Highly Dispersed Ag Nanocrystals Anchored on N‐Doped Holey Carbon Aerogel as High‐Mass‐Loading Electrode for Cl⁻ Capture in Hybrid Capacitive Deionization

Abstract Nanostructured Faradaic materials show extraordinary promise for capacitive deionization (CDI) toward the relief of global freshwater scarcity. But at present, there exist at least two shortages for the development of CDI electrode materials. In laboratory studies, evaluating their desalination performance is usually based on low mass loadings (<1 mg cm⁻²), which is far behind the practical demand for fabricating high‐mass‐loading CDI electrodes or devices. On the other hand, high efficient, high active anode materials are rather scarce. Herein, highly dispersed Ag nanocrystals are synthesized on N‐doped holey carbon (Ag@NHC) for use as a high‐performance Cl⁻‐capture electrode at practical levels of mass loading. The Ag@NHC material is characteristic of ultrafine Ag nanocrystals with size of ≈7 nm anchored on carbon through Ag─N bonds, abundant 1–20 nm in‐plane pores in carbon sheets, and an ultrahigh specific surface area (1827.9 m² g⁻¹). This ensures Ag@NHC electrode (at 6.4 mg cm⁻² mass loading) with excellent structural and property stabilities, >80% atom‐economic utilization of Ag, as well as superior Cl⁻‐capture performances. This work provides a general guideline on how to estimate the optimal mass loadings for constructing highly active CDI electrodes in the future.