Efficient Electrocatalytic Reduction of Carbon Dioxide Using Supported Bimetallic Catalysts By Altering the Size and Structure of Nanoparticles

Abstract

Bimetallic nanoparticles of Au and Cu and the corresponding monometallics of each metal are prepared and supported on functionalized multiwalled carbon nanotubes (MWCNT). The supported bimetallic nanoparticles are dispersed uniformly on fiber carbon papers (CP). To evaluate and relate the performance of the reduction, tuning the size and structural properties of AuCu electrocatalyst are studied and investigated by incorporating polyvinylpyrrolidone (PVP) for electrochemical reduction (ECR) of CO2. Different amounts of PVP are applicable for each bimetallic and monometallic electrocatalysts (AuCu/MWCNT/CP, Au/MWCNT/CP and Cu/MWCNT/CP). The significant role of PVP on the atomic distribution of AuCu nanoparticles (NPs) and its particle size have been studied in advance. X-ray absorption near edge spectroscopy (XANES) and extended X-ray absorption fine structure (EXAFS) are key measurements to estimate the alloying extent of Au and Cu in the alloy including the coordination numbers of each metal. The electrocatalysts, which are prepared with PVP, have a better activity and selectivity compared to the bimetallic synthesized without PVP. The amount of PVP affects the structure and significantly minimizes the size of NPs that influences the activity and selectivity of products. At -0.91 V vs. RHE, the faradaic efficiency (FE%) of CO using AuCu/CNT (1.5 g PVP) was nearly 87%, but in the absence of PVP, the same test resulted in ~70%, indicating the effect of PVP in the product selectivity is shown clearly.