Endowing graphene with superior cation/anion co-purification and visible photocatalysis performances by in situ deposition of silver compounds

Abstract

Conventional adsorbents were usually subject to problems such as low adsorption capacity, poor single performance, and difficulty in recovery and processing when they confronted the anfractuous highly toxic wastewater containing abundant cations and anions. To overcome these problems, a fascinating regular honeycomb-like structure of a Ag₂O/reduced graphene oxide (Ag₂O/rGO) aerogel was skillfully fabricated via self-assembly/reduction of graphene oxide and in situ deposition of Ag₂O nanoparticles. Herein, the introduced Ag₂O provided rGO with the ability to selectively adsorb anions; due to this ability of rGO, the resultant Ag₂O/rGO aerogels possessed the potential to safely and efficiently co-purify toxic anions/cations. To our delight, the resulting Ag₂O/rGO aerogels not only exhibited a fast co-removal kinetic rate and superior co-capture performance towards several kinds of cationic/anionic pairs (Sr²⁺ ≈ 1.75 and Br⁻ ≈ 4.32 mmol g⁻¹, Cs⁺ ≈ 0.86 and I⁻ ≈ 5.24 mmol g⁻¹, etc.), but also showed an additional excellent visible light photocatalytic activity towards MB (90% of 15 mg ml⁻¹ MB was degraded within 60 min). Furthermore, the Ag₂O/rGO aerogels with moldable shapes solved the problem of easy loss and difficult post-processing of adsorbents. Additionally, the as-fabricated Ag₂O/rGO compounds possess an outstanding adsorption capacity to other cations or anions, such as Pb²⁺, Cu²⁺, Rb²⁺, Cr³⁺, S²⁻, SO₄²⁻, SO₃²⁻, and PO₄³⁻. Therefore, the Ag₂O/rGO aerogels could serve as efficient and practical adsorbents for hyper-complex water remediation.