Highly selective CO 2 electroreduction to CO by the synergy between Ni-N-C and encapsulated Ni nanoparticles.

Efficient catalysts are highly desirable for the selective electrochemical CO 2 reduction reaction (CO 2 RR). Ni single-atom catalysts are known as promising CO 2 RR catalysts, while Ni NPs are expected to catalyze the competing HER. In this work, we have modified the Ni NPs by encapsulating them into porous Ni-N-C nanosheets (Ni@Ni-N-C), to boost the synergy between Ni NPs and dispersed Ni-N species towards CO 2 RR. The CO faradaic efficiency (FE CO ) reached 96.4% at -0.9 V and retained over 90% in a wide potential window. More importantly, FE CO values of over 94% have been obtained from -50 to -170 mA cm -2 with a peak FE CO of 99% in a flow cell. Our work demonstrates that the surface modification of Ni NPs can inhibit the unexpected HER and activate the surface sites, offering a practical design strategy for CO 2 RR catalysts.