Built-in Electric Field-Induced Work Function Reduction in C-Co₃O₄ for Efficient Electrochemical Nitrogen Reduction

Area of Science:

• Electrochemistry
• Materials Science
• Catalysis

Background:

• Cobalt oxide (Co3O4) shows high selectivity for electrochemical nitrogen (N2) to ammonia (NH3) conversion.
• The high work function (WF) of Co3O4 limits its catalytic activity.

Purpose of the Study:

• To enhance the electrocatalytic performance of Co3O4 for N2 reduction.
• To reduce the work function (WF) of Co3O4 by introducing a strong built-in electric field (BIEF).

Main Methods:

• Doping Co3O4 with carbon atoms to create C-Co3O4.
• Utilizing Kelvin probe force microscopy (KPFM), zeta potential, and ultraviolet photoelectron spectrometry (UPS) to characterize BIEF and WF.
• Employing in situ Raman spectroscopy and density functional theory (DFT) calculations to investigate the reaction mechanism.

Main Results:

• C-Co3O4 demonstrated a 2.2 times higher NH3 yield (38.5 μg h-1 mgcat-1) compared to pure Co3O4.
• The Faradaic efficiency (FE) for NH3 production was promoted by 1.9 times (15.1%) with C-Co3O4 at -0.3 V vs RHE.
• Characterization techniques confirmed the formation of BIEF and reduced WF in C-Co3O4.

Conclusions:

• Constructing a BIEF by doping C atoms effectively reduces the WF of Co3O4, enhancing its electrocatalytic activity for N2 reduction.
• The study provides insights into the mechanism of BIEF and WF effects on N2 electroreduction.
• This work offers a valuable strategy for designing advanced nitrogen reduction catalysts.