Highly Efficient CO₂ Utilization via Aqueous Zinc– or Aluminum–CO₂ Systems for Hydrogen Gas Evolution and Electricity Production

Abstract

Atmospheric carbon dioxide (CO₂ ) has increased from 278 to 408 parts per million (ppm) over the industrial period and has critically impacted climate change. In response to this crisis, carbon capture, utilization, and storage/sequestration technologies have been studied. So far, however, the economic feasibility of the existing conversion technologies is still inadequate owing to sluggish CO₂ conversion. Herein, we report an aqueous zinc- and aluminum-CO₂ system that utilizes acidity from spontaneous dissolution of CO₂ in aqueous solution to generate electrical energy and hydrogen (H₂ ). The system has a positively shifted onset potential of hydrogen evolution reaction (HER) by 0.4 V compared to a typical HER under alkaline conditions and facile HER kinetics with low Tafel slope of 34 mV dec^-1 . The Al-CO₂ system has a maximum power density of 125 mW cm^-2 which is the highest value among CO₂ utilization electrochemical system.