Size‐Dependent Effect of Ni Nanoparticles Confined in Ni‐Modified Flower‐Like Carbon Toward CO2 Electroreduction Reaction

Why It Matters

The findings provide a clear route to durable, high‑selectivity CO2 electroreduction catalysts, a critical step toward commercial renewable fuel production.

Key Takeaways

• Flower-like carbon confines Ni, stabilizing moderate nanoparticles.
• CO faradaic efficiency reaches ~90% at -1.0 V vs RHE.
• Catalyst retains >85% FECO after 30 hours continuous operation.
• Particle growth exposes Ni, increasing hydrogen evolution reaction.
• Confinement engineering offers strategy for durable CO2RR catalysts.

Pulse Analysis

Electrochemical conversion of carbon dioxide into value‑added fuels hinges on catalysts that combine high selectivity with long‑term stability. Nickel‑nitrogen doped carbons have emerged as promising candidates, yet the inevitable formation of metallic Ni nanoparticles during synthesis has traditionally been viewed as detrimental, promoting the competing hydrogen evolution reaction. By embedding Ni within a hierarchically porous, flower‑like carbon matrix, researchers created a dual‑site architecture where atomically dispersed Ni‑N‑C sites coexist with size‑tuned nanoparticles, mitigating the adverse effects while leveraging the intrinsic activity of metallic Ni.

Performance testing showed that modest Ni loadings (0.2–1 mmol) produce uniformly small nanoparticles that enhance microporosity and deliver a CO faradaic efficiency of approximately 90% at –1.0 V versus RHE. Remarkably, the catalyst sustained over 85% efficiency for a continuous 30‑hour run, a benchmark rarely achieved in laboratory CO2RR studies. Advanced in‑situ electron microscopy and density functional theory calculations traced the deactivation pathway to gradual particle coarsening; as nanoparticles emerge from confinement, they become exposed, catalyzing hydrogen evolution and raising the activation barrier for the *COOH intermediate essential to CO formation.

The broader implication is that nanoscale confinement can be systematically exploited to balance the benefits of metallic sites against their propensity for HER promotion. This design principle opens avenues for scaling durable CO2 electroreduction systems, informing future catalyst development that targets both activity and longevity. As the renewable energy sector seeks economically viable carbon‑neutral fuels, such confinement‑engineered catalysts could accelerate the transition from bench‑scale prototypes to commercial electrolyzers.