Electrochemical CO2 Reduction at Surface Modified Silver Nanoparticles

CO2 capture and transformation into chemical fuels presents a useful carbon-neutral energy source to curb the effects of global warming if the electrocatalyst used is highly active, exhibits sufficient product selectivity, and is energetically efficient. Metal nanoparticles (NPs) have emerged as a promising class of catalysts for the electrochemical CO2 reduction reaction (CO2RR) and their product selectivity are expected to be further improved through surface modification with different ligands. The primary objective of this work is to compare the use of Scanning Electrochemical Microscopy (SECM) and Rotating Ring Disk Electrode (RRDE) to study CO2 reduction at silver nanoparticles (Ag NPs) modified with amino acids (cysteine and tryptophan) and Ag NPs synthesized by a citrate reduction method. RRDE studies showed the onset potential for CO2RR was earlier for both the Ag NPs with cysteine and Ag NPs with tryptophan than those with citrate. SECM showed earlier onset potentials for CO2RR than the RRDE experiment for every type of Ag NP as well as higher sensitivity in detecting the major CO2RR products such as formate and CO. SECM also showed less hydrogen formation for the Ag NPs with cysteine and Ag NPs with tryptophan.