# Synergistic Carbon Encapsulation and Silver Decoration Enable Durable and Selective CO2-to-Ethylene Conversion on Copper Oxide Photoelectrode

## TL;DR

Researchers developed a durable and selective photoelectrode that efficiently converts CO2 into ethylene using a combination of carbon encapsulation and silver decoration.

## Contribution

A synergistic strategy combining carbon encapsulation and metal decoration is introduced to enhance durability and selectivity in CO2-to-ethylene conversion.

## Key findings

- An ultrathin carbon layer encapsulation strategy significantly improves the durability of CuOx photocathodes.
- Ag nanoparticles enhance CO2 adsorption and ethylene selectivity, achieving ~66.4% Faraday efficiency.
- The strategy is broadly applicable, demonstrated with CuOx@C/Ru, CuOx@C/Pd, and BiVO4@C/Pt.

## Abstract

Chemical alterations in metal oxides during manipulation greatly diminish their potential in artificial photosynthesis. Clarifying and overcoming these changes is crucial for realizing the sustainable generation of solar fuels and chemicals. Here, employing multimodal operando techniques, we elucidated the degradation mechanism of copper oxide (CuOx) photocathodes under operational conditions, revealing an electron-mediated reductive photocorrosion pathway: Cu2O/CuO → Cu2O → Cu. These key findings led us to engineer an ultrathin carbon layer encapsulation strategy formed via electrodeposition-coupled self-assembly of carbon nanodots. This protective layer enables efficient photoelectron extraction and spatial isolation. The resulting CuOx@C exhibits gratifying durability with unaltered phases and steady photocurrent throughout extended operation exceeding 24 h. To enhance activity and selectivity toward ethylene, Ag nanoparticles were integrated onto CuOx@C. The Ag decoration enhances CO2 adsorption, stabilizes *CO intermediate, and facilitates the crucial *CO–*CO coupling. The Faraday efficiency for CO2-to-ethylene conversion on CuOx@C/Ag reaches up to ~66.4% and retains ~95% of its initial performance after prolonged use. This synergistic strategy of carbon encapsulation and metal decoration exhibits broad applicability, as validated by CuOx@C/Ru, CuOx@C/Pd, and BiVO4@C/Pt. Our work provides a universal design framework for efficient and durable photoelectrodes, accelerating their transition from laboratory prototypes to scalable technologies.