Improving NiNX and pyridinic N active sites with space-confined pyrolysis for effective CO2 electroreduction
Zhaozhao Zhu, Li Zhao, Junjie Wang, Rong Li, Haiyuan Chen, Yulan Li, Jun Song Chen, Rui Wu, Zidong Wei
Abstract
Even though various nickel–nitrogen–carbon (Ni-N-C) combinations are prospective low-cost catalysts for the CO2 electroreduction reaction (CO2RR), which is one avenue for attaining carbon neutrality, the detailed role of different N species has hardly been investigated. Here, we report a hollow porous N-doped carbon nanofiber with NiNX-pyridinic N active species (denoted as h-Ni-N-C) developed using a facile electrospinning and SiO2 space-confined pyrolysis strategy. The NiNX-pyridinic N species are facilely generated during the pyrolysis process, giving rise to enhanced activity and selectivity for the CO2RR. The optimized h-Ni-N-C exhibits a high CO Faradaic efficiency of 91.3% and a large current density of −15.1 mA cm−2 at −0.75 V versus reversible hydrogen electrode in an H-cell. Density functional theory (DFT) results show that NiN4-pyridinic N species demonstrate a lower free energy for the catalyst's rate-determining step than isolated NiN4 and pyridinic N species, without affecting the desorption of CO∗ intermediate.