Metal-Free Bifunctional Ordered Mesoporous Carbon for Reversible Zn-CO₂ Batteries

The fabrication of Zn-CO₂ batteries is a promising technique for CO₂ fixation and energy storage. Herein, nitrogen-doped ordered mesoporous carbon (NOMC) is adopted as a bifunctional metal-free electrocatalyst for CO₂ reduction and oxygen evolution reaction in the near-neutral electrolyte. The ordered mesoporous structures and abundant N-dopings of NOMC facilitate the accessibility and utilization of the active sites, which endow NOMC with excellent electrocatalysis performance and outstanding stability. Especially, a nearly 100% CO Faradaic efficiency is achieved at an ultralow overpotential of 360 mV for CO₂ reduction. When constructed as an aqueous rechargeable Zn-CO₂ battery using NOMC as the cathode, it yields a high peak power density of 0.71 mW cm^-2 , a good cyclability of 300 cycles, and excellent energy efficiency of 52.8% at 1.0 mA cm^-2 .