Integrating Carbon-Coated Cu/Cu2O Nanoparticles with Biochars Enabled Efficient Capture and Electrocatalytic Reduction of CO2

Because the interfacial Cu0/Cu+ in Cu-based electrocatalyst promotes CO2 electroreduction activity, it would be highly desirable to physically separate Cu-based nanoparticles through coating shells and load them onto porous carriers. Herein, multilayered graphene-coated Cu (Cu@G) nanoparticles with tailorable core diameters (28.2–24.2 nm) and shell thicknesses (7.8–3.0 layers) were fabricated via lased ablation in liquid. A thin Cu2O layer was confirmed between the interface of the Cu core and the graphene shell, providing an interfacial Cu0/Cu+. Cu@G cross-linked biochars (Cu@G/Bs) with developed porosity (31.8–155.9 m2/g) were synthesized. Morphology, crystalline structure, porosity, and elemental chemical states of Cu@G and Cu@G/Bs were characterized. Cu@G/Bs captured CO2 with a maximum sorption capacity of 107.03 mg/g at 0 °C. Furthermore, 95.3–97.1% capture capacity remained after 10 cycles. Cu@G/Bs exhibited the most superior performance with 40.7% of FEC2H4 and 21.7 mA/cm2 of current density at −1.08 V vs. RHE, which was 1.7 and 2.7 times higher than Cu@G. Synergistic integration of developed porosity for efficient CO2 capture and the fast charge transfer rate of interfacial Cu2O/Cu enabled this improvement. Favorable long-term stability of the phase/structure and CO2 electroreduction activity were present. This work provides new insight for integrating Cu@G and a biochar platform to efficiently capture and electro-reduce CO2.