Electrochemical CO2 and CO Reduction with Size-Selected Nanoparticles

Abstract

The development of efficient and selective catalysts for CO2 reduction (CO2R) is crucial for advancing the field of renewable energy and mitigating climate change. However, designing such catalysts is challenging due to the complexity of the CO2R process and the need for accurate modeling of catalyst behavior. Here, we present a novel experimental methodology that aims to bridge the gap between theoretical predictions and experimental observations to overcome these challenges.To obtain the intrinsic activity and selectivity of CO2R catalysts, we deposited gas phase size-selected gold and copper nanoparticles on flat surfaces (glassy carbon) using magnetron sputtering. These nanoparticles were selected within an extremely low size range (around 0.1 nm) by using a Time-Of-Flight (TOF) mass filter, and deposited at very low loadings (less than 0.5 µg/cm2) to avoid aggregation. We then used a chip-based electrochemical mass spectrometry (EC-MS) setup, with approx. 8µL of stagnant electrolyte, for electrochemical test of the catalysts under operando conditions with a high degree of sensitivity.Our findings reveal a non-linear relationship between the size of gold and copper nanoparticles and their selectivity for C+ products. Surprisingly, we found that both compositions exhibited an optimum size for C+ selectivity, which was not the largest size. By combining microscopy data with EC-MS results, we gained new insights into the intrinsic activity of size-selected nanoparticles and the factors that influence their selectivity.Our methodology offers a promising approach for designing product-selective catalysts for CO2R. By defining experimental model systems, we were able to obtain the intrinsic activity and selectivity of these catalysts with reduced influence from external conditions. Our research makes a significant contribution to the development of sustainable energy solutions by providing experimental data that can inform theoretical models and guide the design of more efficient and selective CO2R catalysts.