-organic framework-derived metal oxide-carbon composite (W@Mo–Cu MOF-MOCC) as promising catalysts for the urea oxidation reaction (UOR), achieving a high current density of 10.0 mA cm−2 at 1.38 V. This performance surpasses that of Mo–Cu MOF-MOCC (10.0 mA cm−2 at 1.53 V), Cu-MOF-MOCC (10.0 mA cm−2 at 1.60 V), and Mo-MOF-MOCC (5.0 mA cm−2 at 1.68 V). Moreover, W@Mo–Cu MOF-MOCC exhibit a lower onset potential of 1.12 V vs. RHE and the lowest Tafel slope of 77.8 mV dec−1, indicating excellent catalytic activity comparable to various Ni-based catalysts. The enhanced UOR performance is attributed to three key factors: (i) doping with a high-valence metal (W) induces lattice expansion evidenced by the formation of (110) planes-in the Mo–Cu MOF-MOCC catalyst, which modulates the nanocrystalline interface, enhances grain boundary dynamics, and promotes the generation of active MoOOH species for efficient UOR (ii) the unique chicken-piece-like globular nanostructure provides a higher surface area (148.9 m2/g) and more active sites than other morphologies (e.g., rod-like Cu-MOF-MOCC, oval-like Mo-MOF-MOCC, and polyhedral Mo–Cu MOF-MOCC); and (iii) the synergistic interaction between W and the Mo–Cu interface enhances urea adsorption and oxidation at the catalyst surface. For practicality, a urine-mediated electrolysis cell was also developed, achieving a UOR current density of 10.0 mA cm−2 at 1.37 V in urine-containing wastewater, which is over 200 mV lower than in urea-free electrolyte. Furthermore, similar performance was observed in a 1.0 M NaOH + seawater electrolyte, reaching 10.0 mA cm−2 at 1.38 V. These findings demonstrate the potential of W@Mo–Cu MOF-MOCC as multi-functional, noble-metal-free, and Ni-free catalysts for green energy production and sustainable wastewater treatment, offering promising implications for environmental safety and resource recovery.