Sustainability Perspective-Oriented Synthetic Strategy for Zinc Single-Atom Catalysts Boosting Electrocatalytic Reduction of Carbon Dioxide and Oxygen

Green and sustainable electrochemical conversion and storage devices possess the nature to repress a negative effect on sustainability during energy conversion and storage. However, the sustainability of devices' components themselves (e.g., raw material abundance, eco-friendliness, and recycling) is often ignored, which may damage the environment and limit devices' practical applicability. Herein, guided by the concept of sustainability, a sustainable strategy is reported to synthesize the very cheap single zinc atoms dispersed on nitrogen-doped hierarchically porous carbon (SA-Zn-NHPC) with minimized environmental expense by employing abundant natural apples, natural egg whites, and relatively non-toxic ZnCl2 as raw materials. Theory calculations and experiments prove that Zn-N4 within SA-Zn-NHPC is responsible for superior CO2 reduction reaction (CO2RR) activity with high CO Faradaic efficiency (96%) at low overpotential (0.33 V) and outstanding O2 reduction reaction (ORR) activity with high half-wave potential (0.87 V) and high onset potential (1.00 V), which are among the best performance of single-atom catalysts. Additionally, remarkable activity and high stability of SA-Zn-NHPC for CO2RR and ORR as well as ultralow feedstock cost would render the recycling procedure for end-of-life catalysts (e.g., Pt within fuel cells) unrequired. The sustainability perspective-oriented strategy will bring major advances in both economical energy cost and environment protection.