Construction of Cobalt Porphyrin-Modified Cu₂O Nanowire Array as a Tandem Electrocatalyst for Enhanced CO₂ Reduction to C₂ Products.

Abstract

Here, the molecule-modified Cu-based array is first constructed as the self-supporting tandem catalyst for electrocatalytic CO₂ reduction reaction (CO₂RR) to C₂ products. The modification of cuprous oxide nanowire array on copper mesh (Cu₂O@CM) with cobalt(II) tetraphenylporphyrin (CoTPP) molecules is achieved via a simple liquid phase method. The systematical characterizations confirm that the formation of axial coordinated Co-O-Cu bond between Cu₂O and CoTPP can significantly promote the dispersion of CoTPP molecules on Cu₂O and the electrical properties of CoTPP-Cu₂O@CM heterojunction array. Consequently, as compared to Cu₂O@CM array, the optimized CoTPP-Cu₂O@CM sample as electrocatalyst can realize the 2.08-fold C₂ Faraday efficiency (73.2% vs 35.2%) and the 2.54-fold current density (‒52.9 vs ‒20.8 mA cm^-2) at ‒1.1 V versus RHE in an H-cell. The comprehensive performance is superior to most of the reported Cu-based materials in the H-cell. Further study reveals that the CoTPP adsorption on Cu₂O can restrain the hydrogen evolution reaction, improve the coverage of ^*CO intermediate, and maintain the existence of Cu(I) at low potential.