Highly selective CO2 electroreduction to CO by the synergy between Ni–N–C and encapsulated Ni nanoparticles

Efficient catalysts are highly desirable for the selective electrochemical CO2 reduction reaction (CO2RR). Ni single-atom catalysts are known as promising CO2RR 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 CO2RR. The CO faradaic efficiency (FECO) reached 96.4% at −0.9 V and retained over 90% in a wide potential window. More importantly, FECO values of over 94% have been obtained from −50 to −170 mA cm−2 with a peak FECO 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 CO2RR catalysts.