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

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 (H-2). The system has a positively shifted onset potential of hydrogen evolution reaction (HER) by 0.4V compared to a typical HER under alkaline conditions and facile HER kinetics with low Tafel slope of 34 mVdec @ 1. The Al-CO2 system has a maximum power density of 125 mWcm @ 2 which is the highest value among CO2 utilization electrochemical system.