Promising triazole molecular catalyst enables efficient electroreduction of carbon dioxide to methane

The efficient conversion of carbon dioxide (CO₂) – one of the main compounds contributing to climate change – into useful fuels and chemicals is a long-sought research goal. Recent studies have introduced various catalysts that could be used to initiate so-called electrochemical CO.₂ reduction reaction in electrolyzers (i.e. devices that drive specific chemical reactions using electricity).

The CO₂ The reduction reaction is the chemical process by which CO₂ the molecules are reduced, eventually forming other chemicals or fuels. Most catalysts previously used to initiate this reaction in electrolyzers are metallic, such as copper, silver and gold.

However, metal-based catalysts often have limited adaptability, meaning there is a need to harness them to precisely reduce CO₂ in specific chemicals can be difficult. Some studies have thus evaluated the potential of alternative non-metallic catalysts to convert CO₂ into desirable fuels and chemicals.

Researchers from the Chinese University of Hong Kong, the University of Auckland and National Yang Ming Chiao Tung University recently presented a promising new triazole molecular catalyst for the efficient electrochemical reduction of CO₂ in methane (CH₄). A preliminary system using this catalyst, presented in an article published in Natural energyproven to reliably convert CO₂ in CH₄presenting both good efficiency and a good rotation frequency.

“Organic molecular catalysts, which are more precise than metal catalysts, are still unable to catalyze CO₂ to hydrocarbons under industrially relevant current densities for long-term operation, and the catalytic mechanism is still elusive,” Zhanyou Xu, Ruihu Lu and colleagues wrote in their paper. “We report 3,5-diamino-1 ,2,4- triazole membrane electrode assemblies for CO₂-to-CH₄ conversion with a faradic efficiency of (52 ± 4)% and a rotation frequency of 23,060 h⁻¹ at 250 mA cm⁻²“.

Researchers have imagined a first CO reduction system₂ using their triazole molecule catalyst and explored its performance in a series of tests, where they ran it at a current of 10 A for 10 hours of electrolysis. Their findings were very promising and gave them valuable insight into the process by which their system converts CO₂ in CH₄.

“Our mechanistic studies suggest that CO₂ the reduction at the 3,5-diamino-1,2,4-triazole electrode takes place via *CO₂–*COOH–*C(OH)₂–*COH to produce CH₄ due to the spatially distributed active sites and the appropriate energy level of the molecular orbitals,” Xu, Lu and colleagues wrote. “A pilot system operated under a total current of 10 A (current density = 123 mA cm⁻²) for 10 h is capable of producing CH₄ at a rate of 23.0 mmol h⁻¹“.

Overall, the results of this recent study highlight the potential of triazole molecular catalysts to enable scalable and selective CO electroreduction.₂. The promising catalyst they identified, 3,5-diamino-1,2,4-triazole (DAT), could soon be further studied and evaluated by other research teams, or could inspire the design of similar catalysts to convert CO₂ into other useful chemicals.

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