Catalytic Janus nanosheets were synthesized by using an anion-exchange reaction between heteropolyacids (HPAs) and the modified ionic-liquid (IL) moieties of Janus nanosheets. Their morphology and surface properties were characterized by using SEM, energy-dispersive spectroscopy (EDS), FTIR spectroscopy, and X-ray photoelectron spectroscopy (XPS) studies. Because of their inherent Janus structure, the nanosheets exhibited good amphipathic character with ILs and oil to form a stable ILs-in-oil emulsion. Therefore, these Janus nanosheets can be used as both emulsifiers and catalysts to perform emulsive desulfurization. During this process, sulfur-containing compounds at the interface could be easily oxidized and efficiently removed from a model oil. Application of this Janus emulsion brings an efficient, useful, and green procedure to the desulfurization process. Compared with the desulfurization catalyzed by using HPAs in a conventional two-phase system, the sulfur removal of dibenzothiophene (DBT) achieved in a Janus emulsion system was improved from 68 to 97 % within 1.5 h. Moreover, this emulsion system could be demulsified easily by simple centrifugation to recover both the nanosheets and the ILs. Owing to the good structural stability of the Janus nanosheets, the sulfur removal efficiency of DBT could still reach 99.9 % after the catalytic nanosheets had been recycled at least six times.

In this review, we evaluate and summarize the application of expanded graphite-based materials in rechargeable batteries, including alkaline ions (such as Na+, K+) storage and multivalent ion (such as Mg2+, Zn2+, Ca2+ and Al3+) storage batteries.

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An integrated composite of meso-cellular silicate foam (MCF)-modified reduced graphene oxide (MCF@rGO) was designed and synthesized based on polyethylene oxide–polypropylene oxide–polyethylene oxide (P123)-modified rGO (P123-rGO). As the polymeric template for the fabrication of mesoporous silicates, modified P123 greatly improved the affinity between the nanosheet and the in situ formed MCFs, resulting in the formation of thin layers of MCFs on both sides of rGO. Therefore, the MCFs@rGO formed exhibited a unique sandwich structure with an inner skeleton of rGO and two outer layers of MCFs. The outer modification by MCFs, with the presence of large mesopores, not only shifted the surface property of rGO from hydrophobic to hydrophilic but also offered immobilized enzymes a favorable microenvironment to maintain their bioactivity. Meanwhile, the inner skeleton of rGO compensated for the weak conductivity of MCFs, providing a pathway for the direct electron transfer (DET) of various redox enzymes or proteins, such as hemoglobin (Hb), horseradish peroxidase, glucose oxidase (GOD), and cholesterol oxidase. It was found that the DET signal obtained from Hb-MCFs@rGO/glassy carbon electrode (GCE) was much larger than the sum of the signals from two components-based modified electrodes of Hb-P123-rGO/GCE and Hb-MCFs/GCE. A similar improvement in DET signal was also observed using GOD-MCFs@rGO/GCE. The significant enhancement of DET signals for both protein electrodes can be ascribed to the synergistic effects generated from the integration of the two components, one of which enhances biocompatibility and the other enhances conductivity. The bioelectrocatalytic performance of Hb and GOD electrodes was further investigated. As for Hb-MCFs@rGO/GCE, the GOD electrode displayed excellent analytical performance for the detection of hydrogen peroxide (H2O2), including a good sensitivity of 0.25 μA μmol–1 L cm–2, a low detection limit of 63.6 nmol L–1 based on S/N = 3, and a low apparent Michaelis–Menten constant (K M app) of 49.05 μmol L–1. GOD-MCFs@rGO/GCE also exhibited good analytical performance for the detection of glucose, with a wide linear range of 0.25–8.0 mmol L–1. In addition, blood glucose detection in samples of human serum was successfully achieved using GOD-MCFs@rGO/GCE with a low quantification limit.

Poly(N‐isopropylacrylamide)‐modified graphene oxide (PNIPAm‐GO), which is a type of thermally responsive GO, was designed and synthesized through a covalent “grafting‐from” strategy. The as‐prepared modified nanosheets integrated the individual advantages of two components, such as the thermal sensitivity of the PNIPAm terminal as well as the conductivity and the open 2D structure of the GO substrate. PNIPAm‐GO was able to perform the reversible regulation of hydrophilicity/hydrophobicity in aqueous solution upon variations in the temperature. Such a unique property might also lead to the utilization of PNIPAm‐GO as an intelligent electrode material to achieve a switchable electrochemical response toward a [Fe(CN)6]3−/4− probe. The PNIPAm‐GO modified glassy carbon electrode (PNIPAm‐GO/GC electrode) was able to exhibit better electrochemical performance in an ON/OFF switching effect than the PNIPAm‐modified glassy carbon electrode (PNIPAm/GC electrode) without GO owing to the intrinsic properties and large surface area of the introduced GO. Moreover, it was found that the PNIPAm‐GO/GC electrode also displayed excellent thermally responsive electrocatalysis toward the detection of 1,4‐dihydro‐β‐nicotinamide adenine dinucleotide (NADH) and dopamine (DA), which resulted in two different catalytic statuses on the same electrode. This kind of switchable catalytic performance of the PNIPAm‐GO/GC electrode might greatly enhance the flexibility of its application, and thus it is expected to have wide potential for applications in the fields of biosensors and biocatalysis.