Volatile organic fatty acids (VFAs) are widely available and easily accessible renewable substrates obtained through waste and biomass fermentation. These VFAs serve as excellent candidates for upgrading into carbon-neutral biofuels, and Kolbe electrolysis offers a promising approach for their conversion in an aqueous environment.

Although platinum has traditionally received attention for its high efficiency and stability in Kolbe electrolysis, its large-scale application is hindered by its scarcity and high cost. To address this challenge, Jason Chun-Ho Lam, Wang Chong, and colleagues, City University of Hong Kong, have developed an amorphous RuO₂ (a-RuO₂) catalyst with oxygen vacancies using a hydrothermal method (picturd below). This novel catalyst demonstrates comparable electrocatalytic performance to platinum.

The team evaluated the catalyst’s effectiveness using hexanoic acid (C₆H₁₂O₂) as a model substrate, successfully producing decane (C₁₀H₁₂) through selective decarboxylative condensation. Notably, the researchers observed that the a-RuO₂ catalyst showed significantly larger electrochemically active surface areas compared to standard crystalline RuO₂, resulting in improved electrocatalytic activity.

Furthermore, this transformative approach can also be extended to other organic fatty acids such as heptanoic acid or octanoic acid. Cost-performance analysis of the electrocatalyst revealed that the use of a Ru-based catalyst is significantly cheaper than other known precious metals, including Pt, Ir, and Pd. These findings present a promising alternative to platinum catalysts, offering improved performance and addressing the limitations associated with their scarcity and cost.

• Selective Kolbe Electrolysis of Medium Size Carboxylic Acid to Alkane Dimer in an Aqueous Environment with an Amorphous RuO₂ Catalyst,
  Lam, Chong Wang, Kaixin Liu, Yangxin Jin, Shuquan Huang, Jason Chun-Ho Lam,
  ChemSusChem 2023.
  https://doi.org/10.1002/cssc.202300222