N2 to NH3 by 3MCs: Electrochemical Dinitrogen Reduction by Trimetallic Catalysts

The synergistic effects among the metals are often responsible for the increased activity, selectivity, and stability, hence, the impressive catalytic activity over monometallic by bimetallic counterparts has been reported.

Trimetallic catalysts (3MCs) have been successfully used for different reactions, however, there are few reports on 3MCs for electrocatalytic dinitrogen reduction (NR).

Most of the catalysts for NR suffer from slow mass and electron transport, low dinitrogen affinity, and reduced activity, therefore we proposed multifunctional 3MCs anchored on a suitable substrate to solve these problems.

This project will develop a series of 3MCs for NR on carbon electrode denoted M-D1-D2 (where M (Metal)= Co and Cu) (-D1 - D2 ((Doping 1-Doping 2) = Zn-Li, Zn-Cs, Zn-La, etc.) to boost selectivity and activity of NR in a 0.1 M phosphate buffer aqueous solution compared and reach FEs of over 50% and high ammonium yields to fulfill requirements for industrialization.

Dinitrogen is a weak Lewis base; hence it is rational to create a Lewis acid catalytic site to give preference for the binding of dinitrogen over proton.

Therefore, we are going to use Li, Cs, Zn, and La as Lewis acid dopants with different affinity (low, moderate, and strong) toward NR.

The change of the charge at the surface of the electrode at the atomic level is going to be confirmed by XANES and EXAFS. To further adjust dinitrogen affinity, pyridine derivatives as the heteroatom dopant, (e.g. Pyridine, 4-tert-Butylpyridine, etc.)) will be used.

The heteroatoms interact with the pi star orbital of the dinitrogen by electron-donating and increasing the absorption affinity. The change in affinity will be confirmed with dinitrogen temperature-programmed desorption (TPD) measurement. The mechanistic studies will be performed by state-of-the-art techniques of the highest active 3MC.

The result will feed back into the synthetic work to guide the optimization of electrochemical performance.