Preparation of Metal Amalgam Electrodes and Their Selective Electrocatalytic CO₂ Reduction for Formate Production

• Main Authors: Syed Asad Abbas, Seong-Hoon Kim, Hamza Saleem, Sung-Hee Ahn, Kwang-Deog Jung
• Format: Article
• Language: English
• Published: MDPI AG 2019-04-01
• Series: Catalysts
• Subjects: electrochemical CO₂ reduction; formate formation; Pd amalgam; metal amalgam electrodes
• Online Access: https://www.mdpi.com/2073-4344/9/4/367

Electrochemical CO₂ reduction to produce formate ions has studied for the sustainable carbon cycle. Mercury in the liquid state is known to be an active metallic component to selectively convert CO₂ to formate ions, but it is not scalable to use as an electrode in electrochemical CO₂ reduction. Therefore, scalable amalgam electrodes with different base metals are tested to produce formate by an electrochemical CO₂ reduction. The amalgam electrodes are prepared by the electrodeposition of Hg on the pre-electrodeposited Pd, Au, Pt and Cu nanoparticles on the glassy carbon. The formate faradaic efficiency with the Pd, Au, Pt and Cu is lower than 25%, while the one with the respective metal amalgams is higher than 50%. Pd amalgam among the tested samples shows the highest formate faradic efficiency and current density. The formate faradaic efficiency is recorded 85% at −2.1 V vs SCE and the formate current density is −6.9 mA cm^−2. It is concluded that Pd₂Hg₅ alloy on the Pd amalgam electrode is an active phase for formate production in the electrochemical CO₂ reduction.