Bismuth Anchored on MWCNTs with Controlled Ultrafine\nNanosize Enables High-Efficient Electrochemical Reduction of Carbon\nDioxide to Formate Fuel

Abstract

Metal\nnanoparticles\nusually exhibit\nunique catalytic performance, while unfortunately,\nso far, the Bi nanoparticles (NPs) (<5 nm) have not been employed\nfor the electrochemical reduction of carbon dioxide (ECR-CO₂). Here, we report a facile and mild strategy to fabricate Bi nanocrystals\nin situ decorated on functionalized multiwalled carbon nanotubes (Bi\nNP@MWCNTs) as a high-performance catalyst for ECR-CO₂.\nThe transmission electron microscopy (TEM) images revealed that the\nBi NPs with an average particle size of 4.4 nm were uniformly supported\non the MWCNTs. The resulting Bi NP@MWCNTs exhibit much higher electrocatalytic\nactivity, Faradaic efficiency (FE), and current density than the Bi_blank catalyst toward CO₂ reduction to formate.\nAt −1.5 V versus SCE (saturated calomel reference electrode),\nthe maximum FE of 95.2% for formate was achieved on a Bi NP@MWCNT\ncatalyst with a current density of 10.7 mA cm⁻². MWCNTs play an important\nrole in the markedly enhanced activity for CO₂ reduction\nto formate on Bi NP@MWCNT catalysts. Besides, the formation of the\n*OCOH intermediate is considered as the rate-limiting step for CO₂ conversion to formate on Bi NP@MWCNT catalysts. The results\nindicate that the as-prepared Bi NP@MWCNT catalysts exhibit promising\npotential in the electrochemical reduction of CO₂ to fuels.