Built-in Electric Field-Induced Work Function Reduction in C-Co 3 O 4 for Efficient Electrochemical Nitrogen Reduction.

Co 3 O 4 is a highly selective catalyst for the electrochemical conversion of N 2 to NH 3 . However, the large work function (WF) of Co 3 O 4 leads to unsatisfactory activity. To address this issue, a strong built-in electric field (BIEF) was constructed in Co 3 O 4 by doping C atoms (C-Co 3 O 4 ) to reduce the WF for improving the electrocatalytic performance. C-Co 3 O 4 exhibited a remarkable NH 3 yield of 38.5 μg h -1 mg cat -1 and a promoted FE of 15.1% at -0.3 V vs RHE, which were 2.2 and 1.9 times higher than those of pure Co 3 O 4 , respectively. Kelvin probe force microscopy (KPFM), zeta potential, and ultraviolet photoelectron spectrometry (UPS) confirmed the formation of strong BIEF and WF reduction in C-Co 3 O 4 . Additionally, in situ Raman measurements and density functional theory (DFT) calculations revealed the relationship between BIEF and WF and provided insights into the reaction mechanism. Our work offers valuable guidance for the design and development of more efficient nitrogen reduction catalysts.