# In-situ grafting of cobalt phthalocyanine on gas diffusion electrodes enables ampere-level CO2 reduction

## TL;DR

A new method attaches cobalt phthalocyanine to gas diffusion electrodes, enabling efficient and stable CO2 reduction at high current densities.

## Contribution

A polypyrrole-mediated electro-polymerization strategy enables covalent grafting of pristine molecular catalysts onto GDEs.

## Key findings

- The CoPc/ppy/GDE electrode achieved stable operation for 120 h at 500 mA cm−2 and 50 h at 1 A cm−2.
- The system reached a solar-to-CO efficiency of 19.2% when coupled with a triple-junction solar cell.

## Abstract

Immobilizing molecular catalysts onto gas diffusion electrodes (GDEs) through covalent bonds provides a strategy to circumvent their issues of aggregation, detachment and poor conductivity during CO2 electrolysis. However, this approach has been limited to catalysts equipped with specially designed functional groups, and directly covalent grafting of pristine molecular catalysts onto GDEs remains a formidable challenge. Herein, using pristine cobalt phthalocyanine (CoPc) as a model catalyst, we propose a polypyrrole (ppy) mediated electro-polymerization strategy that creates robust C–C bonds between GDEs and pristine CoPc. In this scheme, ppy acts as both the conductive linker and scaffold for pristine CoPc, and its electron donation effects further enhances the CO2 electrolysis activity of CoPc centres. Here we show that the assembled CO2 electrolyzer using CoPc/ppy/GDE electrode achieves stable operation for 120 h at 500 mA cm−2 and 50 h at 1 A cm−2 in alkaline media. When coupled with a triple-junction solar cell, the resulting photovoltaic-electrolysis system attains a solar-to-CO efficiency of 19.2%.

The development of carbon dioxide reduction catalysts at industrial current densities remains challenging. Here, the authors demonstrate that in situ electro-polymerization of cobalt phthalocyanine on a gas diffusion electrode achieves high carbon monoxide selectivity at high current densities.